Features
V
CC
Control
Output
Gnd
Gnd
Gnd
Gnd
Duty cycle
during
short circuit
Overtemp
Shutdown
short circuit
detect
open circuit
detect
I
SOURCE
V
CC(SENSE)
Drive
& Bias
+
+
-
-
Fault
s
Fault Detection
Open Circuit
Short Circuit
Over Temperature
s
V
CC
Sense: Output Turns
On with Loss of V
CC
s
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 cir-
cuit detection in the output on
mode. In addition, the output
driver will turn on (sink current)
when V
CC
is low.
is an
active-low output which reports in
the output-on mode. Internal pull-
up circuitry is provided to ensure
the output pin turns on when the
Control pin is floating.
Fault
Block Diagram
Absolute Maximum Ratings
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65C to 150C
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 183C, 230C peak
Fault
Output
1
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: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
A Company
Electrical Characteristics: 4.75V V
CC
5.25V, -40C T
A
85C; -40 T
J
150C
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.
2
V
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
s Supply Requirements
V
CC
Quiescent Current
Output ON
3
6
mA
V
CC
Quiescent Current
Output OFF
100
250
A
s Output
Leakage Current
V
BAT
=14V
16
100
A
Saturation Voltage
I
OUTPUT
= 350mA
1.1
1.5
V
I
OUTPUT
= 180mA
0.9
1.3
V
V
OUTPUT
(self-bias)
V
CC
< 4.5V, I
OUTPUT
< 200mA
3.5
V
s Current Sense
Short Circuit Current
350
500
650
mA
Open Circuit Current
Output in the ON state
20
40
60
mA
s Control - Input
Input Voltage
Logic = High
2.0
V
Logic = Low
0.8
V
Input Current
Logic = V
CC
20
40
A
Logic = 0V
-50
-20
A
s Fault Output - (Open Collector)
Output Low Voltage
I
FAULT
= 250A (sink)
0.24
0.40
V
s Overtemperature Shutdown
T
J
Output Disable Threshold
(guaranteed by design)
150
180
C
T
J
Hysteresis
(guaranteed by design)
5
C
Note: A fault signal will be shown (at the fault pin) during inrush as the short circuit threshold is exceeded.
CS1108
3
V
BAT
V
CC
Output
Gnd
V
CC
Control
Gnd
CS1108
Gnd
Gnd
Fault
microprocessor
20k
10nF
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 180C (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 cur-
rent will exceed the current limit threshold during the ini-
tial 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 condi-
tion will persist for a brief time until the lamp resistance
has increased enough to reduce its 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 shut-
off the output and the lamp will turn off. Once the die tem-
perature lowers below the thermal threshold then the out-
put will be allowed to turn back on.
Fault
Fault
Thermal Data
8 Lead SO Narrow
(internally fused leads)
R
QJC
typ
25
C/W
R
QJA
typ
110
C/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.
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