General Description
The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches fea-
ture 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/out-
put) and other load-switching 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
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
________________________________________________________________
Maxim Integrated Products
1
Ordering Information/Selector Guide
19-4363; Rev 2; 2/10
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.
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.
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 +ACDA
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 +ACDB
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
Typical Operating Circuit appears at end of data sheet.
SDIO Ports
USB Ports
Notebook VGA Ports
GPS
Cell Phones
MP3 Players
UTCA/ATCA Platforms
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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, 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.maxim-ic.com/thermal-tutorial.
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 SYMBOL CONDITIONS MIN TYP MAX UNITS
SUPPLY OPERATION
Operating Voltage VIN 1.7 5.5 V
Quiescent Current IQ I
OUT = 0, switch on, VIN = 3.3V 170 300 μA
Latchoff Current ILATCH VIN = 3.3V, IOUT = 0 after an overcurrent
fault (MAX4995B) 8 15 μA
Shutdown Forward Current ISHDN VON = 0, VON = VIN, VIN = 5.5V, VOUT = 0 0.01 5 μA
Shutdown Reverse Current IRSHDN VON = 0, VON = VIN, VIN = 1.7V,
VOUT = 5.5V (current into OUT) 0.01 1 μA
INTERNAL FET
Switch-On Resistance RON VIN = 3.3V, IOUT lower than ILIM 130 350 m
Normalized Current-Limit Accuracy ILIM = 50mA to 600mA, VIN - VOUT = 1V,
VIN = 3.3V (Note 3) 0.9 1 1.1 —
(RSETI + 2.48) x ILIM Product
ILIM = 50mA to 600mA, VIN - VOUT = 1V,
VIN = 3.3V 26138 29042 31946 V
Reverse Blocking Current VOUT > VIN + 300mV after reverse-current-
limit shutdown 10 μA
Reverse Blocking Threshold VOUT = VIN + 300mV, OUT falling until switch
turns on 35 110 210 mV
FLAG Assertion Drop Voltage
Threshold VFA Increase (VIN - VOUT) drop until FLAG
asserts, IOUT limiting, VIN = 3.3V 650 mV
ON, ON INPUT
ON, ON Input Leakage ILEAK V
ON, VON = VIN or GND -1 +1 μA
ON, ON Input Logic-High Voltage VIH 1.6 V
ON, ON Input Logic-Low Voltage VIL 0.4 V
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
_______________________________________________________________________________________ 3
Note 3: ILIM is forward current limit.
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
is a constant value of 32. See Figures 2 and 3.
t
t
RETRY
BLANK
I (mA) 2
R(k 2.48k
LIM SETI
=+
9042( )
)()
V
ΩΩ
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.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FLAG OUTPUT
FLAG Output Logic-Low Voltage ISINK = 1mA 0.4 V
FLAG Output Leakage Current VIN = VFLAG = 5.5V, FLAG deasserted 1 μA
DYNAMIC
Turn-On Time tSS VIN = 3.3V, COUT = 1μF, RL = 20 , Figure 1,
(Note 4) 120 μs
Turn-Off Time tOFF Switch from on to off, VIN = 3.3V, COUT = 1μF,
RL = 20 , Figure 1 (Note 4) 120 μs
MAX4995A/AL/B/C 5
Current-Limit Reaction Time tLIM
VIN = 3.3V, RSETI =
578k , output high and
then short-circuit
applied MAX4995AF 1.5
μs
Blanking Time tBLANK (Note 5) 10 16.3 22.6 ms
Retry Time tRETRY MAX4995A/MAX4995AF/MAX4995AL (Note 5) 320 723.2 ms
THERMAL PROTECTION
Thermal Shutdown +150 °C
Thermal-Shutdown Hysteresis 15 °C
tSS
10%
90%
10%
90%
tOFF
VOUT
Figure 1. Timing Diagram for Measuring Turn-On Time (tSS) and Turn-Off Time (tOFF).
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
4 _______________________________________________________________________________________
CURRENT LIMIT
vs. SUPPLY VOLTAGE
MAX4995A toc01
SUPPLY VOLTAGE (V)
CURRENT LIMIT (mA)
2.0 3.02.5 4.5 5.03.5 4.0
290
295
300
305
310
315
285
1.5 5.5
MAX4995AL
NORMALIZED CURRENT LIMIT
vs. TEMPERATURE
MAX4995A toc02
TEMPERATURE (°C)
NORMALIZED CURRENT LIMIT
-25 5-10 20
0.950
0.975
1.000
1.050
0.925
1.025
1.075
1.100
0.900
-40 50 8065 95 11035 125
MAX4995AL
CURRENT-LIMIT RESPONSE (MAX4995A)
MAX4995A toc03
IOUT
(10A/div)
VOUT
(2V/div)
10
μ
s/div
SUDDEN SHORT
APPLIED AT OUTPUT
CURRENT-LIMIT RESPONSE
MAX4995A toc05
IOUT
(100mA/div)
VOUT
(2V/div)
4ms/div
RLOAD = 8Ω
CURRENT-LIMIT RESPONSE (MAX4995AF)
MAX4995A toc04
IOUT
(10A/div)
VOUT
(2V/div)
10
μ
s/div
SUDDEN SHORT
APPLIED AT OUTPUT
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4995A toc06
SUPPLY VOLTAGE (V)
QUIESCENT SUPPLY CURRENT (μA)
2.0 3.02.5 4.5 5.03.5 4.0
160
180
200
260
280
120
140
220
240
300
100
1.5 5.5
MAX4995A
Typical Operating Characteristics
(VIN = +3.3V, CIN = 1µF, COUT = 1µF, RSETI = 94.2kΩ, TA= +25°C, unless otherwise noted.)
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VIN = +3.3V, CIN = 1µF, COUT = 1µF, RSETI = 94.2kΩ, TA= +25°C, unless otherwise noted.)
QUIESCENT SUPPLY LIMIT
vs. TEMPERATURE
MAX4995A toc07
QUIESCENT SUPPLY CURRENT (μA)
180
190
200
240
170
230
160
220
150
210
250
260
140
VIN = 5V
MAX4995AL
VIN = 3.3V
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX4995A toc08
SHUTDOWN SUPPLY CURRENT (μA)
1.00
0.50
1.50
0.75
1.75
2.00
2.25
0.25
1.25
2.50
0
VIN = 5V
VIN = 3.3V
MAX4995AL
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
SHUTDOWN FORWARD CURRENT
vs. TEMPERATURE
MAX4995A toc09
SHUTDOWN FORWARD CURRENT (nA)
50
70
40
30
20
10
60
80
0
VIN = 5V
VIN = 1.7V
MAX4995C
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
SHUTDOWN REVERSE CURRENT
vs. TEMPERATURE
MAX4995A toc10
SHUTDOWN REVERSE CURRENT (nA)
150
100
125
200
75
50
25
175
225
0
VIN = 5V
MAX4995C
VOUT = 5.5V
VIN = 1.7V
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
MAX4995A toc13
NORMALIZED ON-RESISTANCE
0.9
1.1
1.2
1.3
1.4
0.8
0.7
0.6
1.0
1.5
0.5
MAX4995C
VIN = 3.3V
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
LATCHOFF CURRENT
vs. TEMPERATURE
MAX4995A toc11
LATCHOFF CURRENT (μA)
18
14
16
12
10
8
20
6
VIN = 5V
MAX4995B
VIN = 3.3V
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
NORMALIZED ON-RESISTANCE
vs. SUPPLY VOLTAGE
MAX4995A toc12
SUPPLY VOLTAGE (V)
NORMALIZED ON-RESISTANCE
2.2 4.72.7 3.7 4.23.2
1.010
1.000
1.020
1.005
1.025
1.030
1.035
0.995
0.990
0.985
1.015
1.040
0.980
1.7 5.2
MAX4995C
IOUT < ILIM
SWITCH TURN-ON TIME
vs. TEMPERATURE
MAX4995A toc14
SWITCH TURN-ON TIME (μs)
140
130
120
170
160
150
110
180
100
VIN = 5V
VIN = 3.3V
MAX4995C
ILOAD = 10mA
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
SWITCH TURN-OFF TIME
vs. TEMPERATURE
MAX4995A toc15
SWITCH TURN-OFF TIME (ms)
1.0
1.4
1.5
0.9
0.8
1.3
1.2
1.1
0.7
1.6
0.6
VIN = 5V
VIN = 3.3V
MAX4995C
ILOAD = 10mA
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
6 _______________________________________________________________________________________
SWITCH TURN-ON TIME RESPONSE
MAX4995A toc16
VON
(5V/div)
VOUT
(2V/div)
200
μ
s/div
SWITCH TURN-OFF TIME RESPONSE
MAX4995A toc17
VON
(5V/div)
VOUT
(2V/div)
200
μ
s/div
FLAG RESPONSE (OVERLOAD) CONDITION
MAX4995A toc18
VOUT
(2V/div)
IOUT
(200mA/div)
VFLAG
(2V/div)
100ms/div
SWITCH DROPOUT VOLTAGE
vs. TEMPERATURE
MAX4995A toc19
SWITCH DROPOUT VOLTAGE (mV)
14
12
11
17
13
18
16
15
10
19
9
VIN = 3.3V
MAX4995A
ILOAD = 100mA
TEMPERATURE (°C)
-25 5-10 20-40 50 8065 95 11035 125
IOUT/FLAG vs. VDROP (VIN - VOUT)
MAX4995A toc20
IOUT (mA)
250
150
100
200
300
50
350
0
VIN = 5.5V
MAX4995B
VDROP (mV)
FLAG (LOGIC-LEVEL STATUS)
70 490 5604200
0
1
210 630140 280 350 700
Typical Operating Characteristics (continued)
(VIN = +3.3V, CIN = 1µF, COUT = 1µF, RSETI = 94.2kΩ, TA= +25°C, unless otherwise noted.)
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
_______________________________________________________________________________________ 7
Pin Description
PIN (UTQFN) PIN (TDFN-EP) PIN (SOT23)
MAX4995AL MAX4995_ MAX4995AL MAX4995_ MAX4995AL MAX4995_ NAME FUNCTION
1, 10 1, 10 1, 2 1, 2 5 5 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.
2 2 3 3 6 6 FLAG
Open-Drain, Overload Indicator
Output. FLAG goes low when the
overload fault duration exceeds
the blanking time, reverse current
is detected, thermal shutdown
mode is active, or SETI is
connected to ground.
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
5 5 6 6 3 3 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.
Pin Configurations
35
10 8
IN
*( ) FOR THE MAX4995AL ONLY.
**EXPOSED PAD. CONNECT EP TO GND.
OUT
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
4
9
N.C.
ON (ON)* GND
UTQFN
(1.4mm ×
×
1.8mm)
TOP VIEWS
SETI
ON (ON)*
7 OUT1IN
6 N.C.2FLAG
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
SOT23
(1.6mm
×
2.9mm)
4 ON (ON)*3SETI
5IN2GND
6 FLAG1OUT
1
+
34
865
OUT GND
2
7
N.C.
IN FLAGIN
TDFN
(2mm
×
2mm)
SETI
*EP
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
8 _______________________________________________________________________________________
OUT
SETI
IN
MAX4995A/MAX4995AF/
MAX4995AL/MAX4995B/
MAX4995C
CONTROL
LOGIC
REVERSE-
CURRENT
PROTECTION
THERMAL
SHUTDOWN
CURRENT
LIMIT
BANDGAP
REFERENCE
BUFFER
TIMING
CIRCUITRY
BUFFER
N.C.
FLAG
SOFT-START
ON (ON)*
UVLO
*( ) FOR THE MAX4995AL ONLY.
GND
Functional Diagram
Pin Description (continued)
PIN (UTQFN) PIN (TDFN-EP) PIN (SOT23)
MAX4995AL MAX4995_ MAX4995AL MAX4995_ MAX4995AL MAX4995_ NAME FUNCTION
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.
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
_______________________________________________________________________________________ 9
Detailed Description
The MAX4995A/MAX4995AF/MAX4995AL/MAX4995B/
MAX4995C programmable current-limit switches oper-
ate 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
sec-
tion). 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 pre-
sent for tBLANK. The timer resets if the overcurrent con-
dition 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 ther-
mal 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 pro-
grammed 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.
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 over-
current 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 pack-
age is exceeded during tBLANK, the MAX4995B goes
into thermal shutdown.
Continuous Current Limit (MAX4995C)
When the forward current reaches the forward current-
limit 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 condi-
tion once the short current is detected and the device
shuts down.
Reverse-Current Protection
The MAX4995 features a reverse-current protection cir-
cuit 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).
MAX4995_/
MAX4995AF MAX4995AL
ON ON
SWITCH
STATUS
0 1 Off
10On
Table 1. Switch Truth Table
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
10 ______________________________________________________________________________________
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).
• The die temperature exceeds the thermal-shutdown
temperature limit of +150°C.
• SETI is connected to ground.
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).
tRETRY
tBLANK tBLANK
tBLANK tBLANK
tRETRY
FLAG
OUT
CURRENT LIMIT
LOAD CURRENT THE DEVICE GOES TO
THERMAL-SHUTDOWN MODE
Figure 2. Autoretry Fault Diagram
tBLANK
tBLANK
FLAG
OUT
CURRENT LIMIT
LOAD CURRENT
THE DEVICE GOES TO
THERMAL-SHUTDOWN MODE
Figure 3. Latchoff Fault Diagram
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
______________________________________________________________________________________ 11
Applications Information
Setting the Current Limit
A resistor from SETI to ground programs the current-limit
value for the MAX4995. Table 2 lists various current lim-
its set by different resistor values at SETI. Shorting SETI
to ground asserts FLAG.
Use the following formula to calculate the current limit:
Using an RSETI with a value smaller than 45.8kΩresults
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.
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.
Output Capacitor
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:
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 short-
circuit 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 maxi-
mum 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:
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.
PVI t
tt
MAX IN(MAX) OUT(MAX) BLANK
RETRY BLANK
=××
+
C(F)
I (mA) t (ms )
V(
MAX LIM BLANK(MIN)
IN
μ= ×
V)
R(k)
2
I(A2.48 k
SETI LIM
ΩΩ=−
9042( )
)()
V
m
RSETI (kΩ) TYPICAL CURRENT LIMIT (mA)
45.8 602
55.6 500
70.6 397
94.2 300
143 200
191 150
287 100
576 50
∞ (Open) 0
Table 2. Current Limit vs. Resistor Values
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
12 ______________________________________________________________________________________
MAX4995A/
MAX4995AF/
MAX4995AL/
MAX4995B/
MAX4995C
LOAD
OUT
FLAG
ON
(ON*)
µP
GND
VIO
N.C.
SETI
RSETI
*( ) FOR THE MAX4995AL ONLY.
IN
VCC
1µF
1µF
Typical Operating Circuit
Chip Information
PROCESS: BiCMOS
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
10 UTQFN V101A1CN+1 21-0028
6 SOT23 U6SN+1 21-0058
8 TDFN T822+1 21-0168
Package Information
For the latest package outline information and land patterns,
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.
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
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 ____________________
13
© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 11/08 Initial release. —
1 6/09 Corrected the Ordering Information/Selector Guide. 1, 11
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.
1, 2, 7, 12
