Datasheet MAX895LESA, MAX894LC-D, MAX894LESA, MAX895LC-D Datasheet (Maxim)

19-1153; Rev 0; 10/96

Dual, Current-Limited, High-Side P-Channel

Switches with Thermal Shutdown

_______________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 current­limiting circuitry protects the input supply against
overload. Thermal-overload protection limits power dis­sipation 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 I

at VIN= 3.3V

Q

0.1µA with Switch Off

♦ Thermal Shutdown

______________Ordering Information

PART*

MAX894LC/D

MAX894LESA -40°C to +85°C
MAX895LC/D
MAX895LESA -40°C to +85°C 8 SO 250mA

*

To order these units in tape and reel, add (-T) to the end of the

part number.

**

Dice are tested at TA= +25°C.

TEMP.

RANGE

0°C to +70°C

0°C to +70°C Dice** 250mA

PIN-

PACKAGE

Dice**
8 SO

CURRENT

LIMIT

500mA
500mA

MAX894L/MAX895L

__________Typical Operating Circuit

OUTPUT A

0.1µF

OUTPUT B

0.1µF1µF

R

SET A

ON/OFF

OUT A

OUT B

MAX894L
MAX895L



SET A

ONA

________________________________________________________________




ONB

SET B

GND

ON/OFF


IN

INPUT

R

SET B

__________________Pin Configuration

TOP VIEW

OUT A

OUT B

SET A

ONA

1

2

MAX894L
MAX895L

3

4

SO

Maxim Integrated Products

ONB

8

IN

7

SET B

6

GND

5

1

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]

Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown

ABSOLUTE MAXIMUM RATINGS

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 (V

Maximum Continuous Switch Current

MAX894L..........................................................................0.75A

MAX895L........................................................................0.375A

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.

+ 0.3V)

IN

Continuous Power Dissipation (T

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

ELECTRICAL CHARACTERISTICS

(VIN= 3V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

CONDITION

Quiescent Current

MAX894L/MAX895L

On-Resistance

Maximum Output Current

I

to I

OUT

ONA, ONB Input Low Voltage
ONA, ONB Input High Voltage
ONA, ONB Input Leakage

I

SETA,ISETB

Turn-On Time
Turn-Off Time 0.8 1.2 20

Note 1: Tested with I

Current Ratio

SET

Bias Current

= 50mA for the MAX894L and 25mA for the MAX895L, and V

OUT

VIN= 5V, ONA = ONB = GND, I

ONA = ONB = IN, VIN= V
ONA = ONB = IN, VIN= 5.5V, V

Rising edge, 1% hysteresis
VIN= 4.5V

VIN= 3.0V
V

required to turn the switch off (Note 1)

SET

MAX894L
MAX895L

= 1.6V to 2.8V

OUT

VIN= 2.7V to 5.5V
VIN= 2.7V to 3.6V
VIN= 4.5V to 5.5V
V

= V

ONA

V

SET A

V

SET B

20% current overdrive, VCC= 5V

VIN= 5V, I
VIN= 3V, I

= 5.5V

ONB

= 1.24V, ONA = 0, ONB = VIN, I
= 1.24V, ONB = 0, ONA = VIN, I

= 250mA (MAX894L), 125mA (MAX895L) 100 200

OUT

= 250mA (MAX894L), 125mA (MAX895L) 150

OUT

OUT A

MAX894L
MAX895L
MAX894L
MAX895L

MAX894L, I
MAX895L, I

OUT A

= V

OUT A

= I

OUT B

= V

OUT
OUT

OUT A
OUT B

OUT B

= 5.5V

OUT B

= 250mA
= 125mA

= 0
= 0

= 0

= 0

raised until VIN- V

SET

= +70°C)

A

18 30

0.03 1Off-Supply Current

0.04 3Off-Switch Current

120 225
250 420
150 300
300 500

500

250
945 1085 1270
910 1050 1235

2.0

2.4

0.01 1

0.5 3

0.5 3
5Slow-Current-Loop Response Time

2Fast-Current-Loop Response Time

≥ 0.8V.

OUT

UNITSMIN TYP MAXPARAMETER

V2.7 5.5Operating Voltage

µA
µA
µA

V2.0 2.4 2.6Undervoltage Lockout

mΩ

V1.178 1.240 1.302Current-Limit-Amplifier Threshold

mA

A/AV

V0.8
V

µA

µA

µs
µs

µs
µs

2 _______________________________________________________________________________________

Dual, Current-Limited, High-Side P-Channel

Switches with Thermal Shutdown

ELECTRICAL CHARACTERISTICS (Note 2)

(VIN= 3V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

CONDITION

Quiescent Current

On-Resistance

I

to I

OUT

Note 2: Specifications to -40°C are guaranteed by design, not production tested.

Current Ratio

SET

VIN= 5V, ONA = ONB = GND, I

ONA = ONB = IN, VIN= V
ONA = ONB = IN, VIN= 5.5V, V

Rising edge, 1% hysteresis
VIN= 4.5V

VIN= 3.0V
V

required to turn the switch off (Note 1)

SET_

V

= 1.24V,

SET

V

= 1.6V to 2.8V

OUT

VIN= 5V

OUT A

MAX894L
MAX895L
MAX894L
MAX895L

MAX894L, I
MAX895L, I

OUT A

= V

OUT A

= I

OUT B

= V

OUT
OUT

= 0

OUT B

= 5.5V

= 0

OUT B

= 250mA
= 125mA 880 1315

50

2.2Off-Supply Current
8Off-Switch Current

250
420
300
500

910 1360

200Turn-On Time

0.25 20Turn-Off Time

MAX894L/MAX895L

UNITSMIN TYP MAXPARAMETER

V3.0 5.5Operating Voltage

µA
µA
µA

V2.0 2.9Undervoltage Lockout

mΩ

V1.14 1.34Current-Limit-Amplifier Threshold

A/A

µs

µs

_______________________________________________________________________________________ 3

Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown

__________________________________________Typical Operating Characteristics

(Typical Operating Circuit, TA= +25°C, unless otherwise noted.)

QUIESCENT CURRENT

vs. INPUT VOLTAGE

28

ONA = ONB = GND

24

20

16

12

8

QUIESCENT CURRENT (µA)

4

0

MAX894L/MAX895L

= I

I

OUT A

0



= 0

OUT B

23

146

INPUT VOLTAGE (V)

MAX894 TOC-01

5

QUIESCENT CURRENT (µA)

OFF-SWITCH CURRENT

vs. TEMPERATURE

OFF-SWITCH CURRENT (µA)

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0

-40

02040

-20 60 100
TEMPERATURE (°C)

80

MAX894 TOC-04

ON

NORMALIZED R

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

QUIESCENT CURRENT

vs. TEMPERATURE

24

22

20

V

= 5V

18

16

14

12

-40 100



020

-20 40 80
TEMPERATURE (°C)

IN

V

= 3V

IN

60

NORMALIZED ON-RESISTANCE

vs. TEMPERATURE

I

= 1/2 I

OUT

LIMIT

-40

02040

-20 60 100
TEMPERATURE (°C)

OFF-SUPPLY CURRENT

vs. TEMPERATURE

0.07

0.06

MAX894 TOC-02

0.05

0.04

0.03

0.02

OFF-SUPPLY CURRENT (µA)

0.01

0

-40



1600
1400

MAX894 TOC-05

1200
1000

RATIO

800

SET

/I

OUT

600

I

400
200

0

80

0 140

02040

-20 60 100
TEMPERATURE (°C)

I

40 60 80

20 100

OUT/ISET

I

LIMIT

vs. I

(%)

LIMIT

MAX894 TOC-03

80

MAX894 TOC-06

120

NORMALIZED OUTPUT CURRENT

vs. OUTPUT VOLTAGE

1.4
V

= 5V

IN

1.2

1.0

0.8

0.6

0.4

NORMALIZED OUTPUT CURRENT

0.2

0

0

23

146

OUTPUT VOLTAGE (V)

5

I

LIMIT

MAX894 TOC-06A



260

I

LOAD = ILIMIT

240



220
200

180

(µs)

160

ON

t

140
120

100

80
60

-40

TURN-ON TIME



vs. TEMPERATURE

VIN = 3V

VIN = 5V

02040

-20 60 100
TEMPERATURE (°C)

80

MAX894 TOC-07

OFF (µs)

t

TURN-OFF TIME

vs. TEMPERATURE

7

I

LOAD = ILIMIT

6

5

4

3

2

1
0

-40

02040

-20 60 100
TEMPERATURE (°C)

4 _______________________________________________________________________________________



MAX894 TOC-08

VIN = 5V

VIN = 3V

80

Dual, Current-Limited, High-Side P-Channel

Switches with Thermal Shutdown

____________________________Typical Operating Characteristics (continued)

(Typical Operating Circuit, TA= +25°C, unless otherwise noted.)

CURRENT-LIMIT RESPONSE

(MAX894L, R

A5V

B

0A

C

0V

C

IN

A: V


= 47µF, C

IN,

= 0.1µF

OUT

500mV/div, AC coupled

2µs/div

= 1Ω)

L

MAX894/895/896 TOC-9

B: I

OUT,

C: V

OUT,

2A/div 

5V/div

A

0A

LOAD-TRANSIENT RESPONSE

(MAX894L)

A

0A
0VBC

C

IN

A: V

CURRENT-LIMIT RESPONSE

(MAX894L, R

= 47µF, C

IN,

= 0.1µF

OUT

500mV/div, AC coupled

1µs/div

= 0.7Ω)

L

MAX894/895/896 TOC-10

B: I

2A/div 

OUT,

C: V

OUT,

5V/div

MAX894L/MAX895L

5V

A

B

VIN = 5V, I
A: V
B: V

SWITCH TURN-ON TIME

= I

OUT

LIMIT

, 2V/div

ON

, 2V/div

OUT

0V

B

MAX494/495/496 TOC-13

A

B

SWITCH TURN-OFF TIME

0V

0V

V
A: V
B: V

= 5V, I

IN

ON
OUT

OUT

, 2V/div

, 2V/div

= I

LIMIT

2µs/div



MAX894/895/896 TOC-12



20µs/div

MAX894/895/896 TOC-11

2ms/div

V

= 5V

IN

A: I

= 0 to 500mA, 0.2A/div

OUT

B: V

RIPPLE, 200mV/div, AC COUPLED

OUT

_______________________________________________________________________________________ 5

Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown

______________________________________________________________Pin Description

PIN

1 OUT A
2 OUT B

3 SET A

4

NAME FUNCTION

Switch A Output. P-channel MOSFET drain. Bypass OUT A with a 0.1µF capacitor to ground.
Switch B Output. P-channel MOSFET drain. Bypass OUT B with a 0.1µF capacitor to ground.
Set Current-Limit Input. A resistor from SET A to ground sets the current limit for switch A. See

ONA

Current Limit

Active-Low Switch A On Input. A logic low turns switch A on.

section.

5 GND Ground

6 SET B

7 IN
8

ONB

Set Current-Limit Input. A resistor from SET B to ground sets the current limit for switch B. See

Current Limit

section.

Input, Switches A and B. P-channel MOSFET source. Bypass IN with a 1µF capacitor to ground.
Active-Low Switch B On Input. A logic low turns switch B on.

MAX894L/MAX895L

P

P

ON

SET A

R

SET A

IN

ON

REPLICA

AMPLIFIER A

Setting the

Setting the

OUT A

P

P

MAX894L
MAX895L

P

CURRENT-LIMIT

AMPLIFIER B

AMPLIFIER B

REPLICA

ON

ON



P

1.24V

OUT B

SET B

R

SET B

CURRENT-LIMIT

AMPLIFIER A

ONA

1.24V

CONTROL 

CIRCUITRY

Figure 1. Functional Diagram

6 _______________________________________________________________________________________

ONB

GND

Dual, Current-Limited, High-Side P-Channel

Switches with Thermal Shutdown

_______________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 (I
(Figure 1). The current-limit error amplifier compares
the voltage across R
and regulates the current back to the lesser of the pro­grammed current limit (I
limit (I

MAX

).

These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.

The MAX894L/MAX895L feature internal current-limiting
circuitry with maximum programmable values (I
500mA, and 250mA, respectively. For best perfor­mance, set the current limit (I
I

LIMIT

≤ I

MAX

throughout the input supply-voltage range.
Program the current limit with a resistor (R

nected from SET_ to ground (Figure 2) as follows:

I

= I

SET

SET

LIMIT

RATIO

LIMIT

= 1.24V / I

is the desired current limit for either switch

is the I

R

where I
and I
the MAX894L and 1050mA for the MAX895L.

The MAX894L/MAX895L are short-circuit-protected
switches. In the event of an output short circuit or cur­rent-overload condition, the current through either switch
is limited by the internal current-limiting error amplifier to

1.5 x I

. When the fault condition is removed, the

LIMIT

replica error amplifier sets the current limit back to I
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 I

. When the fault condition is removed, the current

SET

limit is set back to I
Fast-Loop Response and Output Short-Circuit Slow-Loop
Response in the

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.

/1050) (MAX895) and through R

OUT

to the internal 1.24V reference,

SET

) or the maximum current

LIMIT

SET

Setting the Current Limit

) of

MAX

) between 0.2I

LIMIT

MAX

. This current limit remains in effect

) con-

SET_

/ I

RATIO

SET

OUT

= (1.24V x I

to I

current ratio (1085mA for

SET

RATIO

) / I

LIMIT

Short-Circuit Protection

LIMIT

. Refer to Output Short-Circuit

LIMIT

Typical Operating Characteristics.

Thermal Shutdown

≤

.

SET

R

MAX894L
MAX895L



GND

Figure 2. Setting the Current Limit

SET

__________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 maxi­mum power as follows:

2

where R

P = I

ONA

LIMITA

and R

x R

ONB

ONA

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 increas­es, 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.

2

+ I

LIMITB

x R

ONB

are the on-resistances of

MAX894L/MAX895L

_______________________________________________________________________________________ 7

Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown

___________________Chip Information

TRANSISTOR COUNT: 453
SUBSTRATE CONNECTED TO GND.

MAX894L/MAX895L

__________________________________________________Tape-and-Reel Information

4.0 ±0.1

1.0 ±0.1

1.5 +0.1/-0.0 DIAMETER

2.2 ±0.1

0.5 RADIUS
TYPICAL

B

o

0.30 ±0.05

0.8 ±0.05

0.30R MAX.

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 [phone]

© 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

4.0 ±0.1

Ao = 3.1mm ±0.1
Bo = 2.7mm ±0.1

Ko

Ko = 1.2mm ±0.1


2.0 ±0.05

A0

NOTE: DIMENSIONS ARE IN MM.
AND FOLLOW EIA481-1 STANDARD.

1.75 ±0.1

A

3.5 ±0.05

1.0 MINIMUM

A

8.0 ±0.3