MAX4835ETT28BD4+T [MAXIM]
Fixed Positive LDO Regulator, 2.8V, 0.165V Dropout, BICMOS, PDSO6, 3 X 3 MM, ROHS COMPLIANT, TDFN-6;
| 型号： | MAX4835ETT28BD4+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Fixed Positive LDO Regulator, 2.8V, 0.165V Dropout, BICMOS, PDSO6, 3 X 3 MM, ROHS COMPLIANT, TDFN-6 信息通信管理 光电二极管 输出元件 调节器 |
| 文件： | 总11页 (文件大小：234K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3373; Rev 1; 8/11
250mA LDO Linear Regulators with
Current-Limiting Switch
/MAX4835
General Description
Features
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.
o Guaranteed Minimum 250mA Load Current
o Accurate Current Limit
o Preset Output Voltages: 1.8V/2.5V/2.8V/3.0V/3.3V
o 2.5V to 5.5V Supply Voltage Range
o Adjustable Soft-Start
o Low Dropout Voltage
o Thermal Shutdown
o Reverse-Current Protection
o Shutdown Output Discharge (MAX4835)
o Low 90µA Supply Current
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.
o Ultra-Low 0.1µA Shutdown 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.
o FLAG and Latch Off (MAX4834) or RESET
(MAX4835)
o 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 500mA
versions of this device, refer to the MAX4836/MAX4837.
PART
TEMP RANGE PIN-PACKAGE
-40°C to +85°C 6 SOT23
MAX4834EUTxy_+T*
MAX4834ETTxy_+T
MAX4835EUTxy_dd+T*
MAX4835ETTxy_dd+T
Applications
-40°C to +85°C 6 TDFN-EP*
-40°C to +85°C 6 SOT23
SDIO Ports and Devices
USB Ports and Devices
Notebook Computers
Cell Phones
-40°C to +85°C 6 TDFN-EP*
PDAs and Palmtop Devices GPS Systems
MAX4835ETT18BD2/V+T -40°C to +85°C 6 TDFN-EP*
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.
Pin Configurations
TOP VIEW
+
1
IN
OUT
SS
6
5
4
2
3
GND
MAX4834/MAX4835
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
RESET
(FLAG)
SHDN
EXPOSED PADDLE
*EP = Exposed pad.
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 Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
250mA LDO Linear Regulators with
Current-Limiting Switch
ABSOLUTE MAXIMUM RATINGS
Continuous Power Dissipation (T = +70°C)
6-Pin SOT23 (derate 9.1mW/°C above +70°C)................727mW
IN, SHDN, FLAG, OUT to GND ................................-0.3V to +6V
A
RESET to GND .........................................-0.3V to (V
+ 0.3V)
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
Soldering Temperature (reflow) .......................................+260°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
= 3.3µF, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
OUT A A
(V = V
+ 1V, SHDN = IN, C
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
/MAX4835
Input Undervoltage Lockout
Threshold Hysteresis
50
90
mV
SHDN = IN, I
SHDN = IN, I
= 0A
150
OUT
= 0A,
(nominal)
OUT
OUT
150
Quiescent Current
I
µA
Q
V
< V < V
UVLO
IN
SHDN = GND, I
= 0A
0.1
2
OUT
T
T
= +25°C
103
140
165
+1.3
+2
A
A
Dropout Voltage (Note 2)
Output Voltage Accuracy
I
= 250mA
mV
OUT
= -40°C to +85°C
I
I
= 1mA to 250mA, T = +25°C
-1.3
-2
OUT
A
%V
NOM
= 1mA to 250mA, T = -40°C to +85°C
OUT
A
Output Current
I
250
270
mA
OUT
Output Current Limit
V
V
= 0V
330
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
-0.05
+0.02 +0.065
%V
V
+ 0.5V < V
LOAD
<
A
/
OUT
IN
NOM
V
5.5V, I
= 100µA
= -40°C to +85°C
+0.03
1.3
+0.08
A
Load Regulation
100µA < I
< 250mA, V = V
+ 1V
%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 (MAX4835)
SHDN = GND
900
30
Ω
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
_______________________________________________________________________________________
250mA LDO Linear Regulators with
Current-Limiting Switch
/MAX4835
ELECTRICAL CHARACTERISTICS (continued)
= 3.3µF, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
OUT A A
(V = V
+ 1V, SHDN = IN, C
IN
OUT
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
RESET OUTPUT (MAX4835)
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 (MAX4834)
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
OUT
measured from V
to GND when V is 1V greater than V
. Defined only for V
≥ 2.5V.
OUT
IN
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
250mA 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)
QUIESCENT CURRENT vs. INPUT VOLTAGE
(250mA LOAD)
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
120
100
80
60
40
20
0
500
90
75
60
45
30
15
0
T
= +85°C
A
T
A
= +85°C
400
300
200
100
0
RESET ASSERTS
ABOVE THIS LINE
T
A
= +25°C
T
= +25°C
A
T
A
= -40°C
T
A
= -40°C
V
OUT
= 3.5V
= 2.5V
IN
V
= 1.5V
V
OUT
= 3.3V
OUT
V
0
1
2
3
4
5
6
0
1
2
3
4
5
6
1
10
RESET THRESHOLD OVERDRIVE (mV)
100
/MAX4835
V
(V)
V (V)
IN
IN
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
REGION OF STABLE C
ESR
OUT
DROPOUT VOLTAGE vs. LOAD CURRENT
vs. LOAD CURRENT
0
7
6
5
4
3
2
1
0
100
80
60
40
20
0
V
= 1.8V
OUT
V
= 3.3V
V
= 2V
OUT
OUT
-10
-20
-30
-40
-50
-60
-70
-80
C
= 3.3µF
= 20mA
OUT
I
LOAD
C
= 3.3µF
OUT
STABLE REGION
0.01
0.1
1
10
100
0
50
100
150
200
250
0
50
100
150
200
250
FREQUENCY (kHz)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
SOFT-START RESPONSE
(C = UNCONNECTED)
OUTPUT NOISE vs. FREQUENCY
SS
= 3.3V
MAX4834 toc08
50
40
30
20
10
V
OUT
V
V
C
= 3V
IN
= 1.8V
= 10nF
OUT
SS
V
IN
I
= 0
LOAD
2V/div
V
t
SS
OUT
2V/div
V
SS
1V/div
0
10
100
1k
10k
100k
2ms/div
FREQUENCY (Hz)
4
_______________________________________________________________________________________
250mA LDO Linear Regulators with
Current-Limiting Switch
/MAX4835
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
(C = 0.01µF)
(C = 0.1µF)
LOAD-TRANSIENT RESPONSE
MAX4834 toc11
SS
SS
MAX4834 toc09
MAX4834 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
t
SS
V
OUT
V
OUT
50mV/div
AC-COUPLED
2V/div
V
t
SS
OUT
2V/div
V
SS
V
SS
1V/div
1V/div
2ms/div
20ms/div
100µs/div
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
RESET RESPONSE TO V
LINE-TRANSIENT RESPONSE
IN
MAX4834 toc12
MAX4834 toc13
MAX4834 toc14
V
V
C
C
= 3.4V
C
SS
= UNCONNECTED
IN
= 3.3V
= 0.1µF
= 3.3µF
OUT
IN
V
5V
IN
OUT
2V/div
V
IN
I
: STEP FROM 10mA TO 100mA
LOAD
500mV/div
4.5V
BACK TO 10mA
V
OUT
50mV/div
AC-COUPLED
V
OUT
V
OUT
2V/div
50mV/div
AC-COUPLED
C
C
V
= 0.1µF
= 3.3µF
IN
OUT
V
RESET
= 3.3V
t
OUT
RESET
2V/div
I
= 10mA
LOAD
100µs/div
40ms/div
100µs/div
RESET RESPONSE TO SHUTDOWN
RESET RESPONSE TO V
OUT
MAX4834 toc16
MAX4834 toc15
V
IN
= 3.5V, C = UNCONNECTED
SS
V
= 3.5V, C = UNCONNECTED
IN
SS
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
250mA 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)
MAX4834 toc17
MAX4834 toc18
MAX4834 toc19
V
V
V
OUT
OUT
OUT
1V/div
1V/div
1V/div
t
BLANK
V
V
FLAG
2V/div
FLAG
t
BLANK
2V/div
I
OUT
200mA/div
V
FLAG
V
V
SHDN
2V/div
IN
2V/div
2V/div
FLAG CONNECTED TO LOGIC SUPPLY
10ms/div
FLAG CONNECTED TO LOGIC SUPPLY
10ms/div
/MAX4835
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
MAX4834 toc20
MAX4834 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
V
V
I
= 250mA
OUT
OUT
LOAD
t
t
BLANK
BLANK
2V/div
2V/div
t
SS
t
SS
I
= 10mA
LOAD
V
V
FLAG
FLAG
I = 100mA
LOAD
2V/div
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
OUT
= 2.5V
V
I
= 2.5V
OUT
TEMPERATURE (°C)
I
= I
LOAD LIMIT
FLAG CONNECTED TO LOGIC SUPPLY
FLAG CONNECTED TO LOGIC SUPPLY
6
_______________________________________________________________________________________
250mA LDO Linear Regulators with
Current-Limiting Switch
/MAX4835
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
(MAX4834)
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
(MAX4835)
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 0.2Ω for stable operation.
6
6
OUT
EP
Exposed Pad (TDFN only). 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.
—
—
RESET Output (MAX4835)
Detailed Description
The RESET output asserts when one of the following
The MAX4834/MAX4835 are ultra-low quiescent current,
low-dropout linear regulators with an integrated current
limiter. These devices guarantee up to 250mA 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 MAX4834 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 MAX4835 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 (MAX4834)
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
250mA LDO Linear Regulators with
Current-Limiting Switch
THERMAL
PROTECTION
MAX4834/MAX4835
PASS
TRANSISTOR
REVERSE-
CURRENT
IN
OUT
PROTECTION
ERROR
AMPLIFIER
MAX4835 ONLY
V
SS
900Ω
v
FB
SWITCH
CLOSED IN
SHUTDOWN
OVERLOAD
PROTECTION
V
REF
1.23V
V
REF
SHDN
/MAX4835
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
( ) MAX4834E_ _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
V
2.5V TO 5.5V
LOGIC
LOAD
LOAD
MAX4834
MAX4835
SS
SS
TO µC
FLAG
TO µC
RESET
SHDN
C
SS
C
SS
ON
ON
SHDN
GND
GND
OFF
OFF
Figure 2. Typical Application Circuits
_______________________________________________________________________________________
8
250mA LDO Linear Regulators with
Current-Limiting Switch
/MAX4835
Shutdown Discharge (MAX4835)
Applications Information
Capacitor Selection and Regulator
Stability
OUT discharges through a 900Ω internal 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 250mA, use a 3.3µF (min)
ceramic output capacitor with an ESR <0.2Ω. 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 MAX4834/MAX4835 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 MAX4834/MAX4835 remain stable with purely
resistive loads or current loads up to 250mA.
The MAX4834 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 MAX4835 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 0.2Ω.
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
Characteristics show a graph of the Maximum Transient
Duration vs. Reset Threshold Overdrive for which reset is
OUT
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
Operating Characteristics. The soft-start time (t ) is
SS
given by the following equation:
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
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.
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
250mA LDO Linear Regulators with
Current-Limiting Switch
Selector Guide
PIN-
OUTPUT
RESET OUTPUT
SHUTDOWN
LATCH OFF
DISCHARGE
PART
RESET (FLAG)
PACKAGE CURRENT (mA) CONFIGURATION
MAX4834EUTxyC+T
MAX4834ETTxyC+T
6 SOT23
6 TDFN
6 SOT23
6 TDFN
6 TDFN
250
250
250
250
250
Open-Drain
Open-Drain
Push-Pull
FLAG
FLAG
No
No
Yes
Yes
No
MAX4835EUTxyBdd+T
MAX4835ETTxyBdd+T
MAX4835ETT18BD2/V+T
RESET
RESET
RESET
Yes
Yes
Yes
Push-Pull
No
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)
/MAX4835
+
1.8
2.5
2.8
3.0
3.3
IN
GND
1
2
3
6
5
4
OUT
SS
MAX4834/
MAX4835
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
( ) MAX4834EUTxyC ONLY.
dd
D1
D2
D3
D4
RESET TIMEOUT (ms)
Chip Information
3.75
30
PROCESS: BiCMOS
225
1800
TDFN Exposed Pad: Connected to GND
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
LAND
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE NO.
PATTERN NO.
90-0175
90-0058
6 SOT23
U6F+6
21-0058
21-0137
6 TDFN
T633+2
10 ______________________________________________________________________________________
250mA LDO Linear Regulators with
Current-Limiting Switch
/MAX4835
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
DESCRIPTION
CHANGED
0
7/04
Initial release
—
Added MAX4835ETT18BD2/V+T and lead-free versions of all parts to the
Ordering Information and Selector Guide
1
8/11
1, 10
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11
© 2011 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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