FUNCTIONAL BLOCK DIAGRAM

SWITCH &

LIMITER

4

5

6

9

8

CHANNEL 1

CHANNEL 2

CHANNEL 3

2

1

20

3

7

11

10

13

12

CHANNEL 4

CHANNEL 5

14

15

16

17

19

18

CHIP

ENABLE

GND

+IN1

–IN1

–IN2

+IN2

–IN3

+IN3

–IN4

+IN4

–IN5

+IN5

POWER

OUT

OUT 1 & 2

OUT 3 & 4

OUT (3

× 4)

OUT 5

AD22001

REV. A

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

a

5-Channel Monolithic Comparator

for Lamp Monitoring

AD22001*

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

Fax: 617/326-8703

FEATURES

Continuous Status Checks of Five Bulbs

Lamp Status Check in “ON” and “OFF” States

Status Checks of Two In-Line Fuses

Very Low Voltage Drop at Sensor Shunt Resistor

(Comparator Threshold 1.75 mV at 22 C)

Temperature and Supply Voltage Compensated

Powered Directly from Car Battery: Protection

Included for Transient, Reverse Supply, Load Dump

Operating Temperature Range: –40 C to +125 C

15 V CMOS Compatible Digital Output Signals

Voltage Limited Power Supply Output for 15 V CMOS

Logic ICs

GENERAL DESCRIPTION

The AD22001 is a monolithic, five-channel comparator circuit

for monitoring the functionality of lamps in automotive

applications.

The IC tests the series circuit leading to the lamp to determine

if the circuit is intact and a functional lamp is in the socket. The

AD22001 continuously checks the functionality of up to five

bulbs in either their “on” or “off” state, and also tests for the

presence of an in-line fuse in two of the series circuits.

Digital outputs indicate the status of each channel. Additionally,

the AD22001 provides a voltage limited power supply output to

supply 15 V CMOS circuits that may interface to the AD22001.

FUSE

+V BATT

SWITCH

COPPER

SHUNT

RESISTOR

LAMP

SIGNAL CONDITIONING

AND SIGNAL PROCESSING

OUTPUT

Figure 1. Typical Application Circuit for a Single Channel Lamp Monitor