Analog Devices AD22001 Datasheet

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

IN

FUSE

1 & 2

IN

FUSE

5

+V

S

5-Channel Monolithic Comparator

FUSE

+V BATT

SWITCH

COPPER

SHUNT

RESISTOR

LAMP

SIGNAL CONDITIONING

AND SIGNAL PROCESSING

OUTPUT

a

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 228C)
Temperature and Supply Voltage Compensated
Powered Directly from Car Battery: Protection

Included for Transient, Reverse Supply, Load Dump
Operating Temperature Range: –408C to +1258C
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.

for Lamp Monitoring

AD22001*

FUNCTIONAL BLOCK DIAGRAM

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.

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

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] Fax: [phone]

AD22001–SPECIFICA TIONS

(TA = +228C, VS = +13.5 V unless otherwise noted)

Parameter Test Conditions Min Typ Max Units

DIFFERENTIAL INPUTS (Voltage Drop from Shunt Resistor: Pins 4 & 5, 8 & 9, 10 & 11, 14 & 15, 16 & 17)

V

INDIFF

V

INCM

Comparator Threshold Voltage
Common-Mode Threshold Voltage
Power Supply Sensitivity of V

Temperature Compensation of V
I
I

INB
INC

Input Bias Current 10 µA

Constant Current Source

SINGLE-ENDED INPUTS (Fuse Monitoring: Pins 6, 19)

V

INF

Fuse Input Threshold Voltage

1

1
2

INDIFF

INDIFF

4

5

9 V ≤ VS ≤ 16 V 50 %

3

1.5 1.75 2.0 mV
5 V

3770 ppm/°C

30 60 µA

CHIP ENABLE CONTROL INPUT (Pin 1)

V
V

INCE
INCD

Chip Enable, Input High 9 V

Chip Disable (Stop Operation)

6

OUTPUTS (Pins 7, 12, 13, 18)

V

OUTL

Output Voltage, Low Load = 500 µA 0.6 V

Indicates No Fault in Lamp Circuit
V

OUTH

Output Voltage, High 9 V ≤ VS ≤ V

SSDH

V

–2.5 V

OUTPS

Indicates Fault in Lamp Circuit Load = 50 µA

POWER SUPPLY (Pin 2: +V

V

S

I

S

, Pin 20: GND)

S

Supply Voltage 930V

Quiescent Supply Current Pin 1 High 1 3 5 mA

V

: No Load Pin 1 Low 100 µA

OUTH

POWER SUPPLY OUTPUT (Pin 3)

V

OUTPS

I

OUTPS

Power Supply Output Voltage 10 V < VS < 14.5 V VS–0.5 VS–0.3 V

≤ 1 mA

I
Max Output Voltage 16 18 V
Power Supply Output Current

7

OUTPS

2mA

OPERATING SHUTDOWN (Safety Features)

V
V

SSDH

SSDL

Operation Shutdown at High 30 33 36 V
Power Supply Voltages
Operation Shutdown at Low 79V
Power Supply Voltage

8

9

4 V

6 V

OUTPS

S

V

V

TEMPERATURE RANGE

T

A

Operating Temperature Range –40 +125 °C

PACKAGE

Plastic DIP (N-20) AD22001N

NOTES

1

In the presence of a common-mode voltage greater than 5 V, if the shunt voltage applied to the comparator does not exceed the threshold (i.e., the bulb is switched
on but does not draw current), then the device will indicate a failure.

2

At VS = 13.5 V, the differential input threshold voltage is typically 1.75 mV. With an increase of VS, the threshold voltage, V
Power supply sensitivity of 50% means that when the power supply voltage VS increases by 10%, the threshold voltage V
centage value: 5%.

3

This is the temperature coefficient to compensate for any temperature influence on the external copper PCB track shunt resistors. 3770 ppm/°C is equal to 6.6 µV/°C.

4

This current source is used to test the lamp when it is switched off (cold lamp test).

5

If the voltage at the input from the fuse (Pin 6 or 19) does not exceed the threshold voltage, then the output will indicate a failure.

6

When the Chip Enable is open-circuited, the chip is disabled.

7

Shorting V

8

At this voltage, or above, the internal power supply and the power output V

9

Below the minimum voltage, the circuit will shut down. Above the maximum, the circuit will be on if enabled.
All min and max specifications are guaranteed, although only those marked in boldface are tested on all production units at final test.
Specifications subject to change without notice.

to ground will cause the device to stop operating for that period. However, the device will not suffer any damage.

OUTPS

will be shut off.

OUTPS

–2–

, will change as well.

INDIFF

will be increased by half of this per-

INDIFF

REV. A

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

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
Power Dissipation (V

= 13.5 V) . . . . . . . . . . . . . . . . 300 mW

S

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

+V

POWER OUT

–IN 1
+IN 1

FUSE 1 + 2

OUT 1 + 2

+IN 2

–IN 2

+IN 3

CE

S

1
2

3
4
5

6
7
8

9

10

AD22001N

TOP VIEW

(Not to Scale)

20

GND

19

FUSE 5

18

OUT 5

17

+IN 5

16

–IN 5

15

+IN 4

14

–IN 4

13

OUT 3 + 4

12

OUT (3 × 4)

11

–IN 3

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, nomi­nally 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 resis­tors with low power dissipation.

AD22001

Figure 2. Typical Block Diagram of One Channel and
Power Supply Control

The AD22001 has internal linear signal processing that compen­sates 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 combi­nations 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 compara­tors 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 indi­cate 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.

REV. A

–3–