Maxim MAX4995BAVB+T 50ma to 600ma programmable current-limit switch Datasheet

19-4363; Rev 0; 11/08
50mA to 600mA Programmable
Current-Limit Switches
Features
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 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 package and operate over the -40°C to +125°C
extended temperature range.
♦ 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
Pin Configurations
TOP VIEW
IN
N.C.
OUT
10
9
8
Applications
IN
SDIO Ports
1
USB Ports
FLAG
Notebook VGA Ports
2
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
7
OUT
6
N.C.
GPS
3
Cell Phones
5
4
ON (ON)* GND
SETI
MP3 Players
1.4mm x 1.8mm
UTQFN
UTCA/ATCA Platforms
* ( ) FOR THE MAX4995AL ONLY.
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
Ordering Information/Selector Guide
PART
MAX4995AAUK+T*
MAX4995AAVB+T
MAX4995AFAUK+T*
MAX4995AFAVB+T
MAX4995ALAUK+T*
PINPACKAGE
ON POLARITY
OVERCURRENT
RESPONSE
SHORT-CIRCUIT
RESPONSE
TOP MARK
6 SOT23
ActIve-High
Autoretry
Normal
+ACNZ
10 UTQFN
Active-High
Autoretry
Normal
+AAM
6 SOT23
Active-High
Autoretry
Fast
+ACOE
10 UTQFN
Active-High
Autoretry
Fast
+AAR
6 SOT23
Active-Low
Autoretry
Normal
+ACDA
All devices operate over the -40°C to +125°C temperature range.
+Denotes a lead-free package.
*Future product. Contact factory for availability.
Ordering Information/Selector Guide continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX4995A/AF/AL/MAX4995B/MAX4995C
General Description
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
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 fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.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.
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
5.5
V
170
300
µA
8
15
µA
SUPPLY OPERATION
Operating Voltage
VIN
Quiescent Current
IQ
1.7
IOUT = 0, switch on, VIN = 3.3V
Latchoff Current
ILATCH
VIN = 3.3V, IOUT = 0 after an overcurrent
fault (MAX4995B)
Shutdown Forward Current
ISHDN
VON = 0, VON = VIN, VIN = 5.5V, VOUT = 0
0.01
5
µA
IRSHDN
VON = 0, VON = VIN, VIN = 1.7V,
VOUT = 5.5V (current into OUT)
0.01
1
µA
RON
VIN = 3.3V, IOUT lower than ILIM
130
350
mΩ
Shutdown Reverse Current
INTERNAL FET
Switch-On Resistance
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-currentlimit shutdown
10
µA
Reverse Blocking Threshold
VOUT = VIN + 300mV, OUT falling until switch
turns on
210
mV
FLAG Assertion Drop Voltage
Threshold
VFA
35
Increase (VIN - VOUT) drop until FLAG
asserts, IOUT limiting, VIN = 3.3V
110
650
mV
ON, ON INPUT
ON, ON Input Leakage
ILEAK
ON, ON Input Logic-High Voltage
VIH
ON, ON Input Logic-Low Voltage
VIL
VON, VON = VIN or GND
-1
+1
1.6
µA
V
0.4
V
0.4
V
1
µA
FLAG OUTPUT
FLAG Output Logic-Low Voltage
ISINK = 1mA
FLAG Output Leakage Current
VIN = VFLAG = 5.5V, FLAG deasserted
2
_______________________________________________________________________________________
50mA to 600mA Programmable
Current-Limit Switches
(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
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
tLIM
VIN = 3.3V, RSETI =
578kΩ, output high
and then short-circuit
applied
DYNAMIC
Current-Limit Reaction Time
MAX4995A/AL/B/C
5
µs
MAX4995AF
1.5
Blanking Time
tBLANK
(Note 5)
10
Retry Time
tRETRY
MAX4995A/MAX4995AF/MAX4995AL (Note 5)
320
16.3
22.6
ms
723.2
ms
THERMAL PROTECTION
Thermal Shutdown
Thermal-Shutdown Hysteresis
+150
°C
15
°C
Note 3: ILIM is forward current limit.
ILIM (mA) =
29042(V)
RSETI (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
tRETRY
tBLANK
is a constant value of 32. See Figures 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).
_______________________________________________________________________________________
3
MAX4995A/AF/AL/MAX4995B/MAX4995C
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VIN = +3.3V, CIN = 1µF, COUT = 1µF, RSETI = 94.2kΩ, TA = +25°C, unless otherwise noted.)
CURRENT LIMIT
vs. SUPPLY VOLTAGE
NORMALIZED CURRENT LIMIT
vs. TEMPERATURE
310
MAX4995AL
1.075
NORMALIZED CURRENT LIMIT
MAX4995AL
MAX4995A toc02
1.100
MAX4995A toc01
315
CURRENT LIMIT (mA)
305
300
295
1.050
1.025
1.000
0.975
0.950
290
0.925
285
0.900
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
CURRENT-LIMIT RESPONSE (MAX4995A)
CURRENT-LIMIT RESPONSE (MAX4995AF)
MAX4995A toc03
MAX4995A toc04
SUDDEN SHORT
APPLIED AT OUTPUT
SUDDEN SHORT
APPLIED AT OUTPUT
VOUT
(2V/div)
VOUT
(2V/div)
IOUT
(10A/div)
IOUT
(10A/div)
10μs/div
10μs/div
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
CURRENT-LIMIT RESPONSE
MAX4995A toc05
VOUT
(2V/div)
IOUT
(100mA/div)
280
MAX4995A toc06
300
RLOAD = 8Ω
QUIESCENT SUPPLY CURRENT (μA)
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
MAX4995A
260
240
220
200
180
160
140
120
4ms/div
100
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
SUPPLY VOLTAGE (V)
4
_______________________________________________________________________________________
5.5
50mA to 600mA Programmable
Current-Limit Switches
210
200
190
VIN = 3.3V
170
160
0.75
0.50
VIN = 3.3V
MAX4995A toc09
60
50
VIN = 5V
40
30
20
VIN = 1.7V
10
0
TEMPERATURE (°C)
TEMPERATURE (°C)
SHUTDOWN REVERSE CURRENT
vs. TEMPERATURE
LATCHOFF CURRENT
vs. TEMPERATURE
NORMALIZED ON-RESISTANCE
vs. SUPPLY VOLTAGE
150
VIN = 5V
125
100
75
50
MAX4995B
VIN = 5V
18
16
14
VIN = 3.3V
12
10
VIN = 1.7V
1.040
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
8
6
0
MAX4995A toc12
20
NORMALIZED ON-RESISTANCE
MAX4995C
VOUT = 5.5V
MAX4995A toc11
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAX4995A toc10
0.980
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
SWITCH TURN-ON TIME
vs. TEMPERATURE
SWITCH TURN-OFF TIME
vs. TEMPERATURE
1.3
1.2
1.1
1.0
0.9
0.8
180
170
MAX4995C
ILOAD = 10mA
160
150
VIN = 5V
140
130
120
0.7
VIN = 3.3V
110
0.6
0.5
2.2
2.7
3.2
3.7
4.2
4.7
5.2
1.6
1.5
MAX4995A toc15
MAX4995C
VIN = 3.3V
SWITCH TURN-ON TIME (μs)
MAX4995A toc13
1.5
1.7
SWITCH TURN-OFF TIME (ms)
SHUTDOWN REVERSE CURRENT (nA)
VIN = 5V
1.00
70
-40 -25 -10 5 20 35 50 65 80 95 110 125
25
NORMALIZED ON-RESISTANCE
1.25
MAX4995C
0
175
1.4
1.50
80
-40 -25 -10 5 20 35 50 65 80 95 110 125
225
200
1.75
0.25
MAX4995AL
150
140
2.00
MAX4995A toc14
180
MAX4995AL
SHUTDOWN FORWARD CURRENT (nA)
230
220
2.25
MAX4995A toc08
240
2.50
SHUTDOWN SUPPLY CURRENT (μA)
VIN = 5V
LATCHOFF CURRENT (μA)
QUIESCENT SUPPLY CURRENT (μA)
260
250
SHUTDOWN FORWARD CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX4995A toc07
QUIESCENT SUPPLY LIMIT
vs. TEMPERATURE
MAX4995C
ILOAD = 10mA
1.4
VIN = 5V
1.3
1.2
1.1
1.0
0.9
0.8
VIN = 3.3V
0.7
100
0.6
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
MAX4995A/AF/AL/MAX4995B/MAX4995C
Typical Operating Characteristics (continued)
(VIN = +3.3V, CIN = 1µF, COUT = 1µF, RSETI = 94.2kΩ, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VIN = +3.3V, CIN = 1µF, COUT = 1µF, RSETI = 94.2kΩ, TA = +25°C, unless otherwise noted.)
SWITCH TURN-ON TIME RESPONSE
SWITCH TURN-OFF TIME RESPONSE
MAX4995A toc16
MAX4995A toc17
VON
(5V/div)
VON
(5V/div)
VOUT
(2V/div)
VOUT
(2V/div)
200μs/div
200μs/div
FLAG RESPONSE (OVERLOAD) CONDITION
SWITCH DROPOUT VOLTAGE
vs. TEMPERATURE
MAX4995A toc18
VOUT
(2V/div)
VFLAG
(2V/div)
SWITCH DROPOUT VOLTAGE (mV)
IOUT
(200mA/div)
MAX4995A toc19
19
MAX4995A
ILOAD = 100mA
18
17
16
15
14
13
12
11
10
VIN = 3.3V
9
100ms/div
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
1
MAX4995A toc20
MAX4995B
300
250
200
150
100
FLAG (LOGIC-LEVEL STATUS)
IOUT/FLAG vs. VDROP (VIN - VOUT)
350
IOUT (mA)
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
50
VIN = 5.5V
0
0
0
70 140 210 280 350 420 490 560 630 700
VDROP (mV)
6
_______________________________________________________________________________________
50mA to 600mA Programmable
Current-Limit Switches
PIN (UTQFN)
NAME
FUNCTION
1, 10
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
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
—
ON
Active-Low, Switch-On Input. Drive ON low to turn on the switch.
Active-High, Switch-On Input. Drive ON high to turn on the switch.
MAX4995AL
MAX4995_
1, 10
—
3
ON
4
4
GND
Ground
5
5
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.
6, 9
6, 9
N.C.
No Connect. Not internally connected.
OUT
Switch Output. Bypass OUT with a 1µF capacitor to ground. Connect both outputs (OUT)
together.
7, 8
7, 8
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.
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 t BLANK has
elapsed. The switch turns off if the overcurrent condition
_______________________________________________________________________________________
7
MAX4995A/AF/AL/MAX4995B/MAX4995C
Pin Description
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Functional Diagram
MAX4995A/MAX4995AF/
MAX4995AL/MAX4995B/
MAX4995C
REVERSECURRENT
PROTECTION
IN
OUT
THERMAL
SHUTDOWN
UVLO
CONTROL
LOGIC
BUFFER
FLAG
TIMING
CIRCUITRY
BANDGAP
REFERENCE
N.C.
CURRENT
LIMIT
SETI
BUFFER
SOFT-START
ON (ON)*
GND
*( ) FOR THE MAX4995AL ONLY.
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.
Table 1. Switch Truth Table
MAX4995_/
MAX4995AF
MAX4995AL
ON
ON
Continuous Current Limit (MAX4995C)
0
1
Off
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.
1
0
On
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.
8
SWITCH
STATUS
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).
_______________________________________________________________________________________
50mA to 600mA Programmable
Current-Limit Switches
tRETRY
tBLANK
tRETRY
tBLANK
MAX4995A/AF/AL/MAX4995B/MAX4995C
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
Thermal Shutdown
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:
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 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.
_______________________________________________________________________________________
9
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
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 limits set by different resistor values at SETI. Shorting SETI
to ground asserts FLAG.
Use the following formula to calculate the current limit:
RSETI (kΩ) =
29042(V)
− 2.48 (kΩ)
ILIM (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)
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
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.
10
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:
CMAX (μF) =
ILIM (mA) × tBLANK(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) × IOUT(MAX) × tBLANK
tRETRY + tBLANK
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.
______________________________________________________________________________________
50mA to 600mA Programmable
Current-Limit Switches
PART
MAX4995ALAVB+T
MAX4995BAUK+T*
MAX4995BAVB+T
MAX4995CAUK+T*
MAX4995CAVB+T
PINPACKAGE
ON POLARITY
OVERCURRENT
RESPONSE
SHORT-CIRCUIT
RESPONSE
TOP MARK
10-UTQFN
Active-Low
Autoretry
Normal
+AAN
6 SOT23
Active-High
Latchoff
Normal
+ACDB
10-UTQFN
Active-High
Latchoff
Normal
+AAO
6 SOT23
Active-High
Continuous
Normal
+ACOD
10-UTQFN
Active-High
Continuous
Normal
+AAQ
All devices operate over the -40°C to +125°C temperature range.
+Denotes a lead-free package.
*Future product. Contact factory for availability.
Pin Configurations (continued)
TOP VIEW
OUT
1
GND
2
SETI
3
MAX4995A/MAX4995AF
MAX4995AL/MAX4995B
MAX4995C
6
FLAG
5
IN
4
ON (ON)*
1.6mm x 2.9mm
SOT23
* ( ) FOR THE MAX4995AL ONLY.
______________________________________________________________________________________
11
MAX4995A/AF/AL/MAX4995B/MAX4995C
Ordering Information/Selector Guide (continued)
MAX4995A/AF/AL/MAX4995B/MAX4995C
50mA to 600mA Programmable
Current-Limit Switches
Typical Operating Circuit
VCC
1µF
VIO
IN
OUT
FLAG
1µF
ON
(ON*)
µP
SETI
RSETI
MAX4995A/
MAX4995AF/
MAX4995AL/
MAX4995B/
MAX4995C
LOAD
N.C.
GND
*( ) FOR THE MAX4995AL ONLY.
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
10 UTQFN
V101A1CN+1
21-0028
6 SOT23
U6SN+1
21-0058
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.
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© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.