General Description
The MAX894L/MAX895L smart, dual, low-voltage,
P-channel, MOSFET power switches are intended for
high-side load-switching applications. These switches
operate with inputs from +2.7V to +5.5V, making them
ideal for both 3V and 5V systems. Internal current-
limiting circuitry protects the input supply against
overload. Thermal-overload protection limits power dis-
sipation and junction temperature.
The MAX894L/MAX895L’s maximum current limits are
500mA and 250mA, respectively. The current limit
through the switches is programmed with resistors from
SET A/SET B to ground. When the switches are on, the
quiescent supply current is a low 16µA. When the
switches are off, the supply current decreases to 0.1µA.
The MAX894L/MAX895L are available in an 8-pin SO
package.
________________________Applications
PCMCIA Slots
Access Bus Slots
Portable Equipment
____________________________Features
♦+2.7V to +5.5V Input Range
♦Programmable Current Limits
♦Low Supply Current:
16µA IQat VIN = 3.3V
0.1µA with Switch Off
♦Thermal Shutdown
MAX894L/MAX895L
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
________________________________________________________________ Maxim Integrated Products 1
SET B
SET A
GND
1
2
8
7IN
OUT B
OUT A
MAX894L
MAX895L
TOP VIEW
3
4
6
5
ONA
ONB
SO
Pin Configuration
MAX894L
MAX895L
IN INPUT
GND
SET B
OUTPUT B
OUTPUT A
0.1µF
0.1µF1µF
ON/OFF
ON/OFF
ONB
OUT B
SET A
RSET ARSET B
OUT A
ONA
Typical Operating Circuit
19-1153; Rev 1; 2/07
PART*
MAX894LC/D
MAX894LESA -40°C to +85°C
0°C to +70°C
TEMP.
RANGE
PIN-
PACKAGE
Dice**
8 SO
Ordering Information
*To order these units in tape and reel, add (-T) to the end of the
part number.
**Dice are tested at TA= +25°C.
CURRENT
LIMIT
500mA
500mA
MAX895LESA -40°C to +85°C 8 SO 250mA
MAX895LC/D 0°C to +70°C Dice** 250mA
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX894L/MAX895L
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = 3V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN to GND ...................................................................-0.3V to 6V
ONA, ONB to GND .....................................................-0.3V to 6V
SET A, SET B, OUT A, OUT B to GND ........-0.3V to (VIN + 0.3V)
Maximum Continuous Switch Current
MAX894L ..........................................................................0.75A
MAX895L ........................................................................0.375A
Continuous Power Dissipation (TA= +70°C)
SO (derate 5.88mW/°C above +70°C) .......................471mW
Operating Temperature Range
MAX89_LESA .................................................-40°C to +85°C
Storage Temperature Range...............................-65°C to+150°C
Lead Temperature (soldering, 10sec) ..............................+300°C
VSET A = 1.4V, ONA = 0, ONB = VIN, IOUT A = 0,
VIN = VOUT
VONA = VONB = 5.5V
ONA = ONB = IN, VIN = VOUT A = VOUT B = 5.5V
VIN = 4.5V to 5.5V
VIN = 2.7V to 3.6V
VIN = 5V, ONA = ONB = GND, IOUT A = IOUT B = 0
VIN = 2.7V to 5.5V
VIN = 3.0V
MAX895L
ONA = ONB = IN, VIN = 5.5V, VOUT A = VOUT B = 0
Rising edge, 1% hysteresis
MAX894L
VSET required to turn the switch off (Note 1)
CONDITION
0.5 3
ISETA, ISETB Bias Current
µA0.01 1
ONA, ONB Input Leakage
V
2.4
ONA, ONB Input High Voltage 2.0
V0.8
ONA, ONB Input Low Voltage
mA
250
500
Maximum Output Current
V1.178 1.240 1.302Current-Limit-Amplifier Threshold
µA0.0001 1Off-Supply Current
µA18 30
V2.7 5.5Operating Voltage
Quiescent Current
mΩ
300 500
150 300
250 420
µA0.002 10Off-Switch Current
V2.0 2.4 2.6Undervoltage Lockout
On-Resistance
120 225
UNITSMIN TYP MAXPARAMETER
VIN = 4.5V
MAX894L
MAX895L
MAX895L
20% current overdrive, VCC = 5V µs5Slow-Current-Loop Response Time
µs2Fast-Current-Loop Response Time
Note 1: Tested with IOUT = 50mA for the MAX894L and 25mA for the MAX895L, and VSET raised until VIN - VOUT ≥0.8V.
MAX895L, IOUT = 125mA
MAX894L, IOUT = 250mA A/AVOUT > 1.6V 910 1050 1235
945 1085 1270
IOUT to ISET Current Ratio
MAX894L
µA
VIN = 5V, IOUT = 250mA (MAX894L), 125mA (MAX895L) 100 200 µsTurn-On Time VIN = 3V, IOUT = 250mA (MAX894L), 125mA (MAX895L) 150
Turn-Off Time 0.8 1.2 20 µs
VSET B = 1.4V, ONB = 0, ONA = VIN, IOUT B = 0,
VIN = VOUT
0.5 3
MAX894L/MAX895L
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS
(VIN = 3V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)
ONA = ONB = IN, VIN = VOUT A = VOUT B = 5.5V
VIN = 5V, ONA = ONB = GND, IOUT A = IOUT B = 0
VIN = 5V
MAX894L, IOUT = 250mA
VIN = 3.0V
MAX895L
ONA = ONB = IN, VIN = 5.5V, VOUT A = VOUT B = 0
Rising edge, 1% hysteresis
MAX894L
VSET_ required to turn the switch off (Note 1)
CONDITION
VIN = 4.5V
MAX894L
MAX895L
µs200Turn-On Time
A/AVOUT > 1.6V 910 1360
IOUT to ISET Current Ratio
V1.14 1.34Current-Limit-Amplifier Threshold
µA2.2Off-Supply Current
µA50
V3.0 5.5Operating Voltage
Quiescent Current
mΩ
500
300
420
µA10Off-Switch Current
V2.0 2.9Undervoltage Lockout
On-Resistance
225
UNITSMIN TYP MAXPARAMETER
µs0.25 20Turn-Off Time
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
MAX895L, IOUT = 125mA 880 1315
MAX894L/MAX895L
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
4_______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(Typical Operating Circuit, TA= +25°C, unless otherwise noted.)
0
0
QUIESCENT CURRENT
vs. INPUT VOLTAGE
4
8
28
MAX894 TOC-01
INPUT VOLTAGE (V)
QUIESCENT CURRENT (µA)
5
20
12
16
23
24
146
ONA = ONB = GND
IOUT A = IOUT B = 0
12
-40 100
QUIESCENT CURRENT
vs. TEMPERATURE
24
MAX894 TOC-02
TEMPERATURE (°C)
QUIESCENT CURRENT (µA)
60
20
18
22
16
14
020
-20 40 80
VIN = 5V
VIN = 3V
OFF-SUPPLY CURRENT
vs. TEMPERATURE
MAX894L-03
TEMPERATURE (°C)
OFF-SUPPLY CURRENT (nA)
1000
0.01
0.1
1
10
100
-40 20 40 8060-20 0 100
OFF-SWITCH CURRENT
vs. TEMPERATURE
MAX894L-04
TEMPERATURE (°C)
OFF-SWITCH CURRENT (nA)
1000
0.01
0.1
1
10
100
-40 20 40 8060-20 0 100
0
0
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
0.2
0.4
1.4
MAX894 TOC-06A
OUTPUT VOLTAGE (V)
NORMALIZED OUTPUT CURRENT
5
1.0
0.6
0.8
23
1.2
146
VIN = 5V
ILIMIT
-40
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
0.6
0.7
1.3
MAX894 TOC-05
TEMPERATURE (°C)
NORMALIZED RON
80
1.0
0.8
0.9
02040
1.1
1.2
-20 60 100
IOUT = 1/2 ILIMIT
0
0140
IOUT/ISET vs. ILIMIT
200
400
1600
MAX894 TOC-06
ILIMIT (%)
IOUT/ISET RATIO
120
1000
600
800
40 60 80
1200
1400
20 100
60
-40
TURN-ON TIME
vs. TEMPERATURE
80
100
120
260
MAX894 TOC-07
TEMPERATURE (°C)
tON (µs)
80
180
140
160
02040
200
220
240
-20 60 100
ILOAD = ILIMIT
VIN = 5V
VIN = 3V
-40
TURN-OFF TIME
vs. TEMPERATURE
0
1
7
MAX894 TOC-08
TEMPERATURE (°C)
tOFF (µs)
80
4
2
3
02040
5
6
-20 60 100
VIN = 3V
VIN = 5V
ILOAD = ILIMIT
MAX894L/MAX895L
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
_______________________________________________________________________________________ 5
2µs/div
CIN = 47µF, COUT = 0.1µF
A: VIN, 500mV/div, AC coupled
CURRENT-LIMIT RESPONSE
(MAX894L, RL = 1Ω)
A5V
0A
0V
B
C
B: IOUT, 2A/div
C: VOUT, 5V/div
MAX894/895/896 TOC-9
1µs/div
CIN = 47µF, COUT = 0.1µF
A: VIN, 500mV/div, AC coupled
CURRENT-LIMIT RESPONSE
(MAX894L, RL = 0.7Ω)
A
5V
0A
0V
B
C
B: IOUT, 2A/div
C: VOUT, 5V/div
MAX894/895/896 TOC-10
VIN = 5V, IOUT = ILIMIT
A: VON, 2V/div
B: VOUT, 2V/div
SWITCH TURN-ON TIME
A
B
20µs/div MAX894/895/896 TOC-11
SWITCH TURN-OFF TIME
A
B
0V
0V
2µs/div
VIN = 5V, IOUT = ILIMIT
A: VON, 2V/div
B: VOUT, 2V/div
MAX894/895/896 TOC-12
____________________________Typical Operating Characteristics (continued)
(Typical Operating Circuit, TA= +25°C, unless otherwise noted.)
2ms/div
VIN = 5V
A: IOUT = 0 to 500mA, 0.2A/div
B: VOUT RIPPLE, 200mV/div, AC COUPLED
LOAD-TRANSIENT RESPONSE
(MAX894L)
A
0A
0V
B
MAX494/495/496 TOC-13
MAX894L/MAX895L
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
6_______________________________________________________________________________________
NAME FUNCTION
1OUT A Switch A Output. P-channel MOSFET drain. Bypass OUT A with a 0.1µF capacitor to ground.
2OUT B Switch B Output. P-channel MOSFET drain. Bypass OUT B with a 0.1µF capacitor to ground.
PIN
3SET A Set Current-Limit Input. A resistor from SET A to ground sets the current limit for switch A. See Setting the
Current Limit section.
4ONA Active-Low Switch A On Input. A logic low turns switch A on.
8ONB Active-Low Switch B On Input. A logic low turns switch B on.
7IN Input, Switches A and B. P-channel MOSFET source. Bypass IN with a 1µF capacitor to ground.
6SET B Set Current-Limit Input. A resistor from SET B to ground sets the current limit for switch B. See Setting the
Current Limit section.
5GND Ground
______________________________________________________________Pin Description
1.24V
ON
P
P
P
P
P
CURRENT-LIMIT
AMPLIFIER B
REPLICA
AMPLIFIER A
CONTROL
CIRCUITRY
ON
REPLICA
AMPLIFIER B
1.24V
ON
ON
P
CURRENT-LIMIT
AMPLIFIER A
OUT B
OUT A
SET B
RSET B
SET A
RSET A
GND
IN
ONB
ONA
MAX894L
MAX895L
Figure 1. Functional Diagram
MAX894L/MAX895L
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
_______________________________________________________________________________________ 7
_______________Detailed Description
The MAX894L/MAX895L P-channel MOSFET power
switches limit output current to a user-programmed
level. When the output current is increased beyond the
set current level, the current also increases through the
replica switch (IOUT/1050) (MAX895) and through RSET
(Figure 1). The current-limit error amplifier compares
the voltage across RSET to the internal 1.24V reference,
and regulates the current back to the lesser of the pro-
grammed current limit (ILIMIT) or the maximum current
limit (IMAX).
These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.
Setting the Current Limit
The MAX894L/MAX895L feature internal current-limiting
circuitry with maximum programmable values (IMAX) of
500mA, and 250mA, respectively. For best perfor-
mance, set the current limit (ILIMIT) between 0.2IMAX ≤
ILIMIT ≤IMAX. This current limit remains in effect
throughout the input supply-voltage range.
Program the current limit with a resistor (RSET_) con-
nected from SET_ to ground (Figure 2) as follows:
ISET = ILIMIT / IRATIO
RSET = 1.24V / ISET = (1.24V x IRATIO) / ILIMIT
where ILIMIT is the desired current limit for either switch
and IRATIO is the IOUT to ISET current ratio (1085A/A for
the MAX894L and 1050A/A for the MAX895L.
Short-Circuit Protection
The MAX894L/MAX895L are short-circuit-protected
switches. In the event of an output short circuit or cur-
rent-overload condition, the current through either switch
is limited by the internal current-limiting error amplifier to
1.5 x ILIMIT. When the fault condition is removed, the
replica error amplifier sets the current limit back to ILIMIT.
For a high ∆VDS/∆t during an output short-circuit condi-
tion, the switch turns off and disconnects the input supply
from the output. The current-limiting amplifier then slowly
turns the switch on with the output current limited to
1.5 x ISET. When the fault condition is removed, the current
limit is set back to ILIMIT. Refer to Current-Limit Response
graphs in the Typical Operating Characteristics.
Thermal Shutdown
The MAX894L/MAX895L feature thermal shutdown. The
switch turns off when the junction temperature exceeds
+135°C. Once the device cools by 10°C, the switch turns
back on. If the fault short-circuit condition is not
removed, the switch cycles on and off, resulting in a
pulsed output.
__________Applications Information
Input Capacitor
To limit input voltage drop during momentary output
short-circuit conditions, place a capacitor from IN to
GND. A 1µF ceramic capacitor is adequate for most
applications; however, higher capacitor values further
reduce voltage drop at the input.
Output Capacitor
Connect a 0.1µF capacitor from OUT to GND. This
capacitor prevents inductive parasitics from pulling
OUT negative during turn-off.
Layout and Thermal-Dissipation
Consideration
To take full advantage of the switch-response time to
output short-circuit conditions, it is very important to
keep all traces as short as possible, reducing the effect
of undesirable parasitic inductance. Place input and
output capacitors as close as possible to the device
(no more than 5mm).
Under normal operating conditions, the package can
dissipate and channel heat away. Calculate the maxi-
mum power as follows:
P = I2LIMITA x RONA + I2LIMITB x RONB
where RONA and RONB are the on-resistances of
switches A and B, respectively.
When one or both outputs are short circuited, the volt-
age drop across the switch equals the input supply.
Hence, the power dissipated across the switch increas-
es, as does the die temperature. If the fault condition is
not removed, the thermal-overload-protection circuitry
turns the switch off until the die temperature falls by
10°C. A ground plane in contact with the device helps
to further dissipate heat.
MAX894L
MAX895L
SET
RSET
GND
Figure 2. Setting the Current Limit
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
MAX894L/MAX895L
___________________Chip Information
TRANSISTOR COUNT: 453
SUBSTRATE CONNECTED TO GND.
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.
8_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
©2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Revision History
Pages changed at Rev 1: 1, 7, 8
4.0 ±0.1
0.30 ±0.05
0.8 ±0.05
0.30R MAX.
Bo
Ko
2.2 ±0.1
0.5 RADIUS
TYPICAL A0
4.0 ±0.1
2.0 ±0.05
1.5 +0.1/-0.0 DIAMETER 1.75 ±0.1
1.0 ±0.1
A
8.0 ±0.3
3.5 ±0.05
1.0 MINIMUM
A
Ao = 3.1mm ±0.1
Bo = 2.7mm ±0.1
Ko = 1.2mm ±0.1
NOTE: DIMENSIONS ARE IN MM. AND
FOLLOW EIA481-1 STANDARD.
Tape-and-Reel Information
