AD22001

REV. A

–3–

SWITCH &

VOLTAGE LIMITER

INTERNAL

POWER SUPPLY

POWER

SUPPLY

OUTPUT

SIGNAL

OUT

GND

2

1

CAR

BATTERY

FUSE

SWITCH

COPPER

SHUNT

LIGHT

BULB

CE

–IN

+IN

NOTES

1. TEMPERATURE COMPENSATION FOR COPPER SHUNT RESISTOR

AND SUPPLY VOLTAGE COMPENSATION.

2. CURRENT SOURCE FOR COLD BULB CHECKING

(AVAILABLE IN CHANNELS 1, 2, 3 AND 4).

+V

S

V

INCE

V

INF

I

INB

V

INDIFF

I

INB

IN

FUSE

I

INC

Figure 2. Typical Block Diagram of One Channel and

Power Supply Control

The AD22001 has internal linear signal processing that compen-

sates the comparator threshold voltage as the resistance of the

copper shunt resistor changes with varying temperature. The

comparator thresholds are also adjusted to compensate for

changes in lamp current due to power supply variations.

The AD22001 was designed for a common automotive lamp

monitoring application. The connection diagram (Figure 3) and

the application suggestion (Figure 4) show the different combi-

nations of functions that are performed for each channel.

FUNCTIONAL DESCRIPTION

The AD22001 consists of fine sensitive comparators with

built-in offset plus biasing and support for comprehensive lamp

circuit monitoring. The comparators are arrayed as a single and

two groups of two (as shown in Figure 3) arranged to meet a

variety of requirements. Two or more AD22001s can be

combined. The comparators are basically similar with additional

features according to their place in the array.

Hot Lamp Test

Each comparator has a differential input with built-in threshold

of 1.75 mV, under nominal operating conditions. The compara-

tors are intended to monitor the voltage developed across a low

resistance shunt by a lamp current. The comparators are active

whenever they are connected to the battery circuit. They indi-

cate normal or okay (the series circuit to the lamp is intact)

when the threshold voltage of 1.75 mV is exceeded. This occurs

when the +input is driven negative with respect to the –input by

a voltage greater than the threshold. They also indicate normal

if they are not activated by common-mode battery voltage,

whether the threshold voltage is exceeded or not. They indicate

a fault if the common-mode is applied but the threshold is not

exceeded.

ABSOLUTE MAXIMUM RATINGS*

Forward Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . +36 V

Reversed Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . –34 V

Forward Transient (40 ms) . . . . . . . . . . . . . . . . . . . . . . +60 V

Reverse Transient (40 ms) . . . . . . . . . . . . . . . . . . . . . . . –40 V

Voltage on Any Input Pin Relative to GND . . . –34 V to +36 V

Operating Temperature (Ambient) . . . . . . . –40

°C to +125°C

Storage Temperature . . . . . . . . . . . . . . . . . . –65

°C to +150°C

*Stresses above those listed under “Absolute Maximum Ratings” may cause

permanent damage to the device. This is a stress rating only, the functional

operation of the device at these or any other conditions above those indicated in the

operational sections of this specification is not implied. Exposure to absolute

maximum rating conditions for extended periods may affect device reliability.

ORDERING INFORMATION

Temperature

Package

Model

Range

Option*

AD22001N –40

°C to +125°C N-20

*N = Plastic DIP Package.

CONNECTION DIAGRAM

1

2

3

4

5

6

7

8

9

10

11

20

19

18

17

16

15

14

12

13

TOP VIEW

(Not to Scale)

AD22001N

CE

–IN 1

+IN 1

FUSE 1 + 2

OUT 1 + 2

+IN 2

–IN 2

+IN 3

GND

FUSE 5

OUT 5

+IN 5

–IN 5

+IN 4

–IN 4

OUT 3 + 4

OUT (3

× 4)

–IN 3

POWER OUT

+V

S

PRODUCT DESCRIPTION

The AD22001’s five comparators each monitor the voltage

across a current sensing shunt resistor which is part of a lamp

circuit. Each comparator has a small threshold voltage, nomi-

nally 1.75 mV. The output of the comparator will change state

as the voltage developed across the shunt (by the lamp current)

crosses the threshold level. Because the threshold voltage is very

small, copper tracks on the PC board can be used as shunt resis-

tors with low power dissipation.