ST ST890 User Manual

1.2 A current limited high side power switch

Features

■ 2.7 V to 5.5 V input range

■ Programmable current limit up to 1.2 A

■ Low quiescent current

■ Thermal shutdown

■ Active low FAULT indicator output

■ 90 mΩ (typ.) ON resistance

■ SO-8 and DFN8L (3 x 3 mm) packages

ST890

with thermal shutdown

SO-8

DFN8L

(3x3mm)

Description

Applications

■ PCMCIA slots

■ Access bus slots

■ Portable equipment

Table 1. Device summary

Order code Package Packaging

ST890BDR SO-8 2500 parts per reel

ST890CDR SO-8 2500 parts per reel

The ST890 is a low voltage, P-channel MOSFET
power switch intended for high side load switching
applications.

The switch operates with inputs from 2.7 V to

5.5 V, making it ideal for both 3 V and 5 V
systems.

The internal current limiting circuitry protects the
input supply against overload. The thermal
overload protection limits power dissipation and
junction temperatures.

The maximum current limit is 1.2 A. The current
limit through the switch is programmed with a
resistor from SET to ground. The devices are
available in SO-8 and DFN8L (3 x 3 mm)
packages.

ST890DTR DFN8L (3 x 3 mm) 3000 parts per reel

March 2009 Rev 8 1/20

www.st.com

20

Contents ST890

Contents

1 Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1.1 Output current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1.2 Output short circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1.3 Programming ILIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1.4 Fault pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1.5 Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.2 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2/20

ST890 Device summary

1 Device summary

Figure 1. SO-8 pin connection (top view)

1

IN

2

IN

3

ON

4

GND

Table 2. SO-8 pin description

Pin N. Symbol Name and function

8

7

6

5

FAULT

OUT

OUT

SET

CS07570

1, 2 IN

3ON

4 GND Ground

5 SET

6,7 OUT

8FAULT

Input P-channel MOSFET source. Bypass IN with a 1 μF
capacitor to ground

Active low switch ON input. A logic low turns the switch ON

Set current limit input. A resistor from SET to GND sets the
current limit for the switch. R
I

is the desired current limit in Amperes

LIM

Switch output. P-channel MOSFET drain. Bypass OUT with
a 0.1 μF capacitor to ground

Fault indicator output. This open drain output goes low
when in current limit or when the die temperature exceeds
135°C

= 1.24x1110/ I

SET

LIM

, where

3/20

Device summary ST890

Figure 2. DFN8L (3 x 3 mm) pin connection (top view)

IN

1

IN

2

ON

3

GND

Table 3. DFN8L (3 x 3 mm) pin description

8

7

6

5

FAULT

OUT

OUT

SET

Pin N. Symbol Name and function

1, 2 IN

3ON

Input P-channel MOSFET source. Bypass IN with a 1 μF
capacitor to ground

Active low switch ON input. A logic low turns the switch ON

4 GND Ground

5 SET

Set current limit input. A resistor from SET to GND sets the
current limit for the switch.

Switch output. P-channel MOSFET drain. Bypass OUT with

6,7 OUT

a 0.1 μF capacitor to ground.
R

= 1.24x1110/I

SET

, where I

LIM

limit in Amperes

Fault indicator output. This open drain output goes low

8FAULT

when in current limit or when the die temperature exceeds
135 °C

is the desired current

LIM

CS00025

4/20

ST890 Device summary

Figure 3. Schematic diagram

IN

/FAULT

/ON

Control

circuitry

­ON

+

ON

-

Current limit

amplifie r

+

Replica

amplifier

OUT

SET

1.24V

GND

CS00026

Table 4. Truth table for ON/OFF switch

ON/OFF OUT

LON

HOFF

Table 5. Truth t a b l e fo r FAULT

FAULT FLAG

H Normal operation

L Fault condition

5/20

Maximum rating ST890

2 Maximum rating

Stressing the device above the rating listed in the “Absolute maximum ratings” table may
cause permanent damage to the device. These are stress ratings only and operation of the
device at these or any other conditions above those indicated in the operating sections of
this specification is not implied. Exposure to Absolute maximum rating conditions for
extended periods may affect device reliability. Refer also to the STMicroelectronics SURE
Program and other relevant quality documents.

Table 6. Absolute maximum ratings

Symbol Parameter Value Unit

V

I

V

ON

V

FAU LT _N

V

SET

I

DS

T

stg

T

op

Table 7. Thermal data

Supply voltage -0.5 to +6 V

Input voltage at ON pin -0.5 to +6 V

Input voltage at FAULT_N pin -0.5 to +6 V

Voltage at SET pin -0.5 to (VIN +0.5) V

Maximum continuous switching current 1.5 A

Storage temperature -65 to +150 °C

Operating ambient temperature range -40 to +85 °C

Symbol Parameter SO-8 DFN8L Unit

R

thj-amb

Thermal

resistance

160

(1)

37.6

(2)

junction-ambient

1. This value depends from thermal design of PCB on which the device is mounted.

2. This value depends from the 4-layer PCB, JEDEC standard test board.

Table 8. Electrical characteristics

Val ue

Symbol Parameter

Test condition

(1)

Min Typ Max

T

= 25°C

A

°C/W

Unit

V

I

CC

Operating voltage ID=1mA 2.7 5.5 V

I

=5V,

V

ON quiescent
supply current

I

= GND

ON
IO = 0

ON =IN
V

I=VOUT

ON

=IN

=5.5V

V

I

V

=0

O

I

(CCOFF)

OFF quiescent
supply current

6/20

=5.5V

13 25 μA

1

μA

5