AD22001N [ADI]

5-Channel Monolithic Comparator for Lamp Monitoring; 5通道单片比较器监测灯


型号：	AD22001N
厂家：	ADI
描述：	5-Channel Monolithic Comparator for Lamp Monitoring 5通道单片比较器监测灯比较器监控
文件：	总8页 (文件大小：150K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

5-Channel Monolithic Comparator

for Lamp Monitoring

AD22001*

FUNCTIO NAL BLO CK D IAGRAM

FEATURES

Continuous Status Checks of Five Bulbs

Lam p Status Check in “ON” and “OFF” States

Status Checks of Tw o In-Line Fuses

POWER

OUT

SWITCH &

LIMITER

CHIP

ENABLE

Very Low Voltage Drop at Sensor Shunt Resistor

(Com parator Threshold 1.75 m V at 22؇C)

Tem perature and Supply Voltage Com pensated

Pow ered Directly from Car Battery: Protection

Included for Transient, Reverse Supply, Load Dum p

Operating Tem perature Range: –40؇C to +125؇C

15 V CMOS Com patible Digital Output Signals

Voltage Lim ited Pow er Supply Output for 15 V CMOS

Logic ICs

GND

AD22001

CHANNEL 1

–IN1

+IN1

1 & 2

OUT 1 & 2

FUSE

–IN2

+IN2

CHANNEL 2

CHANNEL 3

–IN3

+IN3

OUT 3 & 4

GENERAL D ESCRIP TIO N

OUT (3 × 4)

T he AD22001 is a monolithic, five-channel comparator circuit

for monitoring the functionality of lamps in automotive

applications.

–IN4

+IN4

CHANNEL 4

CHANNEL 5

T he IC tests the series circuit leading to the lamp to determine

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

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.

–IN5

+IN5

OUT 5

FUSE

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

OUTPUT

COPPER

SHUNT

RESISTOR

LAMP

SIGNAL CONDITIONING

AND SIGNAL PROCESSING

Figure 1. Typical Application Circuit for a Single Channel Lam p Monitor

REV. A

Inform ation furnished by Analog Devices is believed to be accurate and

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

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

which m ay result from its use. No license is granted by im plication or

otherwise under any patent or patent rights of Analog Devices.

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

Tel: 617/ 329-4700 Fax: 617/ 326-8703

AD22001–SPECIFICATIONS _{(T = +22؇C, V = +13.5 V unless otherwise noted)}

P aram eter

Test Conditions

Min

Typ

Max

2.0

Units

DIFFERENT IAL INPUT S (Voltage Drop from Shunt Resistor: Pins 4 & 5, 8 & 9, 10 & 11, 14 & 15, 16 & 17)

V_INDIFF

V_INCM

Comparator T hreshold Voltage¹

1.5

1.75

ppm/°C

µA

Common-Mode T hreshold Voltage¹

Power Supply Sensitivity of V_INDIFF

9 V ≤ V_S≤ 16 V

3770

T emperature Compensation of V_INDIFF

Input Bias Current

I_INB

I_INC

Constant Current Source⁴

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

V_INF

Fuse Input T hreshold Voltage⁵

CHIP ENABLE CONT ROL INPUT (Pin 1)

V_INCE

V_INCD

Chip Enable, Input High

Chip Disable (Stop Operation)⁶

OUT PUT S (Pins 7, 12, 13, 18)

V_{OUT L}Output Voltage, Low

Load = 500 µA

0.6

Indicates No Fault in Lamp Circuit

Output Voltage, High

V_{OUT H}

9 V ≤ V_S≤ V_SSDH

Load = 50 µA

V_{O UTP S}–2.5

V_{O UTP S}

Indicates Fault in Lamp Circuit

POWER SUPPLY (Pin 2: +V_S, Pin 20: GND)

V_S

I_S

Supply Voltage

Quiescent Supply Current

V_{OUT H}: No Load

µA

Pin 1 High

Pin 1 Low

100

POWER SUPPLY OUT PUT (Pin 3)

V_{OUT PS}Power Supply Output Voltage

10 V < V_S< 14.5 V V_S–0.5

I_{OUT PS}≤ 1 mA

V_S–0.3

V_S

Max Output Voltage

I_{OUT PS}

Power Supply Output Current⁷

OPERAT ING SHUT DOWN (Safety Features)

V_SSDH

Operation Shutdown at High

Power Supply Voltages⁸

Operation Shutdown at Low

Power Supply Voltage⁹

V_SSDL

T EMPERAT URE RANGE

T _A

Operating T emperature Range

Plastic DIP (N-20)

–40

+125

°C

PACKAGE

AD22001N

NOT ES

¹In 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.

²At V_S= 13.5 V, the differential input threshold voltage is typically 1.75 mV. With an increase of V _S, the threshold voltage, V_INDIFF, will change as well.

Power supply sensitivity of 50% means that when the power supply voltage V_Sincreases by 10%, the threshold voltage V_INDIFFwill be increased by half of this per-

centage value: 5%.

³T his 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.

⁴T his current source is used to test the lamp when it is switched off (cold lamp test).

⁵If 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.

⁶When the Chip Enable is open-circuited, the chip is disabled.

⁷Shorting V_{OUT PS}to ground will cause the device to stop operating for that period. However, the device will not suffer any damage.

⁸At this voltage, or above, the internal power supply and the power output V_{OUT PS}will be shut off.

⁹Below 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.

–2–

REV. A

AD22001

SWITCH &

VOLTAGE LIMITER

ABSO LUTE MAXIMUM RATINGS*

CAR

BATTERY

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

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

Forward T ransient (40 ms) . . . . . . . . . . . . . . . . . . . . . . +60 V

Reverse T ransient (40 ms) . . . . . . . . . . . . . . . . . . . . . . . –40 V

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

Power Dissipation (V_S= 13.5 V) . . . . . . . . . . . . . . . . 300 mW

Operating T emperature (Ambient) . . . . . . . –40°C to +125°C

Storage T emperature . . . . . . . . . . . . . . . . . . –65°C to +150°C

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

permanent damage to the device. T his 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.

INTERNAL

POWER SUPPLY

INCE

INF

POWER

SUPPLY

OUTPUT

FUSE

SWITCH

SIGNAL

OUT

–IN

+IN

INB

COPPER

SHUNT

INDIFF

GND

LIGHT

BULB

INB

INC

NOTES

1. TEMPERATURE COMPENSATION FOR COPPER SHUNT RESISTOR

AND SUPPLY VOLTAGE COMPENSATION.

O RD ERING INFO RMATIO N

2. CURRENT SOURCE FOR COLD BULB CHECKING

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

Tem perature

Range

P ackage

O ption*

Model

Figure 2. Typical Block Diagram of One Channel and

Power Supply Control

AD22001N –40°C to +125°C N-20

*N = Plastic DIP Package.

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. T he

comparator thresholds are also adjusted to compensate for

changes in lamp current due to power supply variations.

CO NNECTIO N D IAGRAM

GND

FUSE 5

OUT 5

+IN 5

POWER OUT

–IN 1

T he AD22001 was designed for a common automotive lamp

monitoring application. T he connection diagram (Figure 3) and

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

nations of functions that are performed for each channel.

AD22001N

TOP VIEW

(Not to Scale)

+IN 1

FUSE 1 + 2

OUT 1 + 2

+IN 2

–IN 5

+IN 4

FUNCTIO NAL D ESCRIP TIO N

–IN 4

T he AD22001 consists of fine sensitive comparators with

built-in offset plus biasing and support for comprehensive lamp

circuit monitoring. T he comparators are arrayed as a single and

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

variety of requirements. T wo or more AD22001s can be

combined. T he comparators are basically similar with additional

features according to their place in the array.

OUT 3 + 4

OUT (3 × 4)

–IN 3

–IN 2

+IN 3

P RO D UCT D ESCRIP TIO N

H ot Lam p Test

T he 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. T he 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.

Each comparator has a differential input with built-in threshold

of 1.75 mV, under nominal operating conditions. T he compara-

tors are intended to monitor the voltage developed across a low

resistance shunt by a lamp current. T he comparators are active

whenever they are connected to the battery circuit. T hey indi-

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

when the threshold voltage of 1.75 mV is exceeded. T his occurs

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

a voltage greater than the threshold. T hey also indicate normal

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

whether the threshold voltage is exceeded or not. T hey indicate

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

exceeded.

REV. A

–3–

AD22001

cause their common output, OUT 3 & 4, to indicate failure

(registered as a one or high).

INPUTS AND SUPPLY

OUTPUTS

POWER SUPPLY

OUTPUT

T hese comparators are intended for lamp circuits which are

switched simultaneously, but are fused independently. A special

linkage between the comparators causes them to indicate a fault

if common-mode voltage is applied to only one of the pair. T his

functions as a test of both fuses.

SWITCH &

LIMITER

OUTPS

CHIP

ENABLE

GND

CHANNEL 1

–IN1

+IN1

One additional output is provided which tests when both lamps

are switched on (whether the lamp circuit draws current or not).

T his circuit signals a zero or low level at OUT (3 ϫ 4) whenever

both lamp circuits are powered (implying fuses are present) and

a one or high level otherwise.

SIGNAL OUTPUTS

OUT 1 & 2

1 & 2

FUSE

–IN2

+IN2

CHANNEL 2

CHANNEL 3

D escr iption of Channels 1 and 2

Comparators 1 and 2 are also linked and share a common out-

put. A fault at either input will register as a one or high at OUT

1 & 2. Otherwise this output will be low. Each of these com-

parators also has a cold lamp test current. T hese comparators

are intended for two lamp circuits which have a common fuse,

and a fuse test line, similar to the brake-light test, is brought

out.

–IN3

+IN3

OUT 3 & 4

OUT (3 × 4)

–IN4

+IN4

CHANNEL 4

CHANNEL 5

A summary of the tests performed by each channel is given in

T able I.

–IN5

+IN5

OUT 5

Signal O utputs

T he signal outputs, OUT 1 & 2, OUT 3 & 4, OUT (3 ϫ 4),

and OUT 5, are NPN collectors with pull-up currents provided

by the power control section. T hese currents are about 75 µA

each, and are intended to be sufficient to drive high level CMOS

inputs.

FUSE

Figure 3. AD22001 Connection Diagram

T hus, in the absence of voltage applied to light the lamp, the

lamp resistance holds the common-mode voltage low, and no

fault is indicated. When the lamp circuit is powered, voltage on

the comparator inputs activates the comparator which indicates

a fault if the lamp current does not cause the shunt voltage to

exceed the threshold.

Table I. Sum m ary of Recom m ended Applications and

Tests P erform ed for Each Channel

In a common automotive application, the AD22001 can be used

to monitor the following lamps:

Recom m ended

Applications

Tests

P erform ed

Cold Lam p Test

Channel

In addition to the standard hot lamp test, four of the compara-

tors have a cold lamp test current of about 60 µA applied. If the

lamp circuit is not switched on but the lamp circuit is incom-

plete (failed lamp or connection), the small test current will

raise the common-mode voltage of the comparator at its input

and cause it to indicate a fault. Individual comparator inputs

draw about 10 µA each.

1, 2

Fog Light Front

Fog Light Rear

Number Plate Light

I, II, III

I, II, IV

I, III

3, 4

Low Beam Headlight

Parking/Position

T aillight

D escr iption of Channel 5

T he single comparator in Channel 5 is intended for brake-light

testing. Comparator 5 does not have the cold test feature, since

this lamp is normally tested in conjunction with the brake-light

switch. T he comparator is combined with a fuse test circuit

which checks for battery voltage at its input. T his input

normally connects between the fuse and brake-light switch.

Brake Light

T he following tests are performed and status indicated with the

AD22001:

Test

D escription

T he outputs of the hot lamp test and the fuse test are combined

at OUT 5 which indicates zero or low as the normal or okay

state and one or high if either test fails. T he output will indicate

a fault if battery voltage is lost from the fuse test line, or if the

lamp circuit is powered, but the circuit fails to draw current.

Hot Lamp T est: Lamp is functional.

T est performed while lamp is switched on.

Cold Lamp T est: Lamp is functional.

T est performed while lamp is switched off.

D escr iption of Channels 3 and 4

III

Fuse is in place and functional.

Comparators 3 and 4 are linked to test pairs of lamp circuits. In

addition to the hot lamp test, Channels 3 and 4 each have a cold

lamp test current. A fault for either test at input 3 or 4 will

T he two monitored light bulbs are powered simulta-

neously. T his can be used as an implicit fuse test.

–4–

REV. A

AD22001

Thr eshold Biasing

Copper Resistor s

T he comparators are all activated by a common bias connection

which controls their threshold voltage. T he threshold is

compensated for variations in temperature and operating

voltage. T he temperature compensation is approximately +3770

ppm/°C. T his causes the threshold to track the voltage across a

copper shunt operated at constant current and varying

temperature. T he comparators are intended for use with small

value shunts made using normal copper tracks on PC cards.

Low value resistors can be produced as part of the printed

circuit pattern on copper clad boards. T hese resistors will have a

large positive T C, but this effect is compensated by the

temperature sensitive threshold in the AD22001.

At a design temperature of 24°C the sheet resistance, ρ_S, of 35 µm

copper cladding is about 0.5 milliOhms per square (mΩ/sq),

and 70 µm copper is about 0.25 mΩ/sq. T hat is, a resistor made

from 35 µm copper with an aspect ratio (length/width) of 1 will

have a resistance of 0.5 mΩ, while with an aspect ratio of 4 its

resistance would be 2 mΩ, etc. T he resistor can be designed for

a given value R by noting R = ρ_SL/W, so that L = RW/ρ_S.

+V_BATT

AD22001

CHIP ENABLE

GND

T he sheet resistance ρ_Sis based on the thickness of copper

cladding (with 1 ounce per square foot (oz./ft²) copper at

0.0014" approx. equal to 35 µm, and 2 oz./ft²copper at 0.0028"

approx. equal to 70 µm) and the temperature. Choosing the

resistance value to correspond to the desired current trip level

and AD22001 threshold at 22°C, the 24°C “round number” is

convenient allowing a 2°C gradient from the resistor to the IC.

+V_S

FUSE CHECK

POWER

OUT

OUT 5

FUSE

LAMP

R_S

LAMP

FUSE

Choose W, the track width, as the larger of two values to be

determined. First the conductor should be sized so that the

nominal operating current results in only a small temperature

rise. T his can be determined from the table from MIL ST D-

275C, 9 Jan. 1970 (Figure 8).

LAMP

CHECK

R_S

OUT 1 & 2

LAMP

OUT

3 & 4

R_S

OUT

Second, the width must be great enough to survive the peak

currents which are allowed by the fuse which supplies the track.

T his can be determined from recommendations by the laminate

manufacturer, or the MIL table.

(3 × 4)

LAMP

FUSE

R_S

NOTE

_SARE COPPER-TRACK SHUNT RESISTORS ON THE

PRINTED CIRCUIT BOARD.

Using the larger of the two values determined for W, the length

of the resistor can be calculated. T he resistor is defined by

“Kelvin” connections to the ends which sense the voltage across

this section of the track, and apply it to the differential input of

the AD22001 comparator.

Figure 4. Application Suggestion

T he power supply voltage compensation alters the comparator

threshold with a 50% sensitivity around the nominal 13.5 V

powering voltage. T hat is, a 10% change in battery voltage

results in a 5% change in threshold voltage. T his compensation

approximately tracks the current in a hot lamp which typically

varies nonlinearly with applied voltage, with approximately 50%

sensitivity.

As an example, consider the case of a parking lamp which

nominally draws 325 mA, and is on a circuit fused for 10A.

Suppose the board uses 70 µm (2 oz.) copper cladding, then a

conductor width of a few mils will suffice for the nominal

current. However, the 10A fuse may allow as much as 13.5A

current before it opens. A conductor 0.1" in width will carry

13.5A with less than 50°C rise in temperature, according to the

table.

O N-O FF and P ower Contr ol

T he AD22001 is intended to be powered directly from the

battery voltage. In normal operation an internal switch connects

internal circuits and the Power Out pin to the battery voltage,

under control of the Chip Enable. When Chip Enable is high

(above 9 V) the switch is on, the AD22001 is active and the

Power Out pin will be close to battery potential. When Chip

Enable is low, or open circuit, the switch will open and the

AD22001 will be inactive and Power Out will go low.

Selecting 1/2 the nominal current as the AD22001 trip level

gives:

R = 1.75 mV/(325 mA/2)

or R = 10.769 mΩ.

Substituting these values in the expression for L,

L = 10.769 mΩ ϫ 0.1" /0.25 mΩ per sq

or L = 4.3".

In order to protect the external circuits connected to Power Out

from overvoltage, the power switch is “soft” and limits the

output voltage to typically 16 V. If the applied voltage exceeds

this value, both Power Out and the internal voltage (from which

the threshold is derived) will limit. T he limited Power Out

voltage will be available for moderate overvoltage conditions

such as double battery. If the applied voltage goes above

typically 33 V, the internal switch will be turned off, the lamp

monitor circuits will be inactivated and Power Out will go low

for the duration of the overvoltage.

A track of at least 0.1" in width should be used to convey this

current anywhere on the board. A section 4.3" long should be

sampled by Kelvin connections to the comparator differential

inputs.

T his case, where the peak current available is large while the

sensed current is small, results in extremes of resistor length. In

such cases it may be convenient to bend or fold the shunt

REV. A

–5–

AD22001

resistance track. Bends in the track make the effective L/W more

difficult to calculate, however, certain common cases have been

evaluated.

Assuming equal linear sections, the contacts and the bends

should be made at spacings of 3.412"/4 = 0.853", as shown in

Figure 6.

T o calculate the resistance of a track of width W with a 180°

bend at radius W/2 resulting in a spacing W, add a resistance

equivalent to 2.96 squares to account for the bend. Solving the

resistance equation for L/W,

AD22001

0.853"

(Not to Scale)

FROM SWITCH

L/W = R/ρ_S= 10.769 mΩ/0.25 mΩ/sq,

or L/W = 43 squares.

0.1"

0.05"

0.1"

Subtracting out the bend, the remainder is 40.04 squares.

Converting this to linear dimensions gives 4.004" at W = 0.1".

0.1"

AD22001

(Not to Scale)

2.002"

TO LAMP

0.853"

0.1"

Figure 6. PCB Track Shunt Resistor with Two 180° Bends

0.1"

0.05"

0.1"

A 90° bend with an inside radius of W/2 and a smooth width of

W adds 0.341 squares to the aspect ratio as shown in Figure 7.

Note that the linear measurements are differently made at the

90° and the 180° bend.

TO LAMP

2.002"

Figure 5. PCB Track Shunt Resistor with One 180° Bend

Other styles of bend can be used with minor variation in total

resistance, however, we do not recommend the use of sharp

inside corners on high current conductors in general and shunt

resistors in particular. Sharp inside corners result in very high

local current density and poor resistance repeatability.

As shown in Figure 5, the contacts are made to the resistor

section of the track at 2.002" from the bend. T he bend has a

uniform width of W, which is 0.1" in this case, and a radius of

W/2. As a result, the aspect ratio of the straight sections plus the

bend total 2.96 squares + (2.002" + 2.002")/0.1" or 43 squares.

T he straight sections need not be of equal length, so long as

T hey have the proper total, and the shorter one is longer than

about 3W. A shorter resistor can be made by using more bends

and reducing the linear portion. For example, with three bends

the total length of four linear sections would be:

(43 squares – 3 ϫ 2.96 squares/Bend)W

or (43 – 8.88) ϫ 0.1"= 3.412".

Figure 7. PCB Track Shunt Resistor with 90° Bend

–6–

REV. A

AD22001

35.0

30.0

25.0

100°C

75°C

60°C

20.0

15.0

45°C

12.0

10.0

30°C

20°C

8.0

7.0

6.0

5.0

4.0

10°C

3.0

2.0

1.5

1.0

0.75

0.50

0.25

0.125

0.001

0.005

0.010

0.020

(2 oz/ft²) 0.0028"

0.030

0.050

(3 oz/ft²) 0.0042"

0.070

0.100

(1 oz/ft²) 0.0014"

0.150

0.200

(1/2 oz/ft²) 0.0007"

0.250

0.300

0.350

0.400

20 30

70 100

150

200 250

300 350 400 450 500

600 700

CROSS SECTION – Mils²

Figure 8. Current-Carrying Capacities and Sizes of Etched Copper Conductors for Various Tem perature Rises Above

Am bient (MIL-STD-275C, 9 J anuary 1970)

REV. A

–7–

AD22001

O UTLINE D IMENSIO NS

D imensions shown in inches and (mm).

20-P in P lastic D IP (N) P ackage

1.060 (26.92)

0.925 (23.50)

0.280 (7.11)

0.240 (6.10)

0.325 (8.25)

0.300 (7.62)

PIN 1

0.015 (0.38)

MIN

0.210 (5.33)

MAX

0.150

(3.81)

MIN

0.200 (5.05)

0.125 (3.1)

0.015 (0.381)

0.008 (0.203)

SEATING

PLANE

0.100

(2.54)

BSC

0.070 (1.77)

0.045 (1.15)

0.022 (0.558)

0.014 (0.356)

15°

0°

–8–

REV. A

AD22001N [ADI]

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