文件类型：PDF/Adobe Acrobat 文件大小：字节
________________________________概述
MAX4836/MAX4837是低压差(LDO)线性稳压器,具有
精确的限流开关,以及集成的FLAG或RESET功能.这
些器件工作于2.5V至5.5V电源,在预置输出电压下可以
提供高达500mA的负载电流.预置输出电压为1.8V/2.5V/
2.8V/3.0V/3.3V.
MAX4836/MAX4837提供可编程的软启动控制功能,可
以消除启动过程中的错误复位.MAX4836在负载电流超
过限制时向系统发出FLAG信号.MAX4837在输出电压
下降到低于门限值时向系统发出RESET信号.另外,反
向电流保护电路可以防止电流从输出流进输入.其它特
性还包括90 A低静态电流和0.1 A关断电流.
MAX4836/MAX4837提供节省空间的6引脚SOT23与
TDFN封装.每款器件都工作在-40°C至+85°C扩展级温
度范围.如需1.5V至3.3V范围内,增量为100mV的其它
可编程输出电压,请与厂商联系.
如需与该器件引脚兼容的100mA产品,请参考MAX4832/
MAX4833.与该器件引脚兼容的250mA产品,请参考
MAX4834/MAX4835.
________________________________应用
SDIO 端口与设备笔记本电脑
USB 端口与设备蜂窝电话
PDA 与掌上电脑设备GPS系统
________________________________特性
确保最小500mA负载电流
精确的电流限制
预置输出电压:1.8V/2.5V/2.8V/3.0V/3.3V
2.5V至5.5V电源电压范围
可调节软启动
低压差
热关断
反向电流保护
关断输出放电电路(MAX4837)
90 A的低电源电流
0.1 A的超低关断电流
FLAG和闭锁(MAX4836)或RESET(MAX4837)
细小的SOT23与TDFN (3mm x 3mm)封装
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
____________________________定购信息
19-3374; Rev 0; 7/04
注:尾标"xy"表示器件的输出电压,本文最后部分的表1给出了
"xy"的具体数值.尾标"_"表示带有RESET功能或FLAG功能.
在"_"位置填入"B"表示RESET功能,填入"C"表示FLAG功
能.尾标"dd"表示复位超时周期.表2列出了"dd"的数值.例
如,MAX4837EUT18BD2的输出电压为1.8V,具有RESET功能,
复位超时周期为30ms.注意:"dd"仅用于具有RESET功能的器
件,对于带有FLAG功能的器件没有意义.对于带有FLAG功能
的器件,dd项空缺.标准版本的器件需要最少2.5k的定货量.非
标准版本的单位定货量为10k.供货情况请与厂商联系.
*未来产品--供货情况请联系厂商.
PART TEMP RANGE PIN-PACKAGE
MAX4836EUTxy_-T* -40°C to +85°C 6 SOT23-6
MAX4836ETTxy_-T -40°C to +85°C 6 TDFN-6
MAX4837EUTxy_dd-T* -40°C to +85°C 6 SOT23-6
MAX4837ETTxy_dd-T -40°C to +85°C 6 TDFN-6
6OUT
5SS
4RESET
(FLAG)
1
2GND
3SHDN
MAX4836/MAX4837
IN
TDFN
EXPOSED PADDLE
TOP VIEW
( ) MAX4836ETTxyC ONLY.
____________________________引脚配置
引脚配置(续)见数据资料的最后部分.
表1,表2以及选择指南在数据资料的最后部分给出.
________________________________________________________________Maxim Integrated Products1
本文是Maxim正式英文资料的译文,Maxim不对翻译中存在的差异或由此产生的错误负责.请注意译文中可能存在文字组织或
翻译错误,如需确认任何词语的准确性,请参考Maxim提供的英文版资料.
索取免费样品和最新版的数据资料,请访问Maxim的主页:www.maxim-ic.com.cn.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, SHDN, FLAG, OUT to GND ................................-0.3V to +6V
RESETto GND .........................................-0.3V to (VOUT+ 0.3V)
SS to GND ...................................................-0.3V to (VIN+ 0.3V)
IN to OUT ...............................................................................±6V
OUT Short Circuit to GND ..........................................Continuous
All Pins ESD Handling (Human Body Model).........................2kV
Continuous Power Dissipation (TA= +70°C)
6-Pin SOT23 (derate 9.1mW/°C above +70°C)................727mW
6-Pin TDFN (derate 24.4mW/°C above +70°C) ..........1951.2mW
Operating Temperature Range ...........................-40°C to +85°C
Operating Junction Temperature Range ...........-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Voltage VIN2.5 5.5 V
Input Undervoltage Lockout
Threshold
VUVLOVIN rising 2.00 2.25 V
Input Undervoltage Lockout
Threshold Hysteresis
50 mV
SHDN = IN, IOUT = 0 90 150
SHDN = IN, IOUT = 0,
VUVLO < VIN < VOUT (nominal)
150Quiescent Current IQ
SHDN = GND, IOUT = 0 0.1 2
A
TA = +25°C 200 300
Dropout Voltage (Note 2) IOUT = 500mA
TA = -40°C to +85°C 330
mV
IOUT = 1mA to 500mA, TA = +25°C -1.3 +1.3
Output Voltage Accuracy
IOUT = 1mA to 500mA, TA = -40°C to +85°C -2 +2
%VNOM
Output Current IOUT500 mA
Output Current Limit VOUT = 0V 540 660 mA
Reverse Current at VINVOUT = 5.5V, VIN = 0V to VOUT0.1 2 A
CSS = not connected 0.5 1 2.0
CSS = 0.01 F 4 10 15Soft-Start Time (Note 3) tSS
CSS = 0.1 F 40 100 150
ms
TA = +25°C -0.04 +0.02 +0.065
Line Regulation (Note 4)
VOUT + 0.5V < VIN <
5.5V, ILOAD = 100 ATA = -40°C to +85°C -0.05 +0.03 +0.08
%VNOM/
V
Load Regulation 100 A < ILOAD < 500mA, VIN = VOUT + 1V 1.3 %VNOM
Output Noise 10Hz to 100kHz, CSS = 0.01 F 70 VRMS
SHUTDOWN INPUT (SHDN)
OUT Discharge Resistance in
Shutdown (MAX4837)
SHDN = GND 900
SHDN Input-Voltage High VIH1.4 V
SHDN Input-Voltage Low VIL0.5 V
SHDN Input Hysteresis30 mV
SHDN Input Leakage CurrentSHDN = IN or GND -100 +100 nA
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
_______________________________________________________________________________________ 3
Note 1:Parts are 100% tested at +25°C. Limits across the full temperature range are guaranteed by design and correlation over the
specified temperature range.
Note 2:The dropout voltage is measured from VINto VOUTwhen VOUTis 2% below its nominal value. The nominal output voltage is
measured from VOUTto GND when VINis 1V greater than VOUT. Defined only for VOUT≥2.5V.
Note 3:Soft-start time is defined as the time required for the output to rise from 10% of its nominal value to 90% of its nominal value.
Note 4:For VOUT< 2V, VINmust be above 2.5V.
Note 5:This is the maximum time OUT can be out of tolerance before a reset is issued. It is implemented to ensure that momentary
output glitches do not trigger a reset condition.
Note 6:In startup mode, the blanking time counter is not started until the soft-start time has elapsed. The total time from startup to
FLAGissued is tSS+ tBLANK.
ELECTRICAL CHARACTERISTICS (continued)
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RESET OUTPUT (MAX4837)
RESET Threshold VRESET
0.85 x
VOUT
0.875 x
VOUT
0.90 x
VOUT
V
OUT Drop to RESET Delay
(Note 5)
tOR35 s
D1 timing option 2.5 3.75 5.0
D2 timing option 20 30 40
D3 timing option 150 225 300
RESET Timeout Period tRESET
D4 timing option 1200 1800 2400
ms
VOUT ≥ 1.0V, ISINK = 50 A, RESET asserted 0.3
RESET Output-Voltage LowVOUT ≥ 1.5V, ISINK = 3.2mA, RESET
asserted
0.4
V
RESET Output-Voltage High
VOUT ≥ 2.0V, ISOURCE ≤ 500 A,
RESET deasserted
0.8 x
VOUT
V
FLAG OUTPUT (MAX4836)
Blanking Time (Note 6) tBLANKVOUT + 1V ≤ VIN ≤ 5.5V, OUT = GND 5 10 17 ms
Open-Drain FLAG Output-
Voltage Low
ISINK = 3.2mA, FLAG asserted, VOUT ≥ 1.5V 0.4 V
Open-Drain FLAG Leakage
Current
VFLAG = 5.5V 0.01 1 A
THERMAL PROTECTION
Thermal-Shutdown Temperature Junction temperature rising +165 °C
Thermal-Shutdown Hysteresis15 °C
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
4 _______________________________________________________________________________________
_______________________________________________________________典型工作特性
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= +25°C, unless otherwise noted.)
QUIESCENT CURRENT vs. INPUT VOLTAGE
(NO LOAD)
MAX4836 toc01
VIN (V)
IQ ( A)
54321
20
40
60
80
100
120
0
06
TA = +85°C
TA = -40°C
TA = +25°C
VOUT = 1.5V
QUIESCENT CURRENT vs. INPUT VOLTAGE
(500mA LOAD)
MAX4836 toc02
VIN (V)
IQ ( A)
5432106
TA = +85°C
VOUT = 3.3V
TA = -40°C
100
200
300
400
500
600
700
800
0
TA = +25°C
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX4836 toc03
RESET THRESHOLD OVERDRIVE (mV)
PULSE DURATION ( s)
10
15
30
45
60
75
90
0
1100
RESET ASSERTS
ABOVE THIS LINE
VIN = 3.5V
VOUT = 2.5V
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX4836 toc04
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
400300200100
30
60
90
120
150
180
0
0500
VOUT = 3.3V
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4836 toc05
FREQUENCY (kHz)
PSRR (dB)
1010.1
-70
-60
-50
-40
-30
-20
-10
0
-80
0.01 100
VOUT = 2V
COUT = 3.3 F
ILOAD = 20mA
REGION OF STABLE COUT ESR
vs. LOAD CURRENT
MAX4836 toc06
LOAD CURRENT (mA)
COUT ESR ( )
1
2
3
4
5
6
7
0
VOUT = 1.8V
COUT = 3.3 F
STABLE REGION
450400350300250200150100500500
OUTPUT NOISE vs. FREQUENCY
MAX4836 toc07
FREQUENCY (Hz)
OUTPUT NOISE ( VRMS)
10k1k100
10
20
30
40
50
0
10 100k
VIN = 3V
VOUT = 1.8V
CSS = 10nF
ILOAD = 0
SOFT-START RESPONSE
(CSS = FLOATING)
MAX4836 toc08
VSS
1V/div
VOUT
2V/div
VIN
2V/div
2ms/div
tSS
_______________________________________________________________________________________ 5
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
SOFT-START RESPONSE
(CSS = 0.01 F)
MAX4836 toc09
VSS
1V/div
VOUT
2V/div
VIN
2V/div
2ms/div
tSS
SOFT-START RESPONSE
(CSS = 0.1 F)
MAX4836 toc10
VIN
2V/div
VSS
1V/div
VOUT
2V/div
20ms/div
tSS
LOAD-TRANSIENT RESPONSE
MAX4836 toc11
VOUT
50mV/div
AC-COUPLED
100 s/div
VIN = 4.3V
VOUT = 3.3V
CIN = 0.1 F
COUT = 3.3 F
ILOAD: STEP FROM 10mA TO 100mA
BACK TO 10mA
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
MAX4836 toc12
VOUT
50mV/div
AC-COUPLED
100 s/div
VIN = 3.4V
VOUT = 3.3V
CIN = 0.1 F
COUT = 3.3 F
ILOAD: STEP FROM 10mA TO 100mA
BACK TO 10mA
LINE-TRANSIENT RESPONSE
MAX4836 toc13
VOUT
50mV/div
AC-COUPLED
100 s/div
CIN = 0.1 F
COUT = 3.3 F
VOUT = 3.3V
ILOAD = 10mA
5V
VIN
500mV/div
4.5V
RESET RESPONSE TO VIN
MAX4836 toc14
VRESET
2V/div
VOUT
2V/div
VIN
2V/div
40ms/div
tRESET
CSS = FLOATING
RESET RESPONSE TO VOUT
MAX4836 toc15
VRESET
1V/div
VOUT
1V/div
40ms/div
tRESET
VIN = 3.5V, CSS = FLOATING
RESET RESPONSE TO SHUTDOWN
MAX4836 toc16
VRESET
2V/div
VOUT
2V/div
VSHDN
2V/div
40ms/div
tRESET
VIN = 3.5V, CSS = FLOATING
____________________________________________________________典型工作特性(续)
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= +25°C, unless otherwise noted.)
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
6 _______________________________________________________________________________________
____________________________________________________________典型工作特性(续)
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= +25°C, unless otherwise noted.)
FLAG RESPONSE WHEN OUT IS
SHORTED TO GND BLANKING TIME
(IN IS TOGGLED)
MAX4836 toc18
VOUT
1V/div
10ms/div
VIN
2V/div
VFLAG
2V/div
FLAG CONNECTED TO LOGIC SUPPLY
tBLANK
STARTUP IN AN OVERLOAD CONDITION
(CSS NOT CONNECTED)
MAX4836 toc20
VSS
1V/div
VFLAG
2V/div
VOUT
2V/div
2ms/div
tBLANK
VIN
2V/div
tSS
VOUT = 2.5V
ILOAD = ILIMIT MAXIMUM
FLAG CONNECTED TO LOGIC SUPPLY
STARTUP IN AN OVERLOAD CONDITION
(CSS = 0.01 F)
MAX4836 toc21
VSS
1V/div
VFLAG
2V/div
VOUT
2V/div
4ms/div
tBLANK
VIN
2V/div
tSS
VOUT = 2.5V
ILOAD = ILIMIT MAXIMUM
FLAG CONNECTED TO LOGIC SUPPLY
NORMALIZED OUTPUT VOLTAGE
vs. TEMPERATURE
MAX4836 toc22
TEMPERATURE (°C)
NORMALIZED OUTPUT VOLTAGE
603510-15
0.996
0.998
1.000
1.002
1.004
0.994
-40 85
NORMALIZED TO +25°C
ILOAD = 500mA
ILOAD = 300mA
ILOAD = 100mA
FLAG RESPONSE WHEN OUT IS
SHORTED TO GND > BLANKING TIME
(SHDN IS TOGGLED)
MAX4836 toc19
VOUT
1V/div
10ms/div
VSHDN
2V/div
VFLAG
2V/div
FLAG CONNECTED TO LOGIC SUPPLY
tBLANK
____________________________详细说明
MAX4836/MAX4837低压差线性稳压器具有超低静态电
流,并带有集成限流器.这些器件能保证高达500mA的
驱动能力,并稳定在预置输出电压.
MAX4836有一个标志输出,当负载电流超过电流限且
持续时间超过屏蔽时间(tBLANK)时,该输出变低.
MAX4837有一个复位输出,当稳压器输出电压低于复位
门限电压(VRESET)时,该输出变低.VRESET为标称输出
电压的87.5%.图1给出了简化的功能框图,图2给出了
典型应用电路.
FLAG输出(MAX4836)
当调整管流过的电流达到它的输出电流限且持续时间超
过屏蔽时间(tBLANK)时,漏极开路输出FLAG变低,同时
LDO的调整管闭锁.重新上电或刷新SHDN控制(由高到
低,再到高)会使器件退出闭锁状态,并返回到正常工作
状态.
RESET输出(MAX4837)
当出现以下条件之一时,将触发RESET复位输出:
输入电压(VIN)低于输入欠压锁定门限(VUVLO).
输出电压(VOUT)低于复位门限(VRESET).
拉低SHDN.
器件处于热关断状态.
当VOUT> VIN时.
复位条件结束后,RESET在复位超时周期(tRESET)内仍保
持低电平.提供四种RESET超时周期,如Electrical
Characteristics表所示.RESET采用推挽输出结构,见选
择指南.
关断
将SHDN拉低可关断LDO,并将器件的静态电流从90 A
降低到0.1 A.在关断模式下,调整管,控制电路和基准
电路都关闭.将SHDN接到大于VIH的电源电压上可开启
LDO.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
_______________________________________________________________________________________ 7
___________________________________________________________________引脚说明
PIN
SOT23 TDFN
NAME FUNCTION
11 IN
Regulator Power Input. Bypass IN to GND with a 0.1 F ceramic capacitor. Install the bypass
capacitor as close to the device as possible.
2 2 GND Ground
33SHDN
Active-Low Shutdown Input. Drive SHDN low to shutdown the regulator. Drive SHDN high or
connect to IN for normal operation.
FLAG
(MAX4836)
Overcurrent Flag. Open-drain FLAG goes low when the device senses sustained current
exceeding the current-limit threshold for a duration longer than the blanking time. FLAG is high
when SHDN is low or the device is in thermal shutdown.
44
RESET
(MAX4837)
Active-Low Reset Output. Push-pull RESET goes low when the voltage at OUT is below the reset
threshold or when the voltage at OUT is greater than IN. RESET is low when SHDN is low or the
device is in thermal shutdown. After the reset condition terminates, RESET remains low for the
duration of the reset timeout period.
55 SS
Soft-Start Control. Connect a capacitor, CSS, from SS to GND to program the output rise time at
startup. No capacitor from SS to GND gives 1ms output rise time at startup. See the soft-start
response time plots in the Typical Operating Characteristics.
6 6 OUT
Regulator Output. Bypass OUT to GND with a 3.3 F or larger ceramic capacitor. The capacitor's
ESR should be less than 0.2 for stable operation.
—EP EP
Exposed Pad. EP is internally connected to GND. Externally connect EP to GND to provide a low
thermal resistance path from the IC junction to the PC board.
引脚
名称功能
稳压器电源输入.用一个0.1 F陶瓷电容将IN旁路至GND.旁路电容应安装在尽可能靠近器件的
位置.
地
低电平有效关断输入.将SHDN置低可关断稳压器.SHDN接高电平或接至IN可正常工作.
过流标志.当器件检测到电流超过电流门限值,且持续时间超过屏蔽时间时,漏极开路FLAG输出
变低.当SHDN为低或器件处于热关断状态时,FLAG为高.
低电平有效复位输出.当OUT上的电压低于复位门限值或者高于IN引脚上的电压时,推挽输出
RESET变低.当SHDN为低或器件处于热关断状态时,RESET为低电平.复位条件结束后,
在复位超时周期内RESET仍保持低电平.
软启动控制.在SS和GND之间接一个电容CSS,来设置启动时的输出上升时间.SS和GND之间
不接电容时,会在启动时产生1ms的输出上升时间.见典型工作特性中的软启动响应时间图
(soft-start response).
稳压器输出.用一个3.3 F或更大的陶瓷电容将OUT旁路至GND.为了实现稳定工作,电容的ESR
应小于0.2 .
裸露焊盘.EP在内部与GND相连.从外部将EP接至GND,可为IC到PC板之间提供低热阻通路.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
8 _______________________________________________________________________________________
REVERSE-
CURRENT
PROTECTION
PASS
TRANSISTOR
RESET TIMEOUT
(BLANKING PERIOD)
OVERLOAD
PROTECTION
VSS
vFB
VREF
VFB
VREF
ERROR
AMPLIFIER
1.23V
90% x VREF
VREF
VSS = VREF
WHEN SOFT-START
IS COMPLETE
SWITCH OPEN
DURING SOFT-START
VSS
1.23 A
1nF
SWITCH
CLOSED IN
SHUTDOWN
MAX4837 ONLY
THERMAL
PROTECTIONMAX4836/MAX4837
IN
SHDN
RESET
(FLAG)
GND
SS
OUT
900
( ) MAX4836E_ _xyC ONLY.
图1. 功能框图
MAX4836
LOAD
COUT
3.3 F
CSS
ON
OFF
OUT
SS
SHDN
FLAG
IN
GND
MAX4837
LOAD
COUT
3.3 F
CIN
0.1 F
2.5V TO 5.5V
CSS
TO C
ON
OFF
OUT
SS
SHDN
RESET
IN
GND
CIN
0.1 F
2.5V TO 5.5V
TO C
VLOGIC
图2. 典型应用电路
关断放电电路(MAX4837)
在关断模式下,OUT通过900 的内部电阻进行放电.
OUT到IN反向电流
当输出电压大于输入电压时,内部调整管关闭.当VOUT≥
VIN时,为避免对输入电源反向充电,IN电流确保低于
3 A.
电流限制
MAX4836/MAX4837包含一套精确的内部限流电路.即
使OUT与地短接也不会损坏器件.
如果负载电流超过电流限且持续时间超过屏蔽时间(见
FLAG输出部分),MAX4836会发生闭锁.在软启动过程
中,过载条件不会引起器件闭锁.过载条件下,在温度
达到热限制之前,MAX4837将电流保持为限流值;一旦
结温达到+165°C,就会发生热关断.
热关断
当结温(TJ)超过+165°C时,LDO的调整管会关断从而降
低结温.当IC的结温降低了15°C后,LDO的调整管重新
打开,即在持续热过载条件下会产生脉冲输出.
软启动
在上电过程中,软启动确保输出缓慢上升,从而减小了
浪涌峰值电流.请参考典型工作特性中的软启动响应
(soft-start response)时间图.软启动时间(tSS)由下式给
出:
tSS= CSS(ms)
式中CSS的单位为nF.
10nF的软启动电容(CSS)会产生10ms的软启动时间tSS.
内部设置了一个1ms的最小软启动时间,这样即使在SS
引脚和地之间不加任何外部电容的情况下,也能确保输
出缓慢上升.重新上电或者刷新SHDN控制时,器件会
进入软启动模式.
____________________________应用信息
电容选择以及稳压器稳定性
为了能在整个温度范围和负载电流高达500mA的情况下
稳定工作,使用一个ESR <0.2 的3.3 F(最小)陶瓷输出
电容.为降低噪声并改善负载瞬态响应,稳定性和电源
抑制,可使用更大的输出电容,如10 F(需注意一些陶
瓷电容的电容值和ESR会随温度变化而发生较大变化).
X7R电容在整个-40°C到+85°C的工作温度范围内都具有
很好的性能.
为了提高电源抑制能力并改善瞬态响应,可在IN和GND
之间接一个0.1 F的电容.在纯阻性负载或负载电流高达
500mA的情况下,MAX4836/MAX4837都能保持稳定.
15kV ESD保护
在OUT和GND之间接一个3.3 F或更高容值的陶瓷电容
会在OUT端提供15kV(人体模型)ESD保护.电容的ESR
值应小于0.2 .
复位瞬态抑制
复位电路不受短时的VOUT跌落影响.典型工作特性给出
了不会触发复位输出的Maximum Transient Duration vs.
Reset Threshold Overdrive关系曲线图.该曲线图是通过
测试瞬间跌落的输出电压产生的,输出电压从VOUT开始
跌落,并终止在低于复位门限的某个电平上,图中给出
了该电平低于复位门限的幅度(复位门限过驱动).曲线
图给出了在不触发复位脉冲情况下,一个VOUT跌落可以
具有的最大典型脉宽.随着跌落幅度的增大(即比复位门
限低出更大的幅度),最大允许脉宽降低.典型情况下,
一个比复位门限值仅低10mV的VOUT跌落,若持续时间
不超过54 s,则不会触发复位脉冲.
布局
当使用TDFN封装时,将其裸露焊盘接至GND,从而为
IC到印刷电路板之间的热传递提供一个低热阻通路.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
_______________________________________________________________________________________ 9
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
10 ______________________________________________________________________________________
_____________________________________________________________________________________________选择指南
PART
PIN-
PACKAGE
OUTPUT
CURRENT (mA)
RESET OUTPUT
CONFIGURATION
RESET
(FLAG)
SHUTDOWN
DISCHARGE
LATCH OFF
MAX4836EUTxyC-T 6 SOT23-6 500 Open-DrainFLAGNo Yes
MAX4836ETTxyC-T 6 TDFN-6 500 Open-DrainFLAGNo Yes
MAX4837EUTxyBdd-T 6 SOT23-6 500 Push-PullRESETYes No
MAX4837ETTxyBdd-T 6 TDFN-6 500 Push-PullRESETYes No
器件型号中的后缀'xy'表示标称输出电压.1.8V,2.5V,2.8V,3.0V和3.3V是标准电压选型.若需1.5V至3.3V范围内的其它电压,
请与厂商联系.
表1. 标准输出电压与型号后缀对照指南
xy OUTPUT VOLTAGE (V)
18 1.8
25 2.5
28 2.8
30 3.0
33 3.3
可提供1.5V至3.3V范围内,增量为100mV的非标准输出电压,
供货情况请与厂商联系.
表2. RESET超时周期与型号后缀对照指南
ddRESET TIMEOUT (ms)
D1 3.75
D2 30
D3 225
D4 1800
TOP VIEW
GND
SHDN
1 6 OUT
5SS
IN
MAX4836/
MAX4837
SOT23
2
34RESET
(FLAG)
( ) MAX4836EUTxyC ONLY.
_________________________引脚配置(续)
____________________________芯片信息
TRANSISTOR COUNT: 1575
PROCESS: BiCMOS
TDFN Exposed Pad: Connected to GND
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
______________________________________________________________________________________ 11
6, 8, &10L, DFN THIN.EPS
LCLC
PIN 1
INDEX
AREA
D
E
L
e
L
A
e
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY
E2
DETAIL A
N
F
1
221-0137
PACKAGE OUTLINE, 6, 8, 10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
COMMON DIMENSIONS
SYMBOLMIN. MAX.
A 0.70 0.80
D 2.90 3.10
E 2.90 3.10
A1 0.00 0.05
L0.200.40
PKG. CODEND2E2eJEDEC SPECb[(N/2)-1] x e
PACKAGE VARIATIONS
0.25 MIN.k
A2 0.20 REF.
2.30±0.101.50±0.106T633-1 0.95 BSC MO229 / WEEA1.90 REF
F
2
221-0137
PACKAGE OUTLINE, 6, 8, 10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
0.40±0.05
1.95 REF0.30±0.050.65 BSC2.30±0.108T833-1
2.00 REF0.25±0.050.50 BSC2.30±0.1010T1033-1
2.40 REF0.20±0.03- - - - 0.40 BSC1.70±0.10 2.30±0.1014T1433-1
1.50±0.10
1.50±0.10
MO229 / WEEC
MO229 / WEED-3
0.40 BSC- - - - 0.20±0.03 2.40 REFT1433-2 14 2.30±0.101.70±0.10
___________________________________________________________________封装信息
(本数据资料提供的封装图可能不是最近的规格,如需最近的封装外型信息,请查询www.maxim-ic.com.cn/packages.)
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
6LSOT.EPS
F
1
121-0058
PACKAGE OUTLINE, SOT-23, 6L
_______________________________________________________________封装信息(续)
(本数据资料提供的封装图可能不是最近的规格,如需最近的封装外型信息,请查询www.maxim-ic.com.cn/packages.)
Maxim不对Maxim产品以外的任何电路使用负责,也不提供其专利许可.Maxim保留在任何时间,没有任何通报的前提下修改产品资料和规格的权利.
12__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
2004 Maxim Integrated Products Printed USA是Maxim Integrated Products, Inc. 的注册商标.
MAXIM北京办事处
北京8328信箱邮政编码100083
免费电话:800 810 0310
电话:010-6201 0598
传真:010-6201 0298
·上一篇：静态存储器字MAX4836/MAX4837是低压差(LDO)线性稳压器,具有
精确的限流开关,以及集成的FLAG或RESET功能.这
些器件工作于2.5V至5.5V电源,在预置输出电压下可以
提供高达500mA的负载电流.预置输出电压为1.8V/2.5V/
2.8V/3.0V/3.3V.
MAX4836/MAX4837提供可编程的软启动控制功能,可
以消除启动过程中的错误复位.MAX4836在负载电流超
过限制时向系统发出FLAG信号.MAX4837在输出电压
下降到低于门限值时向系统发出RESET信号.另外,反
向电流保护电路可以防止电流从输出流进输入.其它特
性还包括90 A低静态电流和0.1 A关断电流.
MAX4836/MAX4837提供节省空间的6引脚SOT23与
TDFN封装.每款器件都工作在-40°C至+85°C扩展级温
度范围.如需1.5V至3.3V范围内,增量为100mV的其它
可编程输出电压,请与厂商联系.
如需与该器件引脚兼容的100mA产品,请参考MAX4832/
MAX4833.与该器件引脚兼容的250mA产品,请参考
MAX4834/MAX4835.
________________________________应用
SDIO 端口与设备笔记本电脑
USB 端口与设备蜂窝电话
PDA 与掌上电脑设备GPS系统
________________________________特性
确保最小500mA负载电流
精确的电流限制
预置输出电压:1.8V/2.5V/2.8V/3.0V/3.3V
2.5V至5.5V电源电压范围
可调节软启动
低压差
热关断
反向电流保护
关断输出放电电路(MAX4837)
90 A的低电源电流
0.1 A的超低关断电流
FLAG和闭锁(MAX4836)或RESET(MAX4837)
细小的SOT23与TDFN (3mm x 3mm)封装
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
____________________________定购信息
19-3374; Rev 0; 7/04
注:尾标"xy"表示器件的输出电压,本文最后部分的表1给出了
"xy"的具体数值.尾标"_"表示带有RESET功能或FLAG功能.
在"_"位置填入"B"表示RESET功能,填入"C"表示FLAG功
能.尾标"dd"表示复位超时周期.表2列出了"dd"的数值.例
如,MAX4837EUT18BD2的输出电压为1.8V,具有RESET功能,
复位超时周期为30ms.注意:"dd"仅用于具有RESET功能的器
件,对于带有FLAG功能的器件没有意义.对于带有FLAG功能
的器件,dd项空缺.标准版本的器件需要最少2.5k的定货量.非
标准版本的单位定货量为10k.供货情况请与厂商联系.
*未来产品--供货情况请联系厂商.
PART TEMP RANGE PIN-PACKAGE
MAX4836EUTxy_-T* -40°C to +85°C 6 SOT23-6
MAX4836ETTxy_-T -40°C to +85°C 6 TDFN-6
MAX4837EUTxy_dd-T* -40°C to +85°C 6 SOT23-6
MAX4837ETTxy_dd-T -40°C to +85°C 6 TDFN-6
6OUT
5SS
4RESET
(FLAG)
1
2GND
3SHDN
MAX4836/MAX4837
IN
TDFN
EXPOSED PADDLE
TOP VIEW
( ) MAX4836ETTxyC ONLY.
____________________________引脚配置
引脚配置(续)见数据资料的最后部分.
表1,表2以及选择指南在数据资料的最后部分给出.
________________________________________________________________Maxim Integrated Products1
本文是Maxim正式英文资料的译文,Maxim不对翻译中存在的差异或由此产生的错误负责.请注意译文中可能存在文字组织或
翻译错误,如需确认任何词语的准确性,请参考Maxim提供的英文版资料.
索取免费样品和最新版的数据资料,请访问Maxim的主页:www.maxim-ic.com.cn.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, SHDN, FLAG, OUT to GND ................................-0.3V to +6V
RESETto GND .........................................-0.3V to (VOUT+ 0.3V)
SS to GND ...................................................-0.3V to (VIN+ 0.3V)
IN to OUT ...............................................................................±6V
OUT Short Circuit to GND ..........................................Continuous
All Pins ESD Handling (Human Body Model).........................2kV
Continuous Power Dissipation (TA= +70°C)
6-Pin SOT23 (derate 9.1mW/°C above +70°C)................727mW
6-Pin TDFN (derate 24.4mW/°C above +70°C) ..........1951.2mW
Operating Temperature Range ...........................-40°C to +85°C
Operating Junction Temperature Range ...........-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Voltage VIN2.5 5.5 V
Input Undervoltage Lockout
Threshold
VUVLOVIN rising 2.00 2.25 V
Input Undervoltage Lockout
Threshold Hysteresis
50 mV
SHDN = IN, IOUT = 0 90 150
SHDN = IN, IOUT = 0,
VUVLO < VIN < VOUT (nominal)
150Quiescent Current IQ
SHDN = GND, IOUT = 0 0.1 2
A
TA = +25°C 200 300
Dropout Voltage (Note 2) IOUT = 500mA
TA = -40°C to +85°C 330
mV
IOUT = 1mA to 500mA, TA = +25°C -1.3 +1.3
Output Voltage Accuracy
IOUT = 1mA to 500mA, TA = -40°C to +85°C -2 +2
%VNOM
Output Current IOUT500 mA
Output Current Limit VOUT = 0V 540 660 mA
Reverse Current at VINVOUT = 5.5V, VIN = 0V to VOUT0.1 2 A
CSS = not connected 0.5 1 2.0
CSS = 0.01 F 4 10 15Soft-Start Time (Note 3) tSS
CSS = 0.1 F 40 100 150
ms
TA = +25°C -0.04 +0.02 +0.065
Line Regulation (Note 4)
VOUT + 0.5V < VIN <
5.5V, ILOAD = 100 ATA = -40°C to +85°C -0.05 +0.03 +0.08
%VNOM/
V
Load Regulation 100 A < ILOAD < 500mA, VIN = VOUT + 1V 1.3 %VNOM
Output Noise 10Hz to 100kHz, CSS = 0.01 F 70 VRMS
SHUTDOWN INPUT (SHDN)
OUT Discharge Resistance in
Shutdown (MAX4837)
SHDN = GND 900
SHDN Input-Voltage High VIH1.4 V
SHDN Input-Voltage Low VIL0.5 V
SHDN Input Hysteresis30 mV
SHDN Input Leakage CurrentSHDN = IN or GND -100 +100 nA
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
_______________________________________________________________________________________ 3
Note 1:Parts are 100% tested at +25°C. Limits across the full temperature range are guaranteed by design and correlation over the
specified temperature range.
Note 2:The dropout voltage is measured from VINto VOUTwhen VOUTis 2% below its nominal value. The nominal output voltage is
measured from VOUTto GND when VINis 1V greater than VOUT. Defined only for VOUT≥2.5V.
Note 3:Soft-start time is defined as the time required for the output to rise from 10% of its nominal value to 90% of its nominal value.
Note 4:For VOUT< 2V, VINmust be above 2.5V.
Note 5:This is the maximum time OUT can be out of tolerance before a reset is issued. It is implemented to ensure that momentary
output glitches do not trigger a reset condition.
Note 6:In startup mode, the blanking time counter is not started until the soft-start time has elapsed. The total time from startup to
FLAGissued is tSS+ tBLANK.
ELECTRICAL CHARACTERISTICS (continued)
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RESET OUTPUT (MAX4837)
RESET Threshold VRESET
0.85 x
VOUT
0.875 x
VOUT
0.90 x
VOUT
V
OUT Drop to RESET Delay
(Note 5)
tOR35 s
D1 timing option 2.5 3.75 5.0
D2 timing option 20 30 40
D3 timing option 150 225 300
RESET Timeout Period tRESET
D4 timing option 1200 1800 2400
ms
VOUT ≥ 1.0V, ISINK = 50 A, RESET asserted 0.3
RESET Output-Voltage LowVOUT ≥ 1.5V, ISINK = 3.2mA, RESET
asserted
0.4
V
RESET Output-Voltage High
VOUT ≥ 2.0V, ISOURCE ≤ 500 A,
RESET deasserted
0.8 x
VOUT
V
FLAG OUTPUT (MAX4836)
Blanking Time (Note 6) tBLANKVOUT + 1V ≤ VIN ≤ 5.5V, OUT = GND 5 10 17 ms
Open-Drain FLAG Output-
Voltage Low
ISINK = 3.2mA, FLAG asserted, VOUT ≥ 1.5V 0.4 V
Open-Drain FLAG Leakage
Current
VFLAG = 5.5V 0.01 1 A
THERMAL PROTECTION
Thermal-Shutdown Temperature Junction temperature rising +165 °C
Thermal-Shutdown Hysteresis15 °C
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
4 _______________________________________________________________________________________
_______________________________________________________________典型工作特性
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= +25°C, unless otherwise noted.)
QUIESCENT CURRENT vs. INPUT VOLTAGE
(NO LOAD)
MAX4836 toc01
VIN (V)
IQ ( A)
54321
20
40
60
80
100
120
0
06
TA = +85°C
TA = -40°C
TA = +25°C
VOUT = 1.5V
QUIESCENT CURRENT vs. INPUT VOLTAGE
(500mA LOAD)
MAX4836 toc02
VIN (V)
IQ ( A)
5432106
TA = +85°C
VOUT = 3.3V
TA = -40°C
100
200
300
400
500
600
700
800
0
TA = +25°C
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX4836 toc03
RESET THRESHOLD OVERDRIVE (mV)
PULSE DURATION ( s)
10
15
30
45
60
75
90
0
1100
RESET ASSERTS
ABOVE THIS LINE
VIN = 3.5V
VOUT = 2.5V
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX4836 toc04
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
400300200100
30
60
90
120
150
180
0
0500
VOUT = 3.3V
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4836 toc05
FREQUENCY (kHz)
PSRR (dB)
1010.1
-70
-60
-50
-40
-30
-20
-10
0
-80
0.01 100
VOUT = 2V
COUT = 3.3 F
ILOAD = 20mA
REGION OF STABLE COUT ESR
vs. LOAD CURRENT
MAX4836 toc06
LOAD CURRENT (mA)
COUT ESR ( )
1
2
3
4
5
6
7
0
VOUT = 1.8V
COUT = 3.3 F
STABLE REGION
450400350300250200150100500500
OUTPUT NOISE vs. FREQUENCY
MAX4836 toc07
FREQUENCY (Hz)
OUTPUT NOISE ( VRMS)
10k1k100
10
20
30
40
50
0
10 100k
VIN = 3V
VOUT = 1.8V
CSS = 10nF
ILOAD = 0
SOFT-START RESPONSE
(CSS = FLOATING)
MAX4836 toc08
VSS
1V/div
VOUT
2V/div
VIN
2V/div
2ms/div
tSS
_______________________________________________________________________________________ 5
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
SOFT-START RESPONSE
(CSS = 0.01 F)
MAX4836 toc09
VSS
1V/div
VOUT
2V/div
VIN
2V/div
2ms/div
tSS
SOFT-START RESPONSE
(CSS = 0.1 F)
MAX4836 toc10
VIN
2V/div
VSS
1V/div
VOUT
2V/div
20ms/div
tSS
LOAD-TRANSIENT RESPONSE
MAX4836 toc11
VOUT
50mV/div
AC-COUPLED
100 s/div
VIN = 4.3V
VOUT = 3.3V
CIN = 0.1 F
COUT = 3.3 F
ILOAD: STEP FROM 10mA TO 100mA
BACK TO 10mA
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
MAX4836 toc12
VOUT
50mV/div
AC-COUPLED
100 s/div
VIN = 3.4V
VOUT = 3.3V
CIN = 0.1 F
COUT = 3.3 F
ILOAD: STEP FROM 10mA TO 100mA
BACK TO 10mA
LINE-TRANSIENT RESPONSE
MAX4836 toc13
VOUT
50mV/div
AC-COUPLED
100 s/div
CIN = 0.1 F
COUT = 3.3 F
VOUT = 3.3V
ILOAD = 10mA
5V
VIN
500mV/div
4.5V
RESET RESPONSE TO VIN
MAX4836 toc14
VRESET
2V/div
VOUT
2V/div
VIN
2V/div
40ms/div
tRESET
CSS = FLOATING
RESET RESPONSE TO VOUT
MAX4836 toc15
VRESET
1V/div
VOUT
1V/div
40ms/div
tRESET
VIN = 3.5V, CSS = FLOATING
RESET RESPONSE TO SHUTDOWN
MAX4836 toc16
VRESET
2V/div
VOUT
2V/div
VSHDN
2V/div
40ms/div
tRESET
VIN = 3.5V, CSS = FLOATING
____________________________________________________________典型工作特性(续)
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= +25°C, unless otherwise noted.)
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
6 _______________________________________________________________________________________
____________________________________________________________典型工作特性(续)
(VIN= VOUT+ 1V, SHDN= IN, COUT= 3.3 F, TA= +25°C, unless otherwise noted.)
FLAG RESPONSE WHEN OUT IS
SHORTED TO GND BLANKING TIME
(IN IS TOGGLED)
MAX4836 toc18
VOUT
1V/div
10ms/div
VIN
2V/div
VFLAG
2V/div
FLAG CONNECTED TO LOGIC SUPPLY
tBLANK
STARTUP IN AN OVERLOAD CONDITION
(CSS NOT CONNECTED)
MAX4836 toc20
VSS
1V/div
VFLAG
2V/div
VOUT
2V/div
2ms/div
tBLANK
VIN
2V/div
tSS
VOUT = 2.5V
ILOAD = ILIMIT MAXIMUM
FLAG CONNECTED TO LOGIC SUPPLY
STARTUP IN AN OVERLOAD CONDITION
(CSS = 0.01 F)
MAX4836 toc21
VSS
1V/div
VFLAG
2V/div
VOUT
2V/div
4ms/div
tBLANK
VIN
2V/div
tSS
VOUT = 2.5V
ILOAD = ILIMIT MAXIMUM
FLAG CONNECTED TO LOGIC SUPPLY
NORMALIZED OUTPUT VOLTAGE
vs. TEMPERATURE
MAX4836 toc22
TEMPERATURE (°C)
NORMALIZED OUTPUT VOLTAGE
603510-15
0.996
0.998
1.000
1.002
1.004
0.994
-40 85
NORMALIZED TO +25°C
ILOAD = 500mA
ILOAD = 300mA
ILOAD = 100mA
FLAG RESPONSE WHEN OUT IS
SHORTED TO GND > BLANKING TIME
(SHDN IS TOGGLED)
MAX4836 toc19
VOUT
1V/div
10ms/div
VSHDN
2V/div
VFLAG
2V/div
FLAG CONNECTED TO LOGIC SUPPLY
tBLANK
____________________________详细说明
MAX4836/MAX4837低压差线性稳压器具有超低静态电
流,并带有集成限流器.这些器件能保证高达500mA的
驱动能力,并稳定在预置输出电压.
MAX4836有一个标志输出,当负载电流超过电流限且
持续时间超过屏蔽时间(tBLANK)时,该输出变低.
MAX4837有一个复位输出,当稳压器输出电压低于复位
门限电压(VRESET)时,该输出变低.VRESET为标称输出
电压的87.5%.图1给出了简化的功能框图,图2给出了
典型应用电路.
FLAG输出(MAX4836)
当调整管流过的电流达到它的输出电流限且持续时间超
过屏蔽时间(tBLANK)时,漏极开路输出FLAG变低,同时
LDO的调整管闭锁.重新上电或刷新SHDN控制(由高到
低,再到高)会使器件退出闭锁状态,并返回到正常工作
状态.
RESET输出(MAX4837)
当出现以下条件之一时,将触发RESET复位输出:
输入电压(VIN)低于输入欠压锁定门限(VUVLO).
输出电压(VOUT)低于复位门限(VRESET).
拉低SHDN.
器件处于热关断状态.
当VOUT> VIN时.
复位条件结束后,RESET在复位超时周期(tRESET)内仍保
持低电平.提供四种RESET超时周期,如Electrical
Characteristics表所示.RESET采用推挽输出结构,见选
择指南.
关断
将SHDN拉低可关断LDO,并将器件的静态电流从90 A
降低到0.1 A.在关断模式下,调整管,控制电路和基准
电路都关闭.将SHDN接到大于VIH的电源电压上可开启
LDO.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
_______________________________________________________________________________________ 7
___________________________________________________________________引脚说明
PIN
SOT23 TDFN
NAME FUNCTION
11 IN
Regulator Power Input. Bypass IN to GND with a 0.1 F ceramic capacitor. Install the bypass
capacitor as close to the device as possible.
2 2 GND Ground
33SHDN
Active-Low Shutdown Input. Drive SHDN low to shutdown the regulator. Drive SHDN high or
connect to IN for normal operation.
FLAG
(MAX4836)
Overcurrent Flag. Open-drain FLAG goes low when the device senses sustained current
exceeding the current-limit threshold for a duration longer than the blanking time. FLAG is high
when SHDN is low or the device is in thermal shutdown.
44
RESET
(MAX4837)
Active-Low Reset Output. Push-pull RESET goes low when the voltage at OUT is below the reset
threshold or when the voltage at OUT is greater than IN. RESET is low when SHDN is low or the
device is in thermal shutdown. After the reset condition terminates, RESET remains low for the
duration of the reset timeout period.
55 SS
Soft-Start Control. Connect a capacitor, CSS, from SS to GND to program the output rise time at
startup. No capacitor from SS to GND gives 1ms output rise time at startup. See the soft-start
response time plots in the Typical Operating Characteristics.
6 6 OUT
Regulator Output. Bypass OUT to GND with a 3.3 F or larger ceramic capacitor. The capacitor's
ESR should be less than 0.2 for stable operation.
—EP EP
Exposed Pad. EP is internally connected to GND. Externally connect EP to GND to provide a low
thermal resistance path from the IC junction to the PC board.
引脚
名称功能
稳压器电源输入.用一个0.1 F陶瓷电容将IN旁路至GND.旁路电容应安装在尽可能靠近器件的
位置.
地
低电平有效关断输入.将SHDN置低可关断稳压器.SHDN接高电平或接至IN可正常工作.
过流标志.当器件检测到电流超过电流门限值,且持续时间超过屏蔽时间时,漏极开路FLAG输出
变低.当SHDN为低或器件处于热关断状态时,FLAG为高.
低电平有效复位输出.当OUT上的电压低于复位门限值或者高于IN引脚上的电压时,推挽输出
RESET变低.当SHDN为低或器件处于热关断状态时,RESET为低电平.复位条件结束后,
在复位超时周期内RESET仍保持低电平.
软启动控制.在SS和GND之间接一个电容CSS,来设置启动时的输出上升时间.SS和GND之间
不接电容时,会在启动时产生1ms的输出上升时间.见典型工作特性中的软启动响应时间图
(soft-start response).
稳压器输出.用一个3.3 F或更大的陶瓷电容将OUT旁路至GND.为了实现稳定工作,电容的ESR
应小于0.2 .
裸露焊盘.EP在内部与GND相连.从外部将EP接至GND,可为IC到PC板之间提供低热阻通路.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
8 _______________________________________________________________________________________
REVERSE-
CURRENT
PROTECTION
PASS
TRANSISTOR
RESET TIMEOUT
(BLANKING PERIOD)
OVERLOAD
PROTECTION
VSS
vFB
VREF
VFB
VREF
ERROR
AMPLIFIER
1.23V
90% x VREF
VREF
VSS = VREF
WHEN SOFT-START
IS COMPLETE
SWITCH OPEN
DURING SOFT-START
VSS
1.23 A
1nF
SWITCH
CLOSED IN
SHUTDOWN
MAX4837 ONLY
THERMAL
PROTECTIONMAX4836/MAX4837
IN
SHDN
RESET
(FLAG)
GND
SS
OUT
900
( ) MAX4836E_ _xyC ONLY.
图1. 功能框图
MAX4836
LOAD
COUT
3.3 F
CSS
ON
OFF
OUT
SS
SHDN
FLAG
IN
GND
MAX4837
LOAD
COUT
3.3 F
CIN
0.1 F
2.5V TO 5.5V
CSS
TO C
ON
OFF
OUT
SS
SHDN
RESET
IN
GND
CIN
0.1 F
2.5V TO 5.5V
TO C
VLOGIC
图2. 典型应用电路
关断放电电路(MAX4837)
在关断模式下,OUT通过900 的内部电阻进行放电.
OUT到IN反向电流
当输出电压大于输入电压时,内部调整管关闭.当VOUT≥
VIN时,为避免对输入电源反向充电,IN电流确保低于
3 A.
电流限制
MAX4836/MAX4837包含一套精确的内部限流电路.即
使OUT与地短接也不会损坏器件.
如果负载电流超过电流限且持续时间超过屏蔽时间(见
FLAG输出部分),MAX4836会发生闭锁.在软启动过程
中,过载条件不会引起器件闭锁.过载条件下,在温度
达到热限制之前,MAX4837将电流保持为限流值;一旦
结温达到+165°C,就会发生热关断.
热关断
当结温(TJ)超过+165°C时,LDO的调整管会关断从而降
低结温.当IC的结温降低了15°C后,LDO的调整管重新
打开,即在持续热过载条件下会产生脉冲输出.
软启动
在上电过程中,软启动确保输出缓慢上升,从而减小了
浪涌峰值电流.请参考典型工作特性中的软启动响应
(soft-start response)时间图.软启动时间(tSS)由下式给
出:
tSS= CSS(ms)
式中CSS的单位为nF.
10nF的软启动电容(CSS)会产生10ms的软启动时间tSS.
内部设置了一个1ms的最小软启动时间,这样即使在SS
引脚和地之间不加任何外部电容的情况下,也能确保输
出缓慢上升.重新上电或者刷新SHDN控制时,器件会
进入软启动模式.
____________________________应用信息
电容选择以及稳压器稳定性
为了能在整个温度范围和负载电流高达500mA的情况下
稳定工作,使用一个ESR <0.2 的3.3 F(最小)陶瓷输出
电容.为降低噪声并改善负载瞬态响应,稳定性和电源
抑制,可使用更大的输出电容,如10 F(需注意一些陶
瓷电容的电容值和ESR会随温度变化而发生较大变化).
X7R电容在整个-40°C到+85°C的工作温度范围内都具有
很好的性能.
为了提高电源抑制能力并改善瞬态响应,可在IN和GND
之间接一个0.1 F的电容.在纯阻性负载或负载电流高达
500mA的情况下,MAX4836/MAX4837都能保持稳定.
15kV ESD保护
在OUT和GND之间接一个3.3 F或更高容值的陶瓷电容
会在OUT端提供15kV(人体模型)ESD保护.电容的ESR
值应小于0.2 .
复位瞬态抑制
复位电路不受短时的VOUT跌落影响.典型工作特性给出
了不会触发复位输出的Maximum Transient Duration vs.
Reset Threshold Overdrive关系曲线图.该曲线图是通过
测试瞬间跌落的输出电压产生的,输出电压从VOUT开始
跌落,并终止在低于复位门限的某个电平上,图中给出
了该电平低于复位门限的幅度(复位门限过驱动).曲线
图给出了在不触发复位脉冲情况下,一个VOUT跌落可以
具有的最大典型脉宽.随着跌落幅度的增大(即比复位门
限低出更大的幅度),最大允许脉宽降低.典型情况下,
一个比复位门限值仅低10mV的VOUT跌落,若持续时间
不超过54 s,则不会触发复位脉冲.
布局
当使用TDFN封装时,将其裸露焊盘接至GND,从而为
IC到印刷电路板之间的热传递提供一个低热阻通路.
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
_______________________________________________________________________________________ 9
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
10 ______________________________________________________________________________________
_____________________________________________________________________________________________选择指南
PART
PIN-
PACKAGE
OUTPUT
CURRENT (mA)
RESET OUTPUT
CONFIGURATION
RESET
(FLAG)
SHUTDOWN
DISCHARGE
LATCH OFF
MAX4836EUTxyC-T 6 SOT23-6 500 Open-DrainFLAGNo Yes
MAX4836ETTxyC-T 6 TDFN-6 500 Open-DrainFLAGNo Yes
MAX4837EUTxyBdd-T 6 SOT23-6 500 Push-PullRESETYes No
MAX4837ETTxyBdd-T 6 TDFN-6 500 Push-PullRESETYes No
器件型号中的后缀'xy'表示标称输出电压.1.8V,2.5V,2.8V,3.0V和3.3V是标准电压选型.若需1.5V至3.3V范围内的其它电压,
请与厂商联系.
表1. 标准输出电压与型号后缀对照指南
xy OUTPUT VOLTAGE (V)
18 1.8
25 2.5
28 2.8
30 3.0
33 3.3
可提供1.5V至3.3V范围内,增量为100mV的非标准输出电压,
供货情况请与厂商联系.
表2. RESET超时周期与型号后缀对照指南
ddRESET TIMEOUT (ms)
D1 3.75
D2 30
D3 225
D4 1800
TOP VIEW
GND
SHDN
1 6 OUT
5SS
IN
MAX4836/
MAX4837
SOT23
2
34RESET
(FLAG)
( ) MAX4836EUTxyC ONLY.
_________________________引脚配置(续)
____________________________芯片信息
TRANSISTOR COUNT: 1575
PROCESS: BiCMOS
TDFN Exposed Pad: Connected to GND
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
______________________________________________________________________________________ 11
6, 8, &10L, DFN THIN.EPS
LCLC
PIN 1
INDEX
AREA
D
E
L
e
L
A
e
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY
E2
DETAIL A
N
F
1
221-0137
PACKAGE OUTLINE, 6, 8, 10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
COMMON DIMENSIONS
SYMBOLMIN. MAX.
A 0.70 0.80
D 2.90 3.10
E 2.90 3.10
A1 0.00 0.05
L0.200.40
PKG. CODEND2E2eJEDEC SPECb[(N/2)-1] x e
PACKAGE VARIATIONS
0.25 MIN.k
A2 0.20 REF.
2.30±0.101.50±0.106T633-1 0.95 BSC MO229 / WEEA1.90 REF
F
2
221-0137
PACKAGE OUTLINE, 6, 8, 10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
0.40±0.05
1.95 REF0.30±0.050.65 BSC2.30±0.108T833-1
2.00 REF0.25±0.050.50 BSC2.30±0.1010T1033-1
2.40 REF0.20±0.03- - - - 0.40 BSC1.70±0.10 2.30±0.1014T1433-1
1.50±0.10
1.50±0.10
MO229 / WEEC
MO229 / WEED-3
0.40 BSC- - - - 0.20±0.03 2.40 REFT1433-2 14 2.30±0.101.70±0.10
___________________________________________________________________封装信息
(本数据资料提供的封装图可能不是最近的规格,如需最近的封装外型信息,请查询www.maxim-ic.com.cn/packages.)
MAX4836/MAX4837
500mA LDO线性稳压器,
带有限流开关
6LSOT.EPS
F
1
121-0058
PACKAGE OUTLINE, SOT-23, 6L
_______________________________________________________________封装信息(续)
(本数据资料提供的封装图可能不是最近的规格,如需最近的封装外型信息,请查询www.maxim-ic.com.cn/packages.)
Maxim不对Maxim产品以外的任何电路使用负责,也不提供其专利许可.Maxim保留在任何时间,没有任何通报的前提下修改产品资料和规格的权利.
12__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
2004 Maxim Integrated Products Printed USA是Maxim Integrated Products, Inc. 的注册商标.
MAXIM北京办事处
北京8328信箱邮政编码100083
免费电话:800 810 0310
电话:010-6201 0598
传真:010-6201 0298
·下一篇：在线仿真器