Datasheet CS1108EDFR8, CS1108EDF8 Datasheet (Cherry Semiconductor)

Features

■ Fault Detection

Open Circuit

Short Circuit

Over Temperature

■ V

CC

Sense: Output Turns

On with Loss of V

CC

■ Low Standby Current

Package Options

CS1108

Single Lamp Driver IC

CS1108

Description

This ASIC provides up to 350mA of
drive current for powering bulbs.
The typical application for this part
is for use in airbag systems using a
type 194 bulb. On chip diagnostics
provide open circuit and short cir­cuit detection in the output on
mode. In addition, the output

driver will turn on (sink current)
when VCCis low. is an
active-low output which reports in
the output-on mode. Internal pull­up circuitry is provided to ensure
the output pin turns on when the
Control pin is floating.

Fault

Block Diagram

Absolute Maximum Ratings

Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65ûC to 150ûC

V

CC

, , Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 6V

ESD Capability (Human Body Model). . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV

Peak Transient Voltage (output off mode, output pin only)

(26V load Dump @ 14V V

BAT

) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40V

Lead Temperature Soldering

Reflow (SMD styles only) . . . . 60 sec. max above 183¡C, 230¡C peak

Fault

Output

V

CC

Gnd

Gnd

Control

Gnd

Gnd

Fault

8 Lead SO

(internally fused leads)

1

Rev. 12/28/98

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: [phone] Fax: [phone]

Email: [e-mail]

Web Site: www.cherry-semi.com

A Company

¨

V

CC

V

CC(SENSE)

I

SOURCE

Drive

& Bias

Output

Control

Fault

Gnd Gnd Gnd

Gnd

Duty cycle

during

short circuit

Overtemp
Shutdown

+

short circuit

-

detect

­open circuit

detect

+

1

Electrical Characteristics: 4.75V ² VCC² 5.25V, -40¡C ² TA² 85¡C; -40¡ ² TJ² 150¡C

CS1108

2

Package Pin Description

PACKAGE PIN # PIN SYMBOL FUNCTION

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

8 Lead SO Narrow

1 Output Open collector output.

2V

CC

5V regulated supply input.

3 Open collector diagnostic output low during open

load, short circuit and overtemperature conditions.

4 Control TTL compatible input.

5, 6, 7, 8 Ground Signal ground.

Fault

■ Supply Requirements

V

CC

Quiescent Current Output ON 3 6 mA

VCCQuiescent Current Output OFF 100 250 µA

■ Output

Leakage Current V

BAT

=14V 16 100 µA

Saturation Voltage I

OUTPUT

= 350mA 1.1 1.5 V

I

OUTPUT

= 180mA 0.9 1.3 V

V

OUTPUT

(self-bias) VCC< 4.5V, I

OUTPUT

< 200mA 3.5 V

■ Current Sense

Short Circuit Current 350 500 650 mA
Open Circuit Current Output in the ON state 20 40 60 mA

■ Control - Input

Input Voltage Logic = High 2.0 V

Logic = Low 0.8 V

Input Current Logic = V

CC

20 40 µA

Logic = 0V -50 -20 µA

■ Fault Output - (Open Collector)

Output Low Voltage I

FAULT

= 250µA (sink) 0.24 0.40 V

■ Overtemperature Shutdown

TJOutput Disable Threshold (guaranteed by design) 150 180 ûC
TJHysteresis (guaranteed by design) 5 ûC

Note: A fault signal will be shown (at the fault pin) during inrush as the short circuit threshold is exceeded.

CS1108

3

Applications Diagram

Circuit Description

The CS1108 lamp driver IC provides up to 350mA of drive
current in a low-side configuration. The Output driver pin
is controlled through the TTL compatible Control input
pin. A high condition on the Control pin turns the output
pin on.

The pin reports short circuit, open circuit, and
overtemperature conditions on the IC. If a fault is present,
the open collector output pin will be low. Typical
numbers for faults are: exceeding 500mA of drive current
will report a short circuit. Less than 40mA (typical) will
report an open circuit. A temperature fault will be reported
when the die temperature exceeds 180¡C (typical). Faults
are only reported when the Control pin is high, due to the
low quiescent current when the Control pin is low and the
output device is turned off.

The CS1108 is designed to provide overcurrent protection
by duty cycle control. When the lamp current exceeds the
internally programmed current limit threshold (typically
500mA), the output enters duty cycle mode to reduce
power dissipation of the IC to a safe level.

Typical lamps have a low resistance when off and the cur­rent will exceed the current limit threshold during the ini­tial inrush period. During this inrush time, the IC will be
operating in the duty cycle mode. Due to characteristics of
lamps in this mode, they may appear dimly lit. This condi­tion will persist for a brief time until the lamp resistance
has increased enough to reduce itÕs current below the
threshold. Once this occurs the lamp will appear at full
brightness. During the inrush period the Fault pin will be
forced low indicating that duty cycle mode is in operation.

Thermal protection has been designed into this IC. Should
duty cycle mode operate for an extended amount of time
and the power limitations of the IC are exceeded the IC die
temperature will rise. Once the die temperature reaches the
thermal temperature limit, the internal circuitry will shut­off the output and the lamp will turn off. Once the die tem­perature lowers below the thermal threshold then the out­put will be allowed to turn back on.

Fault

Fault

VBAT

10nF

20k

V

CC

microprocessor

Output

CS1108

V

CC

Fault

Control

Gnd

Gnd

Gnd

Gnd

Thermal Data 8 Lead SO Narrow

(internally fused leads)

R

QJC

typ 25 ûC/W

R

QJA

typ 110 ûC/W

4

1.27 (.050) BSC

0.51 (.020)

0.33 (.013)

6.20 (.244)

5.80 (.228)

4.00 (.157)

3.80 (.150)

1.57 (.062)

1.37 (.054)

D

0.25 (0.10)

0.10 (.004)

1.75 (.069) MAX

1.27 (.050)

0.40 (.016)

REF: JEDEC MS-012

0.25 (.010)

0.19 (.008)

8 Lead SO Narrow; 150 mil wide

Rev. 12/28/98 © 1999 Cherry Semiconductor Corporation

Package Specification

PACKAGE DIMENSIONS IN mm (INCHES)

D

Lead Count Metric English

Max Min Max Min

8 Lead SO Narrow 5.00 4.80 .197 .189

PACKAGE THERMAL DATA

CS1108

Ordering Information

Part Number Description

CS1108EDF8 8 Lead SO Narrow

(internally fused leads)

CS1108EDFR8 8 Lead SO Narrow

(internally fused leads)
(tape & reel)

Cherry Semiconductor Corporation reserves the right to
make changes to the specifications without notice. Please
contact Cherry Semiconductor Corporation for the latest
available information.