19-3373; Rev 0; 7/04
250mA LDO Linear Regulators with
Current-Limiting Switch
General Description
The MAX4834/MAX4835 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
250mA of load current at a preset output voltage. Preset
output voltage levels are 1.8V/2.5V/2.8V/3.0V/3.3V.
The MAX4834/MAX4835 offer a programmable soft-
start control function to eliminate false reset during
startup. The MAX4834 provides a
FLAG
function to noti-
fy the system when the load current exceeds the limit.
The MAX4835 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.
The MAX4834/MAX4835 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.
For pin-compatible 100mA versions of this device, refer
to the MAX4832/MAX4833. For pin-compatible 500mA
versions of this device, refer to the MAX4836/MAX4837.
♦
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
♦
Low Dropout Voltage
♦
Thermal Shutdown
♦
Reverse-Current Protection
♦
Shutdown Output Discharge (MAX4835)
♦
Low 90µA Supply Current
♦
Ultra-Low 0.1µA Shutdown Current
♦
FLAG
and Latch Off (MAX4834) or
RESET
(MAX4835)
♦
Tiny SOT23 and TDFN (3mm x 3mm) Packages
Features
♦
Guaranteed Minimum 250mA Load Current
MAX4834/MAX4835
Ordering Information
PART
MAX4834EUTxy_-T*
MAX4834ETTxy_-T
MAX4835EUTxy_dd-T*
MAX4835ETTxy_dd-T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
6 SOT23-6
6 TDFN-6
6 SOT23-6
6 TDFN-6
Applications
SDIO Ports and Devices
USB Ports and Devices
PDAs and Palmtop Devices
Notebook Computers
Cell Phones
GPS Systems
Pin Configurations
TOP VIEW
IN
1
6
5
4
OUT
SS
RESET
(FLAG)
GND
SHDN
2
3
MAX4834/MAX4835
EXPOSED PADDLE
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, MAX4835EUT18BD2 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.
Tables 1 and 2 and Selector Guide appear at end of data
sheet.
TDFN
( ) MAX4834ETTxyC 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.
250mA LDO Linear Regulators with
Current-Limiting Switch
MAX4834/MAX4835
ABSOLUTE MAXIMUM RATINGS
IN,
SHDN, FLAG,
OUT to GND ................................-0.3V to +6V
RESET
to GND .........................................-0.3V to (V
OUT
+ 0.3V)
SS to GND ...................................................-0.3V to (V
IN
+ 0.3V)
IN to OUT ...............................................................................±6V
OUT Short Circuit to GND ..........................................Continuous
All Pins ESD Handling (Human Body Model).........................2kV
Continuous Power Dissipation (T
A
= +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
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
IN
= V
OUT
+ 1V,
SHDN
= IN, C
OUT
= 3.3µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Operating Voltage
Input Undervoltage Lockout
Threshold
Input Undervoltage Lockout
Threshold Hysteresis
SHDN
= IN, I
OUT
= 0
Quiescent Current
I
Q
SHDN
= IN, I
OUT
= 0,
V
UVLO
< V
IN
< V
OUT
(nominal)
SHDN
= GND, I
OUT
= 0
Dropout Voltage (Note 2)
Output Voltage Accuracy
Output Current
Output Current Limit
Reverse Current at V
IN
Soft-Start Time (Note 3)
t
SS
I
OUT
V
OUT
= 0V
V
OUT
= 5.5V, V
IN
= 0V to V
OUT
C
SS
= not connected
C
SS
= 0.01µF
C
SS
= 0.1µF
Line Regulation (Note 4)
Load Regulation
Output Noise
SHUTDOWN INPUT (SHDN)
OUT Discharge Resistance in
Shutdown (MAX4835)
SHDN
Input-Voltage High
SHDN
Input-Voltage Low
SHDN
Input Hysteresis
SHDN
Input Leakage Current
SHDN
= IN or GND
-100
V
IH
V
IL
30
+100
SHDN
= GND
1.4
0.5
900
Ω
V
V
mV
nA
V
OUT
+ 0.5V < V
IN
<
5.5V, I
LOAD
= 100µA
T
A
= +25°C
T
A
= -40°C to +85°C
0.5
4
40
-0.04
-0.05
I
OUT
= 250mA
T
A
= +25°C
T
A
= -40°C to +85°C
-1.3
-2
250
270
0.1
1
10
100
+0.02
+0.03
1.3
70
330
2
2.0
15
150
+0.065 %V
NOM
/
V
+0.08
%V
NOM
µV
RMS
ms
SYMBOL
V
IN
V
UVLO
V
IN
rising
CONDITIONS
MIN
2.5
2.00
50
90
150
0.1
103
2
140
165
+1.3
+2
mV
%V
NOM
mA
mA
µA
150
µA
TYP
MAX
5.5
2.25
UNITS
V
V
mV
I
OUT
= 1mA to 250mA, T
A
= +25°C
I
OUT
= 1mA to 250mA, T
A
= -40°C to +85°C
100µA < I
LOAD
< 250mA, V
IN
= V
OUT
+ 1V
10Hz to 100kHz, C
SS
= 0.01µF
2
_______________________________________________________________________________________
250mA LDO Linear Regulators with
Current-Limiting Switch
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
OUT
+ 1V,
SHDN
= IN, C
OUT
= 3.3µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
RESET
OUTPUT (MAX4835)
RESET
Threshold
OUT Drop to RESET Delay
(Note 5)
V
RESET
t
OR
D1 timing option
RESET
Timeout Period
t
RESET
D2 timing option
D3 timing option
D4 timing option
V
OUT
≥
1.0V, I
SINK
= 50µA,
RESET
asserted
RESET
Output-Voltage Low
V
OUT
≥
1.5V, I
SINK
= 3.2mA,
RESET
asserted
V
OUT
≥
2.0V, I
SOURCE
≤
500µA,
RESET
deasserted
t
BLANK
V
OUT
+ 1V
≤
V
IN
≤
5.5V, OUT = GND
I
SINK
= 3.2mA,
FLAG
asserted, V
OUT
≥
1.5V
V
FLAG
= 5.5V
0.01
0.8 x
V
OUT
5
10
17
0.4
1
2.5
20
150
1200
0.85 x
V
OUT
0.875 x
V
OUT
35
3.75
30
225
1800
5.0
40
300
2400
0.3
0.4
V
ms
0.90 x
V
OUT
V
µs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX4834/MAX4835
RESET
Output-Voltage High
FLAG
OUTPUT (MAX4834)
Blanking Time (Note 6)
Open-Drain
FLAG
Output-
Voltage Low
Open-Drain
FLAG
Leakage
Current
THERMAL PROTECTION
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
V
ms
V
µA
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
IN
to V
OUT
when V
OUT
is 2% below its nominal value. The nominal output voltage is
measured from V
OUT
to GND when V
IN
is 1V greater than V
OUT
. Defined only for V
OUT
≥
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 V
OUT
< 2V, V
IN
must 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
FLAG
issued is t
SS
+ t
BLANK
.
_______________________________________________________________________________________
3
250mA LDO Linear Regulators with
Current-Limiting Switch
MAX4834/MAX4835
Typical Operating Characteristics
(V
IN
= V
OUT
+ 1V,
SHDN
= IN, C
OUT
= 3.3µF, T
A
= +25°C, unless otherwise noted.)
QUIESCENT CURRENT vs. INPUT VOLTAGE
(NO LOAD)
MAX4834 toc01
QUIESCENT CURRENT vs. INPUT VOLTAGE
(250mA LOAD)
MAX4834 toc02
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX4834 toc03
120
T
A
= +85°C
100
80
I
Q
(µA)
60
T
A
= -40°C
40
20
V
OUT
= 1.5V
0
0
1
2
3
V
IN
(V)
4
5
6
T
A
= +25°C
500
T
A
= +85°C
400
90
75
PULSE DURATION (µs)
60
45
30
15
RESET ASSERTS
ABOVE THIS LINE
I
Q
(µA)
300
T
A
= +25°C
200
T
A
= -40°C
100
V
OUT
= 3.3V
0
0
1
2
3
V
IN
(V)
4
5
6
0
1
10
V
IN
= 3.5V
V
OUT
= 2.5V
100
RESET THRESHOLD OVERDRIVE (mV)
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX4834 toc04
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4834 toc05
REGION OF STABLE C
OUT
ESR
vs. LOAD CURRENT
V
OUT
= 1.8V
6
5
C
OUT
ESR (Ω)
4
STABLE REGION
3
2
1
0
C
OUT
= 3.3µF
MAX4834 toc06
100
V
OUT
= 3.3V
DROPOUT VOLTAGE (mV)
80
0
-10
-20
PSRR (dB)
V
OUT
= 2V
C
OUT
= 3.3µF
I
LOAD
= 20mA
7
60
-30
-40
-50
-60
-70
40
20
0
0
50
100
150
200
250
LOAD CURRENT (mA)
-80
0.01
0.1
1
FREQUENCY (kHz)
10
100
0
50
100
150
200
250
LOAD CURRENT (mA)
OUTPUT NOISE vs. FREQUENCY
MAX4834 toc07
SOFT-START RESPONSE
(C
SS
= FLOATING)
V
OUT
= 3.3V
50
V
IN
= 3V
V
OUT
= 1.8V
C
SS
= 10nF
I
LOAD
= 0
MAX4834 toc08
40
OUTPUT NOISE (µV
RMS
)
V
IN
2V/div
30
20
t
SS
V
OUT
2V/div
V
SS
1V/div
10
0
10
100
1k
FREQUENCY (Hz)
10k
100k
2ms/div
4
_______________________________________________________________________________________
250mA LDO Linear Regulators with
Current-Limiting Switch
Typical Operating Characteristics (continued)
(V
IN
= V
OUT
+ 1V,
SHDN
= IN, C
OUT
= 3.3µF, T
A
= +25°C, unless otherwise noted.)
MAX4834/MAX4835
SOFT-START RESPONSE
(C
SS
= 0.01µF)
MAX4834 toc09
SOFT-START RESPONSE
(C
SS
= 0.1µF)
MAX4834 toc10
LOAD-TRANSIENT RESPONSE
MAX4834 toc11
V
IN
2V/div
t
SS
t
SS
V
OUT
2V/div
V
IN
2V/div
V
IN
= 4.3V
V
OUT
= 3.3V
C
IN
= 0.1µF
C
OUT
= 3.3µF
I
LOAD
: STEP FROM 10mA TO 100mA
BACK TO 10mA
V
OUT
2V/div
V
OUT
50mV/div
AC-COUPLED
V
SS
1V/div
2ms/div
20ms/div
V
SS
1V/div
100µs/div
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
MAX4834 toc12
LINE-TRANSIENT RESPONSE
MAX4834 toc13
RESET RESPONSE TO V
IN
C
SS
= FLOATING
5V
V
IN
500mV/div
4.5V
V
OUT
50mV/div
AC-COUPLED
t
RESET
MAX4834 toc14
V
IN
= 3.4V
V
OUT
= 3.3V
C
IN
= 0.1µF
C
OUT
= 3.3µF
I
LOAD
: STEP FROM 10mA TO 100mA
BACK TO 10mA
V
IN
2V/div
V
OUT
50mV/div
AC-COUPLED
V
OUT
2V/div
C
IN
= 0.1µF
C
OUT
= 3.3µF
V
OUT
= 3.3V
I
LOAD
= 10mA
100µs/div
100µs/div
V
RESET
2V/div
40ms/div
RESET RESPONSE TO V
OUT
V
IN
= 3.5V, C
SS
= FLOATING
RESET RESPONSE TO SHUTDOWN
MAX4834 toc16
MAX4834 toc15
V
IN
= 3.5V, C
SS
= FLOATING
V
SHDN
2V/div
V
OUT
1V/div
V
OUT
2V/div
t
RESET
V
RESET
1V/div
t
RESET
V
RESET
2V/div
40ms/div
40ms/div
_______________________________________________________________________________________
5
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