MAX4836 [MAXIM]

500mA LDO Linear Regulators with Current-Limiting Switch; 500毫安LDO线性稳压器,限流开关
MAX4836
型号: MAX4836
厂家: MAXIM INTEGRATED PRODUCTS    MAXIM INTEGRATED PRODUCTS
描述:

500mA LDO Linear Regulators with Current-Limiting Switch
500毫安LDO线性稳压器,限流开关

稳压器 开关
文件: 总12页 (文件大小:352K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
19-3374; Rev 0; 7/04  
500mA LDO Linear Regulators with  
Current-Limiting Switch  
General Description  
Features  
The MAX4836/MAX4837 family of low-dropout (LDO)  
linear regulators feature an accurate current-limiting  
switch with an integrated FLAG or RESET function. These  
devices operate from 2.5V to 5.5V and deliver up to  
500mA of load current at a preset output voltage. Preset  
output voltage levels are 1.8V/2.5V/2.8V/3.0V/3.3V.  
Guaranteed Minimum 500mA Load Current  
Accurate Current Limit  
Preset Output Voltages: 1.8V/2.5V/2.8V/3.0V/3.3V  
2.5V to 5.5V Supply Voltage Range  
Adjustable Soft-Start  
The MAX4836/MAX4837 offer a programmable soft-  
start control function to eliminate false reset during  
startup. The MAX4836 provides a FLAG function to noti-  
fy the system when the load current exceeds the limit.  
The MAX4837 provides a RESET function to notify the  
system when the output drops below the threshold.  
Additionally, reverse-current protection prevents cur-  
rent flowing from the output to the input. Other features  
include a low 90µA quiescent current, a 0.1µA shut-  
down current.  
Low Dropout Voltage  
Thermal Shutdown  
Reverse-Current Protection  
Shutdown Output Discharge (MAX4837)  
Low 90µA Supply Current  
Ultra-Low 0.1µA Shutdown Current  
The MAX4836/MAX4837 are available in space-saving  
6-pin SOT23 and TDFN packages. Each device is speci-  
fied over the -40°C to +85°C extended temperature  
range. Contact factory for other programmed output volt-  
age versions from 1.5V to 3.3V in 100mV increments.  
FLAG and Latch Off (MAX4836) or RESET  
(MAX4837)  
Tiny SOT23 and TDFN (3mm x 3mm) Packages  
Ordering Information  
For pin-compatible 100mA versions of this device, refer  
to the MAX4832/MAX4833. For pin-compatible 250mA  
versions of this device, refer to the MAX4834/MAX4835.  
PART  
TEMP RANGE PIN-PACKAGE  
-40°C to +85°C 6 SOT23-6  
-40°C to +85°C 6 TDFN-6  
-40°C to +85°C 6 SOT23-6  
-40°C to +85°C 6 TDFN-6  
MAX4836EUTxy_-T*  
MAX4836ETTxy_-T  
MAX4837EUTxy_dd-T*  
MAX4837ETTxy_dd-T  
Applications  
SDIO Ports and Devices  
USB Ports and Devices  
Notebook Computers  
Cell Phones  
PDAs and Palmtop Devices GPS Systems  
Note: “xy” are placeholders for the output voltage levels of the  
devices. Insert the values found in Table 1 at the end of this doc-  
ument in the place of “xy”. The “_” is a placeholder for either the  
RESET or the FLAG feature. Insert “B” in the place of “_” for  
RESET and “C” for FLAG. “dd” is a placeholder for the reset  
timeout period. Insert the values found in Table 2 in the place of  
“dd.” For example, MAX4837EUT18BD2 has a 1.8V output volt-  
age, RESET feature, and a 30ms reset timeout period. Note that  
“dd” applies only to the devices with RESET option and does not  
apply to the devices with FLAG option. For devices with the  
FLAG option, leave dd blank. Standard versions require a mini-  
mum order increment of 2.5k units. Nonstandard versions must  
be ordered in 10k unit increments. Contact factory for availability.  
*Future product—contact factory for availability.  
Pin Configurations  
TOP VIEW  
1
IN  
OUT  
SS  
6
5
4
2
3
GND  
MAX4836/MAX4837  
RESET  
(FLAG)  
SHDN  
EXPOSED PADDLE  
Tables 1 and 2 and Selector Guide appear at end of data  
sheet.  
TDFN  
( ) MAX4836ETTxyC ONLY.  
Pin Configurations continued at end of data sheet.  
________________________________________________________________ Maxim Integrated Products  
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at  
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.  
500mA LDO Linear Regulators with  
Current-Limiting Switch  
ABSOLUTE MAXIMUM RATINGS  
IN, SHDN, FLAG, OUT to GND ................................-0.3V to +6V  
RESET to GND .........................................-0.3V to (V + 0.3V)  
Continuous Power Dissipation (T = +70°C)  
6-Pin SOT23 (derate 9.1mW/°C above +70°C)................727mW  
A
OUT  
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  
SS to GND ...................................................-0.3V to (V + 0.3V)  
IN  
IN to OUT............................................................................... 6V  
OUT Short Circuit to GND ..........................................Continuous  
All Pins ESD Handling (Human Body Model).........................2kV  
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.  
ELECTRICAL CHARACTERISTICS  
(V = V  
+ 1V, SHDN = IN, C = 3.3µF, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)  
OUT A A  
IN  
OUT  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
Operating Voltage  
V
2.5  
5.5  
V
IN  
Input Undervoltage Lockout  
Threshold  
V
V
rising  
IN  
2.00  
2.25  
V
UVLO  
Input Undervoltage Lockout  
Threshold Hysteresis  
50  
90  
mV  
SHDN = IN, I  
SHDN = IN, I  
= 0  
150  
OUT  
= 0,  
(nominal)  
OUT  
OUT  
150  
Quiescent Current  
I
µA  
Q
V
< V < V  
UVLO  
IN  
SHDN = GND, I  
= 0  
0.1  
2
OUT  
T
T
= +25°C  
200  
300  
330  
A
Dropout Voltage (Note 2)  
Output Voltage Accuracy  
I
= 500mA  
mV  
OUT  
= -40°C to +85°C  
A
I
I
= 1mA to 500mA, T = +25°C  
-1.3  
+1.3  
+2  
OUT  
A
%V  
NOM  
= 1mA to 500mA, T = -40°C to +85°C  
-2  
OUT  
A
Output Current  
I
500  
540  
mA  
OUT  
Output Current Limit  
V
V
= 0V  
660  
2
mA  
µA  
OUT  
OUT  
Reverse Current at V  
= 5.5V, V = 0V to V  
IN  
0.1  
1
IN  
OUT  
C
C
C
= not connected  
= 0.01µF  
0.5  
4
2.0  
15  
SS  
SS  
SS  
Soft-Start Time (Note 3)  
Line Regulation (Note 4)  
t
ms  
10  
100  
SS  
= 0.1µF  
40  
150  
T
T
= +25°C  
-0.04  
+0.02 +0.065  
%V  
V
+ 0.5V < V  
LOAD  
<
A
/
OUT  
IN  
NOM  
V
5.5V, I  
= 100µA  
= -40°C to +85°C -0.05  
+ 1V  
+0.03  
1.3  
+0.08  
A
Load Regulation  
100µA < I  
< 500mA, V = V  
%V  
LOAD  
IN  
OUT  
NOM  
Output Noise  
10Hz to 100kHz, C = 0.01µF  
SS  
70  
µV  
RMS  
SHUTDOWN INPUT (SHDN)  
OUT Discharge Resistance in  
Shutdown (MAX4837)  
SHDN = GND  
900  
30  
SHDN Input-Voltage High  
SHDN Input-Voltage Low  
SHDN Input Hysteresis  
V
1.4  
V
V
IH  
V
0.5  
IL  
mV  
nA  
SHDN Input Leakage Current  
SHDN = IN or GND  
-100  
+100  
2
_______________________________________________________________________________________  
500mA LDO Linear Regulators with  
Current-Limiting Switch  
ELECTRICAL CHARACTERISTICS (continued)  
(V = V  
+ 1V, SHDN = IN, C = 3.3µF, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)  
OUT A A  
IN  
OUT  
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
RESET OUTPUT (MAX4837)  
0.85 x 0.875 x 0.90 x  
RESET Threshold  
V
V
RESET  
V
V
V
OUT  
OUT  
OUT  
OUT Drop to RESET Delay  
(Note 5)  
t
35  
µs  
OR  
D1 timing option  
2.5  
20  
3.75  
30  
5.0  
40  
D2 timing option  
D3 timing option  
D4 timing option  
RESET Timeout Period  
t
ms  
RESET  
150  
1200  
225  
1800  
300  
2400  
0.3  
V
1.0V, I  
= 50µA, RESET asserted  
= 3.2mA, RESET  
OUT  
SINK  
RESET Output-Voltage Low  
RESET Output-Voltage High  
V
V
V
1.5V, I  
OUT  
SINK  
0.4  
asserted  
2.0V, I  
V
500µA,  
0.8 x  
OUT  
SOURCE  
RESET deasserted  
V
OUT  
FLAG OUTPUT (MAX4836)  
Blanking Time (Note 6)  
t
V
+ 1V V 5.5V, OUT = GND  
5
10  
17  
ms  
V
BLANK  
OUT  
IN  
Open-Drain FLAG Output-  
Voltage Low  
I
= 3.2mA, FLAG asserted, V  
1.5V  
OUT  
0.4  
SINK  
Open-Drain FLAG Leakage  
Current  
V
= 5.5V  
0.01  
1
µA  
FLAG  
THERMAL PROTECTION  
Thermal-Shutdown Temperature  
Thermal-Shutdown Hysteresis  
Junction temperature rising  
+165  
15  
°C  
°C  
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 V to V  
when V  
is 2% below its nominal value. The nominal output voltage is  
IN  
OUT  
OUT  
measured from V  
to GND when V is 1V greater than V  
. Defined only for V  
2.5V.  
OUT  
IN  
OUT  
OUT  
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 V < 2V, V must be above 2.5V.  
OUT  
IN  
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  
FLAG issued is t + t  
.
SS  
BLANK  
_______________________________________________________________________________________  
3
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Typical Operating Characteristics  
(V = V  
IN  
+ 1V, SHDN = IN, C  
= 3.3µF, T = +25°C, unless otherwise noted.)  
OUT A  
OUT  
QUIESCENT CURRENT vs. INPUT VOLTAGE  
(NO LOAD)  
MAXIMUM TRANSIENT DURATION  
vs. RESET THRESHOLD OVERDRIVE  
QUIESCENT CURRENT vs. INPUT VOLTAGE  
(500mA LOAD)  
120  
100  
80  
60  
40  
20  
0
90  
75  
60  
45  
30  
15  
0
800  
700  
600  
500  
400  
300  
200  
100  
0
T
= +85°C  
A
T
= +85°C  
A
RESET ASSERTS  
ABOVE THIS LINE  
T
= +25°C  
A
T
= +25°C  
A
T
= -40°C  
A
T
= -40°C  
A
V
OUT  
= 3.5V  
= 2.5V  
IN  
V
= 1.5V  
OUT  
V
V
= 3.3V  
OUT  
0
1
2
3
4
5
6
1
10  
RESET THRESHOLD OVERDRIVE (mV)  
100  
0
1
2
3
4
5
6
V
(V)  
IN  
V (V)  
IN  
POWER-SUPPLY REJECTION RATIO  
vs. FREQUENCY  
REGION OF STABLE C  
ESR  
OUT  
DROPOUT VOLTAGE vs. LOAD CURRENT  
vs. LOAD CURRENT  
0
-10  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
180  
150  
120  
90  
7
6
5
4
3
2
1
0
V
= 3.3V  
V
= 2V  
V
= 1.8V  
OUT  
OUT  
OUT  
C
= 3.3µF  
= 20mA  
OUT  
I
LOAD  
C
= 3.3µF  
OUT  
STABLE REGION  
60  
30  
0
0.01  
0.1  
1
10  
100  
0
100  
200  
300  
400  
500  
0
50 100 150 200 250 300 350 400 450 500  
LOAD CURRENT (mA)  
FREQUENCY (kHz)  
LOAD CURRENT (mA)  
SOFT-START RESPONSE  
(C = FLOATING)  
SS  
OUTPUT NOISE vs. FREQUENCY  
MAX4836 toc08  
50  
V
= 3V  
IN  
V
C
= 1.8V  
= 10nF  
OUT  
SS  
40  
30  
20  
10  
0
V
IN  
I
= 0  
LOAD  
2V/div  
V
t
OUT  
SS  
2V/div  
V
SS  
1V/div  
2ms/div  
10  
100  
1k  
10k  
100k  
FREQUENCY (Hz)  
4
_______________________________________________________________________________________  
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Typical Operating Characteristics (continued)  
(V = V  
IN  
+ 1V, SHDN = IN, C = 3.3µF, T = +25°C, unless otherwise noted.)  
OUT A  
OUT  
SOFT-START RESPONSE  
SOFT-START RESPONSE  
LOAD-TRANSIENT RESPONSE  
(C = 0.01µF)  
(C = 0.1µF)  
SS  
SS  
MAX4836 toc11  
MAX4836 toc09  
MAX4836 toc10  
V
V
C
C
= 4.3V  
IN  
= 3.3V  
= 0.1µF  
= 3.3µF  
OUT  
V
IN  
IN  
V
IN  
2V/div  
OUT  
2V/div  
I
: STEP FROM 10mA TO 100mA  
LOAD  
BACK TO 10mA  
V
t
OUT  
SS  
V
OUT  
50mV/div  
AC-COUPLED  
2V/div  
V
t
OUT  
SS  
2V/div  
V
SS  
V
SS  
1V/div  
1V/div  
100µs/div  
2ms/div  
20ms/div  
LOAD-TRANSIENT RESPONSE  
NEAR DROPOUT  
LINE-TRANSIENT RESPONSE  
RESET RESPONSE TO V  
IN  
MAX4836 toc13  
MAX4836 toc14  
MAX4836 toc12  
C
= FLOATING  
V
V
C
C
= 3.4V  
SS  
IN  
= 3.3V  
= 0.1µF  
= 3.3µF  
OUT  
IN  
5V  
V
IN  
OUT  
V
2V/div  
IN  
I
: STEP FROM 10mA TO 100mA  
LOAD  
500mV/div  
4.5V  
BACK TO 10mA  
V
OUT  
50mV/div  
AC-COUPLED  
V
V
OUT  
OUT  
2V/div  
50mV/div  
AC-COUPLED  
C
C
V
= 0.1µF  
= 3.3µF  
IN  
OUT  
OUT  
V
RESET  
= 3.3V  
t
RESET  
2V/div  
I
= 10mA  
LOAD  
100µs/div  
40ms/div  
100µs/div  
RESET RESPONSE TO V  
RESET RESPONSE TO SHUTDOWN  
MAX4836 toc16  
OUT  
MAX4836 toc15  
V
= 3.5V, C = FLOATING  
SS  
V
= 3.5V, C = FLOATING  
SS  
IN  
IN  
V
SHDN  
2V/div  
V
OUT  
1V/div  
V
OUT  
2V/div  
V
RESET  
t
RESET  
1V/div  
V
RESET  
t
RESET  
2V/div  
40ms/div  
40ms/div  
_______________________________________________________________________________________  
5
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Typical Operating Characteristics (continued)  
(V = V  
IN  
+ 1V, SHDN = IN, C  
= 3.3µF, T = +25°C, unless otherwise noted.)  
OUT A  
OUT  
FLAG RESPONSE WHEN OUT IS  
SHORTED TO GND > BLANKING TIME  
FLAG RESPONSE WHEN OUT IS  
SHORTED TO GND > BLANKING TIME  
FLAG RESPONSE WHEN OUT IS  
SHORTED TO GND < BLANKING TIME  
(IN IS TOGGLED)  
(SHDN IS TOGGLED)  
MAX4836 toc17  
MAX4836 toc18  
MAX4836 toc19  
V
V
V
OUT  
1V/div  
OUT  
OUT  
2V/div  
1V/div  
t
BLANK  
V
V
FLAG  
2V/div  
FLAG  
t
BLANK  
2V/div  
I
OUT  
200mA/div  
V
V
SHDN  
IN  
2V/div  
2V/div  
V
FLAG  
5V/div  
FLAG CONNECTED TO LOGIC SUPPLY  
10ms/div  
FLAG CONNECTED TO LOGIC SUPPLY  
10ms/div  
1ms/div  
NORMALIZED OUTPUT VOLTAGE  
vs. TEMPERATURE  
STARTUP IN AN OVERLOAD CONDITION  
(C NOT CONNECTED)  
STARTUP IN AN OVERLOAD CONDITION  
(C = 0.01µF)  
SS  
SS  
MAX4836 toc20  
MAX4836 toc21  
1.004  
1.002  
1.000  
0.998  
0.996  
0.994  
NORMALIZED TO +25°C  
V
V
IN  
2V/div  
IN  
2V/div  
I
= 500mA  
LOAD  
V
V
OUT  
2V/div  
OUT  
t
t
BLANK  
BLANK  
2V/div  
t
t
SS  
SS  
I
= 100mA  
LOAD  
V
V
FLAG  
2V/div  
FLAG  
I
= 300mA  
LOAD  
2V/div  
V
V
SS  
1V/div  
SS  
1V/div  
-40  
-15  
10  
35  
60  
85  
2ms/div  
MAXIMUM  
4ms/div  
= I MAXIMUM  
LOAD LIMIT  
V
= 2.5V  
= I  
V
I
= 2.5V  
OUT  
OUT  
TEMPERATURE (°C)  
I
LOAD LIMIT  
FLAG CONNECTED TO LOGIC SUPPLY  
FLAG CONNECTED TO LOGIC SUPPLY  
6
_______________________________________________________________________________________  
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Pin Description  
PIN  
NAME  
FUNCTION  
SOT23 TDFN  
Regulator Power Input. Bypass IN to GND with a 0.1µF ceramic capacitor. Install the bypass  
capacitor as close to the device as possible.  
1
2
3
1
2
3
IN  
GND  
SHDN  
Ground  
Active-Low Shutdown Input. Drive SHDN low to shutdown the regulator. Drive SHDN high or  
connect to IN for normal operation.  
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.  
FLAG  
(MAX4836)  
4
5
4
5
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.  
RESET  
(MAX4837)  
Soft-Start Control. Connect a capacitor, C , from SS to GND to program the output rise time at  
SS  
startup. No capacitor from SS to GND gives 1ms output rise time at startup. See the soft-start  
SS  
response time plots in the Typical Operating Characteristics.  
Regulator Output. Bypass OUT to GND with a 3.3µF or larger ceramic capacitor. The capacitor’s  
ESR should be less than 0.2for stable operation.  
6
6
OUT  
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.  
EP  
RESET Output (MAX4837)  
Detailed Description  
The RESET output asserts when one of the following  
The MAX4836/MAX4837 are ultra-low quiescent current,  
low-dropout linear regulators with an integrated current  
limiter. These devices guarantee up to 500mA drive  
capabilities and regulate the preset output voltage.  
conditions occurs:  
The input voltage (V ) is below the input undervolt-  
IN  
age lockout threshold (V ).  
UVLO  
The output voltage (V  
) is below the reset thresh-  
The MAX4836 has a flag output that asserts low when  
the load current exceeds the current limit for more than  
OUT  
old (V  
).  
RESET  
the blanking time (t  
). The MAX4837 has a reset  
BLANK  
SHDN is pulled low.  
The device is in thermal shutdown.  
When V > V  
output that asserts low when the regulator output volt-  
age is below the reset threshold voltage (V ).  
RESET  
V
is 87.5% of the nominal output voltage. Figure 1  
OUT  
IN.  
RESET  
shows the simplified functional diagram and Figure 2  
shows the typical application circuits.  
RESET remains low for the reset timeout period (t  
)
RESET  
after reset conditions are terminated. There are four  
RESET timeout periods available as shown in the  
Electrical Characteristics table. RESET is available in a  
push-pull configuration as shown in the Selector Guide.  
FLAG Output (MAX4836)  
The open-drain FLAG output goes low and the LDO’s  
pass transistor is latched off when the current in the  
pass transistor is at its output current limit for more than  
Shutdown  
Pull SHDN low to shut down the LDO and reduce the  
quiescent current consumption of the device from 90µA  
to 0.1µA. In shutdown mode, the pass transistor, con-  
trol circuit, and reference circuit are turned off. Connect  
the blanking time (t  
). Cycling IN or SHDN (high to  
BLANK  
low to high) brings the device out of its latched-off state  
and back into normal operation.  
SHDN to a supply voltage greater than V to turn on  
IH  
the LDO.  
_______________________________________________________________________________________  
7
500mA LDO Linear Regulators with  
Current-Limiting Switch  
THERMAL  
PROTECTION  
MAX4836/MAX4837  
PASS  
TRANSISTOR  
REVERSE-  
CURRENT  
IN  
OUT  
PROTECTION  
ERROR  
AMPLIFIER  
MAX4837 ONLY  
V
SS  
900  
v
FB  
SWITCH  
CLOSED IN  
SHUTDOWN  
OVERLOAD  
PROTECTION  
V
REF  
1.23V  
V
REF  
SHDN  
SWITCH OPEN  
DURING SOFT-START  
1.23µA  
V
= V  
REF  
SS  
V
REF  
WHEN SOFT-START  
IS COMPLETE  
V
FB  
RESET  
(FLAG)  
RESET TIMEOUT  
V
SS  
90% x V  
REF  
SS  
(BLANKING PERIOD)  
1nF  
GND  
( ) MAX4836E_ _xyC ONLY.  
Figure 1. Functional Diagram  
IN  
OUT  
IN  
OUT  
C
0.1µF  
C
3.3µF  
C
0.1µF  
C
OUT  
3.3µF  
IN  
OUT  
IN  
2.5V TO 5.5V  
2.5V TO 5.5V  
V
LOGIC  
LOAD  
LOAD  
MAX4836  
MAX4837  
SS  
SS  
TO µC  
FLAG  
TO µC  
RESET  
SHDN  
C
C
SS  
SS  
ON  
ON  
SHDN  
GND  
GND  
OFF  
OFF  
Figure 2. Typical Application Circuits  
_______________________________________________________________________________________  
8
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Shutdown Discharge (MAX4837)  
Applications Information  
Capacitor Selection and Regulator  
Stability  
OUT discharges through a 900internal resistor during  
shutdown mode.  
Reverse OUT to IN Current  
When the output voltage is greater than the input volt-  
age, the internal pass transistor turns off. To avoid  
reverse-charging the input source, the current at IN is  
For stable operation over the full temperature range and  
with load currents up to 500mA, use a 3.3µF (min)  
ceramic output capacitor with an ESR <0.2. To reduce  
noise and improve load transient response, stability, and  
power-supply rejection, use larger output capacitor  
values such as 10µF (note that some ceramic capacitors  
exhibit large capacitance and ESR variation with temper-  
ature). X7R capacitors provide good performance over  
the -40°C to +85°C operating temperature range.  
guaranteed to be below 3µA when V  
V .  
IN  
OUT  
Current Limit  
The MAX4836/MAX4837 include an accurate internal  
current-limiting circuit. OUT can be shorted to ground  
indefinitely without damaging the part.  
To improve power-supply rejection and transient  
response, use a 0.1µF capacitor between IN and GND.  
The MAX4836/MAX4837 remain stable with purely  
resistive loads or current loads up to 500mA.  
The MAX4836 latches off if the load current exceeds the  
current limit for more than the blanking time (see the  
FLAG Output section). During soft-start, the device does  
not latch off to an overload condition. During an overload  
condition, the MAX4837 holds the current at current limit  
until the thermal limit is reached. Once the junction tem-  
perature reaches +165°C, thermal shutdown occurs.  
15kV Operational ESD Protection  
A 3.3µF or higher value ceramic capacitor from OUT to  
GND provides a 15kV (Human Body Model) protection  
at OUT. The ESR value of the capacitor should be less  
than 0.2.  
Thermal Shutdown  
When the junction temperature (T ) exceeds +165°C,  
J
the LDO’s pass transistor turns off allowing the junction  
to cool. The LDO’s pass transistor turns on again after  
the IC’s junction temperature cools by 15°C, resulting in  
a pulsed output during continuous thermal-overload  
conditions.  
Reset Transient Immunity  
The reset circuit is relatively immune to short duration,  
falling V  
transients. The Typical Operating  
OUT  
Characteristics show a graph of the Maximum Transient  
Duration vs. Reset Threshold Overdrive for which reset is  
not asserted. The graph was produced using falling V  
OUT  
Soft-Start  
During power-up, the soft-start ensures that the output  
ramps up slowly reducing inrush current peaks. See  
the soft-start response time plots in the Typical  
transients starting at V  
and ending below the reset  
OUT  
threshold by the magnitude indicated (reset threshold  
overdrive). The graph shows the maximum pulse width  
that a falling V  
transient can typically have without  
OUT  
Operating Characteristics. The soft-start time (t ) is  
SS  
triggering the reset pulse. As the amplitude of the tran-  
sient increases (i.e., goes further below the reset thresh-  
old), the maximum allowable pulse width decreases.  
given by the following equation:  
t
SS  
= C (ms)  
SS  
Typically, a V  
transient that goes only 10mV below the  
reset threshold and lasts up to 54µs does not trigger a  
reset pulse.  
where C is in nF.  
OUT  
SS  
A soft-start capacitor (C ) of 10nF gives a 10ms t . A  
SS  
SS  
1ms minimum soft-start time is fixed internally to ensure  
that the output rises slowly even without any external  
capacitor at SS pin to ground. The device is in soft-start  
mode when either the voltage at IN or SHDN is cycled  
high to low to high.  
Layout  
When using the TDFN package, connect its exposed  
paddle to GND to provide a low thermal resistance  
path for heat transfer from the IC junction to the printed  
circuit board.  
_______________________________________________________________________________________  
9
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Selector Guide  
PIN-  
OUTPUT  
RESET OUTPUT  
CONFIGURATION  
RESET  
(FLAG)  
SHUTDOWN  
DISCHARGE  
PART  
LATCH OFF  
PACKAGE CURRENT (mA)  
MAX4836EUTxyC-T  
MAX4836ETTxyC-T  
MAX4837EUTxyBdd-T  
MAX4837ETTxyBdd-T  
6 SOT23-6  
6 TDFN-6  
6 SOT23-6  
6 TDFN-6  
500  
500  
500  
500  
Open-Drain  
Open-Drain  
Push-Pull  
FLAG  
FLAG  
No  
No  
Yes  
Yes  
No  
RESET  
RESET  
Yes  
Yes  
Push-Pull  
No  
Suffix ‘xy’ in the part number stands for nominal output voltage. 1.8V, 2.5V, 2.8V, 3.0V, 3.3V are the standard options. For other voltages  
between 1.5V to 3.3V, contact factory.  
Table 1. Standard Output Voltage Suffix  
Guide  
Pin Configurations (continued)  
TOP VIEW  
xy  
18  
25  
28  
30  
33  
OUTPUT VOLTAGE (V)  
1.8  
2.5  
2.8  
3.0  
3.3  
IN  
GND  
1
2
3
6
5
4
OUT  
SS  
MAX4836/  
MAX4837  
RESET  
(FLAG)  
Nonstandard output voltages from 1.5V to 3.3V are available in  
100mV increments. Contact factory for availability.  
SHDN  
SOT23  
RESET  
Table 2.  
Guide  
Timeout Period Suffix  
( ) MAX4836EUTxyC ONLY.  
dd  
D1  
D2  
D3  
D4  
RESET TIMEOUT (ms)  
Chip Information  
3.75  
30  
TRANSISTOR COUNT: 1575  
225  
1800  
PROCESS: BiCMOS  
TDFN Exposed Pad: Connected to GND  
10 ______________________________________________________________________________________  
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Package Information  
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information  
go to www.maxim-ic.com/packages.)  
D
N
PIN 1  
INDEX  
AREA  
E
E2  
DETAIL A  
C
C
L
L
L
L
A
e
e
PACKAGE OUTLINE, 6, 8, 10 & 14L,  
TDFN, EXPOSED PAD, 3x3x0.80 mm  
1
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY  
21-0137  
F
2
COMMON DIMENSIONS  
SYMBOL  
MIN.  
0.70  
2.90  
2.90  
0.00  
0.20  
MAX.  
0.80  
3.10  
3.10  
0.05  
0.40  
A
D
E
A1  
L
k
0.25 MIN.  
0.20 REF.  
A2  
PACKAGE VARIATIONS  
PKG. CODE  
T633-1  
N
6
D2  
E2  
e
JEDEC SPEC  
b
[(N/2)-1] x e  
1.50 0.10 2.30 0.10 0.95 BSC  
1.50 0.10 2.30 0.10 0.65 BSC  
MO229 / WEEA  
MO229 / WEEC  
0.40 0.05  
0.30 0.05  
1.90 REF  
1.95 REF  
2.00 REF  
2.40 REF  
2.40 REF  
T833-1  
8
T1033-1  
T1433-1  
T1433-2  
10  
14  
14  
1.50 0.10 2.30 0.10 0.50 BSC MO229 / WEED-3 0.25 0.05  
1.70 0.10 2.30 0.10 0.40 BSC  
1.70 0.10 2.30 0.10 0.40 BSC  
- - - -  
- - - -  
0.20 0.03  
0.20 0.03  
PACKAGE OUTLINE, 6, 8, 10 & 14L,  
TDFN, EXPOSED PAD, 3x3x0.80 mm  
2
21-0137  
F
2
______________________________________________________________________________________ 11  
500mA LDO Linear Regulators with  
Current-Limiting Switch  
Package Information (continued)  
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information  
go to www.maxim-ic.com/packages.)  
PACKAGE OUTLINE, SOT-23, 6L  
1
21-0058  
F
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are  
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.  
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600  
© 2004 Maxim Integrated Products  
Printed USA  
is a registered trademark of Maxim Integrated Products.  

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