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MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
General Description
The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches feature
internal current limiting to prevent damage to host devices
due to faulty load conditions. These analog switches feature a low 130mΩ (typ) on-resistance and operate from
a +1.7V to +5.5V input voltage range. The current limit is
adjustable from 50mA to 600mA, making these devices
ideal for SDIO (secure digital input/output) and other loadswitching applications.
Each device in the family handles an overcurrent
event differently depending on the option selected. The
MAX4995A/MAX4995AF/MAX4995AL go into an autoretry
mode, the MAX4995B latches off the switch, and the
MAX4995C places the device in a continuous current-limit
mode. Additional safety features include thermal shutdown
to prevent overheating and reverse-current blocking to
prevent current from being driven back into the source.
The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C are available in a tiny 10-pin, 1.4mm x 1.8mm
UTQFN, a 6-pin SOT23, or an 8-pin, 2mm x 2mm TDFN
package and operate over the -40°C to +125°C extended
temperature range.
Features
●● 50mA to 600mA Programmable Current Limit
●● ±10% Accurate Current Limit
●● Overload FLAG Threshold
●● Low Dropout Voltage
●● Short-Circuit Protection
●● Thermal Shutdown
●● Reverse-Current Protection
●● 170μA (typ) Supply Current
●● +1.7V to +5.5V Supply Voltage Range
●● Tiny 10-Pin, 1.4mm x 1.8mm UTQFN Package
Applications
●●
●●
●●
●●
SDIO Ports
USB Ports
Notebook VGA Ports
GPS
●● Cell Phones
●● MP3 Players
●● UTCA/ATCA Platforms
Typical Operating Circuit appears at end of data sheet.
Ordering Information/Selector Guide
PART
PIN-PACKAGE
ON POLARITY
OVERCURRENT
RESPONSE
SHORT-CIRCUIT
RESPONSE
TOP MARK
MAX4995AAUT+T*
6 SOT23
Active-High
Autoretry
Normal
+ACNZ
MAX4995AAVB+T
10 UTQFN
Active-High
Autoretry
Normal
+AAM
MAX4995AATA+T
8 TDFN-EP**
Active-High
Autoretry
Normal
+ABL
MAX4995AFAUT+T*
6 SOT23
Active-High
Autoretry
Fast
+ACOE
MAX4995AFAVB+T
10 UTQFN
Active-High
Autoretry
Fast
+AAR
MAX4995AFATA+T*
8 TDFN-EP**
Active-High
Autoretry
Fast
+ACO
MAX4995ALAUT+T*
6 SOT23
Active-Low
Autoretry
Normal
+ACOA
MAX4995ALAVB+T
10 UTQFN
Active-Low
Autoretry
Normal
+AAN
MAX4995ALATA+T*
8 TDFN-EP**
Active-Low
Autoretry
Normal
+ABM
MAX4995BAUT+T*
6 SOT23
Active-High
Latchoff
Normal
+ACOB
MAX4995BAVB+T
10 UTQFN
Active-High
Latchoff
Normal
+AAO
MAX4995BATA+T*
8 TDFN-EP**
Active-High
Latchoff
Normal
+ABN
MAX4995CAUT+T*
6 SOT23
Active-High
Continuous
Normal
+ACOD
MAX4995CAVB+T
10 UTQFN
Active-High
Continuous
Normal
+AAQ
MAX4995CATA+T*
8 TDFN-EP**
Active-High
Continuous
Normal
+ABP
All devices operate over the -40°C to +125°C temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*Future product. Contact factory for availability.
**EP = Exposed pad.
19-4363; Rev 3; 10/19
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Absolute Maximum Ratings
IN, ON, ON, FLAG, OUT, and SETI to GND............-0.3V to +6V
Current into Any Pin (Except IN, OUT)...............................20mA
OUT Short-Circuit to GND.................................................800mA
Continuous Power Dissipation (TA = +70°C) (Note 1)
10-Pin UTQFN (derate 6.99mW/°C above TA = +70°C)........ 559mW
6-Pin SOT23 (derate 13.4mW/°C above TA = +70°C)......1072.4mW
8-Pin TDFN (derate 11.9mW/°C above TA = +70°C)...........953.5mW
Junction-to-Ambient Thermal Resistance (θJA)
(Note 2)....................................................................143.1°C/W
Operating Temperature Range.......................... -40°C to +125°C
Storage Temperature Range............................. -65°C to +150°C
Junction Temperature.......................................................+150°C
Lead Temperature (soldering, 10s).................................. +300°C
Note 1: These power limits are defined by the thermal characteristics of the package, maximum function temperature (+150°C),
and the JEDEC51-7 defined setup. Maximum power dissipation could be lower, limited by the thermal-shutdown protection
included in this IC.
Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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.
Package Information
10 UTQFN
Package Code
V101A1CN+1
Outline Number
21-0028
6 SOT23
Package Code
U6SN+1
Outline Number
21-0058
8 TDFN
Package Code
T822+1
Outline Number
21-0168
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board.
For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
www.maximintegrated.com
Maxim Integrated │ 2
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Electrical Characteristics
(VIN = +1.7V to +5.5V, RSETI = 94.3kΩ, CIN = 1μF, and TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at
VIN = +3.3V, TA = +25°C.)
PARAMETER
SUPPLY OPERATION
Operating Voltage
Quiescent Current
SYMBOL
VIN
IQ
Latchoff Current
ILATCH
Shutdown Forward Current
ISHDN
Shutdown Reverse Current
IRSHDN
INTERNAL FET
Switch-On Resistance
Normalized Current-Limit
Accuracy
RON
CONDITIONS
VIN = 3.3V, IOUT lower than ILIM
ILIM = 50mA to 600mA, VIN - VOUT = 1V,
VIN = 3.3V (Note 3)
Reverse Blocking Current
VOUT > VIN + 300mV after reverse-current-limit
shutdown
Reverse Blocking Threshold
VOUT = VIN + 300mV, OUT falling until switch
turns on
FLAG Assertion Drop Voltage
Threshold
ON, ON INPUT
ON, ON Input Leakage
ON, ON Input Logic-High Voltage
ON, ON Input Logic-Low Voltage
FLAG OUTPUT
FLAG Output Logic-Low Voltage
FLAG Output Leakage Current
DYNAMIC
VFA
ILEAK
VIH
VIL
TYP
MAX
UNITS
170
5.5
300
V
µA
8
15
µA
0.01
5
µA
0.01
1
µA
130
350
mΩ
1
1.1
—
31946
V
10
µA
210
mV
1.7
IOUT = 0, switch on, VIN = 3.3V
VIN = 3.3V, IOUT = 0 after an overcurrent fault
(MAX4995B)
VON = 0, VON = VIN, VIN = 5.5V, VOUT = 0
VON = 0, VON = VIN, VIN = 1.7V,
VOUT = 5.5V (current into OUT)
ILIM = 50mA to 600mA, VIN - VOUT = 1V,
VIN = 3.3V
(RSETI + 2.48) x ILIM Product
MIN
0.9
26138 29042
35
Increase (VIN - VOUT) drop until FLAG asserts,
IOUT limiting, VIN = 3.3V
VON, VON = VIN or GND
110
650
-1
1.6
mV
+1
ISINK = 1mA
VIN = VFLAG = 5.5V, FLAG deasserted
0.4
µA
V
V
0.4
1
V
µA
Turn-On Time
tSS
VIN = 3.3V, COUT = 1µF, RL = 20Ω, Figure 1,
(Note 4)
120
µs
Turn-Off Time
tOFF
Switch from on to off, VIN = 3.3V, COUT = 1µF,
RL = 20Ω, Figure 1 (Note 4)
120
µs
Current-Limit Reaction Time
tLIM
VIN = 3.3V, RSETI =
578kΩ, output high and
then short-circuit applied
Blanking Time
Retry Time
THERMAL PROTECTION
Thermal Shutdown
Thermal-Shutdown Hysteresis
www.maximintegrated.com
tBLANK
tRETRY
MAX4995A/AL/B/C
5
MAX4995AF
(Note 5)
MAX4995A/MAX4995AF/MAX4995AL (Note 5)
µs
1.5
10
320
16.3
+150
15
22.6
723.2
ms
ms
°C
°C
Maxim Integrated │ 3
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Electrical Characteristics (continued)
(VIN = +1.7V to +5.5V, RSETI = 94.3kΩ, CIN = 1μF, and TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at
VIN = +3.3V, TA = +25°C.)
Note 3: ILIM is forward current limit.
I LIM(mA) =
29042(V)
R SETI(kΩ ) + 2.48(kΩ )
Note 4: Turn-on time and turn-off time are defined as the difference in the time between when the output crosses 10% and 90% of
the final output voltage.
Note 5: Blanking time and retry time are generated by the same oscillator. Therefore, the ratio of
t RETRY
t BLANK
is a constant value of 32. See Figure 2 and 3.
tSS
90%
90%
VOUT
10%
10%
tOFF
Figure 1. Timing Diagram for Measuring Turn-On Time (tSS) and Turn-Off Time (tOFF).
www.maximintegrated.com
Maxim Integrated │ 4
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Typical Operating Characteristics
(VIN = +3.3V, CIN = 1μF, COUT = 1μF, RSETI = 94.2kΩ, TA = +25°C, unless otherwise noted.)
CURRENT LIMIT (mA)
310
305
300
295
290
285
1.100
1.075
NORMALIZED CURRENT LIMIT
vs. TEMPERATURE
MAX4995A toc02
MAX4995AL
NORMALIZED CURRENT LIMIT
MAX4995A toc01
315
CURRENT LIMIT
vs. SUPPLY VOLTAGE
MAX4995AL
1.050
1.025
1.000
0.975
0.950
0.925
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0.900
5.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
CURRENT-LIMIT RESPONSE (MAX4995AF)
CURRENT-LIMIT RESPONSE (MAX4995A)
MAX4995A toc04
MAX4995A toc03
SUDDEN SHORT
APPLIED AT OUTPUT
SUDDEN SHORT
APPLIED AT OUTPUT
VOUT
(2V/div)
VOUT
(2V/div)
IOUT
(10A/div)
IOUT
(10A/div)
10µs/div
CURRENT-LIMIT RESPONSE
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4995A toc05
VOUT
(2V/div)
IOUT
(100mA/div)
4ms/div
QUIESCENT SUPPLY CURRENT (A)
300
RLOAD = 8Ω
280
MAX4995A toc06
10µs/div
MAX4995A
260
240
220
200
180
160
140
120
100
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
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Maxim Integrated │ 5
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Typical Operating Characteristics (continued)
VIN = 3.3V
0.25
20
VIN = 1.7V
10
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
MAX4995A toc09
MAX4995A toc08
0.50
30
-40 -25 -10 5 20 35 50 65 80 95 110 125
MAX4995C
VOUT = 5.5V
VIN = 5V
50
VIN = 1.7V
20
18
MAX4995B
VIN = 5V
16
14
VIN = 3.3V
12
10
8
25
6
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
1.040
MAX4995A toc12
NORMALIZED ON-RESISTANCE
vs. SUPPLY VOLTAGE
MAX4995A toc11
LATCHOFF CURRENT
vs. TEMPERATURE
75
MAX4995C
IOUT < ILIM
1.035
1.030
1.025
1.020
1.015
1.010
1.005
1.000
0.995
0.990
0.985
0.980
1.7
2.2
2.7
3.2
3.7
4.2
4.7
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
SWITCH TURN-ON TIME
vs. TEMPERATURE
SWITCH TURN-OFF TIME
vs. TEMPERATURE
1.1
1.0
0.9
0.8
0.7
180
170
MAX4995C
ILOAD = 10mA
160
150
140
VIN = 5V
130
120
VIN = 3.3V
110
0.6
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
www.maximintegrated.com
100
1.6
1.5
SWITCH TURN-OFF TIME (ms)
MAX4995C
VIN = 3.3V
1.4
1.3
5.2
MAX4995A toc15
TEMPERATURE (°C)
1.2
0.5
0.75
VIN = 5V
40
SHUTDOWN REVERSE CURRENT
vs. TEMPERATURE
100
1.3
VIN = 5V
1.00
50
TEMPERATURE (°C)
125
1.4
1.25
60
TEMPERATURE (°C)
150
1.5
1.50
MAX4995C
70
TEMPERATURE (°C)
175
0
1.75
SHUTDOWN FORWARD CURRENT
vs. TEMPERATURE
80
NORMALIZED ON-RESISTANCE
200
2.00
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
SWITCH TURN-ON TIME (s)
SHUTDOWN REVERSE CURRENT (nA)
225
MAX4995AL
MAX4995AL
MAX4995A toc14
170
160
VIN = 3.3V
MAX4995A toc10
180
2.25
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN FORWARD CURRENT (nA)
210
200
190
2.50
SHUTDOWN SUPPLY CURRENT (A)
230
220
150
140
NORMALIZED ON-RESISTANCE
VIN = 5V
LATCHOFF CURRENT (A)
240
MAX4995A toc07
260
250
QUIESCENT SUPPLY LIMIT
vs. TEMPERATURE
MAX4995A toc13
QUIESCENT SUPPLY CURRENT (A)
(VIN = +3.3V, CIN = 1μF, COUT = 1μF, RSETI = 94.2kΩ, TA = +25°C, unless otherwise noted.)
MAX4995C
ILOAD = 10mA
VIN = 5V
1.2
1.1
1.0
0.9
0.8
VIN = 3.3V
0.7
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
0.6
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
Maxim Integrated │ 6
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Typical Operating Characteristics (continued)
(VIN = +3.3V, CIN = 1μF, COUT = 1μF, RSETI = 94.2kΩ, TA = +25°C, unless otherwise noted.)
SWITCH TURN-OFF TIME RESPONSE
SWITCH TURN-ON TIME RESPONSE
MAX4995A toc17
MAX4995A toc16
VON
(5V/div)
VON
(5V/div)
VOUT
(2V/div)
VOUT
(2V/div)
200µs/div
200µs/div
MAX4995A toc18
SWITCH DROPOUT VOLTAGE (mV)
19
IOUT
(200mA/div)
VOUT
(2V/div)
VFLAG
(2V/div)
MAX4995A toc19
SWITCH DROPOUT VOLTAGE
vs. TEMPERATURE
FLAG RESPONSE (OVERLOAD) CONDITION
MAX4995A
ILOAD = 100mA
18
17
16
15
14
13
12
11
10
9
100ms/div
VIN = 3.3V
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAX4995B
1
FLAG (LOGIC-LEVEL STATUS)
300
MAX4995A toc20
IOUT/FLAG vs. VDROP (VIN - VOUT)
350
IOUT (mA)
250
200
150
100
50
0
VIN = 5.5V
0
0
70 140 210 280 350 420 490 560 630 700
VDROP (mV)
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Maxim Integrated │ 7
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Pin Configurations
TOP VIEWS
IN
FLAG
IN
N.C.
OUT
OUT
N.C.
SETI
GND
10
9
8
8
7
6
5
7
1
2
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
3
4
6
OUT
1
GND
2
SETI
3
OUT
N.C.
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
6
FLAG
5
IN
4
ON (ON)*
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
5
SOT23
(1.6mm x 2.9mm)
ON (ON)*GND SETI
UTQFN
(1.4mm x 1.8mm)
*EP
+
1
2
3
IN
IN
FLAG
4
ON (ON)*
TDFN
(2mm x 2mm)
*( ) FOR THE MAX4995AL ONLY.
**EXPOSED PAD. CONNECT EP TO GND.
Pin Description
PIN (UTQFN)
MAX4995AL
1, 10
PIN (TDFN-EP)
MAX4995_
1, 10
MAX4995AL
1, 2
MAX4995_
1, 2
PIN (SOT23)
MAX4995AL
5
MAX4995_
5
NAME
FUNCTION
IN
Power Input. Bypass IN with a
1µF ceramic capacitor to ground.
Use higher capacitance to
prevent large load transients from
pulling down the supply voltage if
necessary. Connect both power
inputs (IN) together.
Open-Drain, Overload Indicator
Output. FLAG goes low when the
overload fault duration exceeds
FLAG the blanking time, reverse current
is detected, thermal shutdown
mode is active, or SETI is
connected to ground.
2
2
3
3
6
6
3
—
4
—
4
—
ON
Active-Low, Switch-On Input. Drive
ON low to turn on the switch.
—
3
—
4
—
4
ON
Active-High, Switch-On Input.
Drive ON high to turn on the switch.
4
4
5
5
2
2
GND
Ground
SETI
Overload Current Limit Adjust.
Connect a resistor from SETI to
ground to program the overcurrent
limit. Do not connect any
capacitance larger than 20pF to
SETI.
5
5
www.maximintegrated.com
6
6
3
3
Maxim Integrated │ 8
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Pin Description (continued)
PIN (UTQFN)
PIN (TDFN-EP)
PIN (SOT23)
NAME
FUNCTION
MAX4995AL
MAX4995_
MAX4995AL
MAX4995_
MAX4995AL
MAX4995_
6, 9
6, 9
7
7
—
—
N.C.
No Connect. Not internally
connected.
7, 8
7, 8
8
8
1
1
OUT
Switch Output. Bypass OUT with a
1µF capacitor to ground. Connect
both outputs (OUT) together.
—
—
—
—
—
—
EP
Exposed Pad. Connect EP to
GND. For TDFN package only.
Functional Diagram
MAX4995A/MAX4995AF/
MAX4995AL/MAX4995B/
MAX4995C
REVERSECURRENT
PROTECTION
IN
OUT
THERMAL
SHUTDOWN
UVLO
CONTROL
LOGIC
BUFFER
FLAG
TIMING
CIRCUITRY
BANDGAP
REFERENCE
N.C.
SOFT-START
CURRENT
LIMIT
SETI
BUFFER
ON (ON)*
GND
*( ) FOR THE MAX4995AL ONLY.
www.maximintegrated.com
Maxim Integrated │ 9
MAX4995A/AF/AL/
MAX4995B/MAX4995C
Detailed Description
The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches operate
from +1.7V to +5.5V and provide internal current limiting
adjustable from 50mA to 600mA. These devices feature
a fixed blanking time and a FLAG output that notifies the
processor when a fault condition is present.
Programmable Current Limit
A resistor from SETI to GND programs the current limit for
the switch (see the Setting the Current Limit section). If the
output current exceeds the current limit for a time equal
to or longer than tBLANK, the output flag asserts and the
MAX4995A/MAX4995AF/MAX4995AL enter the autoretry
mode. The MAX4995B latches off the switch, and the
MAX4995C enters the continuous current-limit mode.
Autoretry (MAX4995A/MAX4995AF/
MAX4995AL)
When the forward current reaches the current-limit threshold, the tBLANK timer begins counting (Figure 2). FLAG
asserts if the overcurrent-limit condition is present for
tBLANK. The timer resets if the overcurrent condition
disappears before the blanking time (tBLANK) has elapsed.
A retry time delay (tRETRY) starts immediately after the
blanking time has elapsed and during that time, the switch
latches off. At the end of tRETRY, the switch turns on
again. If the fault still exists, the cycle repeats. If the fault
has been removed, the switch stays on. During this cycle,
FLAG stays low. In autoretry if the thermal power rating of
the package is exceeded, the MAX4995A/MAX4995AF/
MAX4995AL go into thermal shutdown.
The autoretry feature saves system power in case of an
overcurrent or short-circuit condition. During tBLANK time
when the switch is on, the supply current is held at the
current limit. During time tRETRY when the switch is off,
the current through the switch is zero. Thus, the average
output current is much less than the programmed current
limit. Calculate the average output current using the following equation:
ILOAD = ILIM [tBLANK/(tBLANK + tRETRY)]
With a typical tBLANK = 16.3ms and typical tRETRY =
524ms, the duty cycle is 3%, resulting in a 97% power
savings over the switch being on the entire time.
www.maximintegrated.com
50mA to 600mA Programmable
Current-Limit Switches
Table 1. Switch Truth Table
MAX4995_/
MAX4995AF
MAX4995AL
SWITCH
STATUS
ON
ON
0
1
Off
1
0
On
Latchoff (MAX4995B)
When the forward current reaches the current-limit
threshold, the tBLANK timer begins counting (Figure 3).
FLAG asserts if an overcurrent-limit condition is present
for greater than tBLANK time. The timer resets if the overcurrent condition disappears before tBLANK has elapsed.
The switch turns off if the overcurrent condition continues
beyond the blanking time. Reset the switch by either toggling the control logic (ON) or cycling the input voltage. If
the thermal power rating of the package is exceeded during tBLANK, the MAX4995B goes into thermal shutdown.
Continuous Current Limit (MAX4995C)
When the forward current reaches the forward currentlimit
threshold, the MAX4995C limits the output current to the
programmed current limit. FLAG asserts if the current limit
is present for tBLANK and deasserts when the overload
condition is removed. In this mode, if the thermal power
rating of the package is exceeded, the MAX4995C goes
into thermal shutdown.
Switch-On/Off Control
The ON input for the MAX4995_/MAX4995AF and ON
input for the MAX4995AL control the switch; see Table 1.
Toggle ON for the MAX4995B to reset the fault condition
once the short current is detected and the device shuts
down.
Reverse-Current Protection
The MAX4995 features a reverse-current protection
circuit that limits the backflow current to 10μA when the
output voltage exceeds the input voltage by 110mV (typ).
The switch turns off and FLAG asserts without waiting for
tBLANK to elapse. The switch turns back on and FLAG
deasserts when the output voltage drops below the
detecting threshold by 10mV (typ).
Maxim Integrated │ 10
MAX4995A/AF/AL/
MAX4995B/MAX4995C
tBLANK
50mA to 600mA Programmable
Current-Limit Switches
tRETRY
tBLANK
tRETRY
tBLANK
tBLANK
OUT
CURRENT LIMIT
THE DEVICE GOES TO
THERMAL-SHUTDOWN MODE
LOAD CURRENT
FLAG
Figure 2. Autoretry Fault Diagram
tBLANK
tBLANK
OUT
CURRENT LIMIT
LOAD CURRENT
THE DEVICE GOES TO
THERMAL-SHUTDOWN MODE
FLAG
Figure 3. Latchoff Fault Diagram
FLAG Indicator
FLAG is an open-drain fault indicator output and requires
an external pullup resistor to a DC supply. FLAG goes low
when any of the following conditions occurs:
● The device is in current-limit mode.
● The OUT voltage is above the IN voltage by more than
110mV (typ).
Thermal Shutdown
Thermal-shutdown circuitry protects the devices from
overheating. The switch turns off and FLAG goes low
immediately when the junction temperature exceeds
+150°C (typ). The switch turns on again after the device
temperature drops by approximately 15°C (typ).
● The die temperature exceeds the thermal-shutdown
temperature limit of +150°C.
● SETI is connected to ground.
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Maxim Integrated │ 11
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Applications Information
Output Capacitor
Setting the Current Limit
A resistor from SETI to ground programs the current-limit
value for the MAX4995. Table 2 lists various current limits
set by different resistor values at SETI. Shorting SETI to
ground asserts FLAG.
Use the following formula to calculate the current limit:
=
R SETI(kΩ )
29042(V)
− 2.48(kΩ)
I LIM (mA)
Using an RSETI with a value smaller than 45.8kΩ results
in a higher current limit. A programmed output current
greater than 660mA can damage the device.
Connecting any capacitance larger than 20pF to SETI can
cause instability.
Table 2. Current Limit vs. Resistor Values
RSETI (kΩ)
45.8
TYPICAL CURRENT LIMIT (mA)
55.6
500
70.6
397
94.2
300
143
200
191
150
287
100
576
50
∞ (Open)
0
602
Input Capacitor
Connect a capacitor from IN to GND to limit the input
voltage drop during momentary output short-circuit
conditions. Use a 1μF minimum ceramic capacitor for
proper device operation. Larger capacitor values reduce
the voltage undershoot at the input.
Due to the very fast current-limit reaction time of the
MAX4995AF, a larger input capacitance might need to be
connected at the input to dampen oscillation due to long
wires. Choose a value large enough to ensure IN doesn’t
exceed the absolute maximum ratings.
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For stable operation over the full temperature range and
over the full programmable current-limit range, use a 1μF
ceramic capacitor from OUT to ground.
If the load capacitance is too large, then current may
not have enough time to charge the capacitance and
the device assumes that there is a faulty load condition.
Calculate the maximum capacitive load (CMAX) value that
can be connected to OUT using the following formula:
C MAX (µF) =
I LIM(mA) × t BLANK(MIN) (ms)
VIN (V )
For example, for VIN = 3.3V, tBLANK(MIN) = 10ms, and
ILIM = 300mA, CMAX equals 909μF.
Due to the very fast current-limit reaction time of the
MAX4995AF, a larger output capacitance might need to
be connected at the output to dampen oscillation due to
long wires. Choose a value large enough to ensure OUT
doesn’t exceed the absolute maximum ratings.
Layout and Thermal Dissipation
To optimize the switch response time to output shortcircuit conditions, it is very important to keep all traces
as short as possible to reduce the effect of undesirable
parasitic inductance. Place input and output capacitors
as close as possible to the device. IN and OUT must be
connected with wide, short traces to the power bus. During
normal operation, the power dissipation is small and the
package temperature change is minimal. If the output is
continuously shorted to ground at the maximum supply
voltage, the operation of the switches with the autoretry
option does not cause problems because the total power
dissipated during the short is scaled by the duty cycle:
PMAX =
VIN(MAX) × I OUT(MAX) × t BLANK
t RETRY + t BLANK
Attention must be given to the MAX4995C continuous
current-limit version when the power dissipation during
a fault condition may cause the device to reach thermal
shutdown threshold.
Maxim Integrated │ 12
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Typical Operating Circuit
VCC
1µF
VIO
IN
FLAG
ON
(ON*)
µP
MAX4995A/
MAX4995AF/
MAX4995AL/
MAX4995B/
MAX4995C
SETI
RSETI
OUT
1µF
LOAD
N.C.
GND
*( ) FOR THE MAX4995AL ONLY.
Chip Information
PROCESS: BiCMOS
www.maximintegrated.com
Maxim Integrated │ 13
MAX4995A/AF/AL/
MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
1/15
Initial release.
1
6/09
Corrected the Ordering Information/Selector Guide.
2
2/10
Added TDFN package information to the Ordering Information/Selector Guide, Absolute
Maximum Ratings, Pin Description, and Package Information sections, added the TDFN
pin configuration drawing to the Pin Configurations section.
3
10/19
Updated the Ordering Information/Selector Guide.
DESCRIPTION
—
1, 11
1, 2, 7, 12
1
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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