ADM9264ARN-REEL データシートの表示（PDF） - Analog Devices

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ADM9264ARN-REEL

Quad Power Supply Monitor for Desktop PCs

Analog Devices 

ADM9264

CIRCUIT INFORMATION

Monitor Inputs SU1 to SU4

The ADM9624 is provided with four analog inputs, SU1 to

SU4, to monitor supply voltages of +12 V, +5 V, +3.3 V and

+2.8 V. Each input is connected to a window comparator con-

sisting of a pair of voltage comparators and a two-input NOR

gate. Each pair of comparators obtains a reference voltage

from a precision internal reference, and each input to be

monitored is connected to the comparators via a precision,

thin film attenuator, whose resistor ratios determine the trip

points of each comparator. As the input voltages are attenu-

ated before reaching the comparators, they may exceed the

supply voltage of the ADM9264 without exceeding the com-

mon-mode or differential input range of the comparators.

When the input voltage is within limits, the outputs of both

comparators are low, so the output of the NOR gate is high. If

the voltage on the inverting input of the low comparator falls

below the reference voltage, or the voltage on the noninverting

input of the high comparator rises above the reference voltage,

the output of the NOR gate will go low.

Error Outputs

Error outputs ERR1 to ERR4 are open-drain outputs that are

OFF (high) when the corresponding input voltage is within

limits and ON (low) when the input is out of limit. Each error

output requires a 10 kΩ pull-up resistor to a positive supply,

which may be different from VCC if required. The open-drain

construction allows two or more of these outputs to be wire-

ANDed together if required.

Auxiliary Inputs ERRX, ERRY

ERRX and ERRY are TTL-compatible auxiliary inputs that

allow external signals such as temperature alarms to be linked

into the ADM9264. ERRX is active high and forces PWROK

low when it is high. ERRY is active low and forces PWROK low

when it is low.

DIS Input

The disable input, DIS, is a TTL-compatible input. It overrides

all other inputs to the PWROK logic and forces PWROK high

when it is high.

SU4DET Input

SU4DET is a TTL-compatible input that disables the ERR4

output, causing ERR4 to go high when SU4DET is high. This

allows the SU4 input to be disabled easily for systems that do

not have a 2.8 V supply.

PWROK Output

The PWROK output combines the four error outputs and the

auxiliary inputs to give a common “Power OK” output. If the

four error outputs are high, ERRX is low, ERRY is high and

DIS is low then PWROK is high, otherwise PWROK is low.

PWROK is an open-drain output and requires a 10K pull-up

resistor to a positive supply, which may be different from VCC if

required. A truth table for the PWROK output is following.

Truth Table

DIS ERRX ERRY ERR4 ERR3 ERR2 ERR1 PWROK

00

1

1

1

1

1

1

0X

X

XXX0

0

0X

X

XX0

X

0

0X

X

X0

XX

0

0X

X

0

XXX

0

0X

0

XXXX

0

01

X

XXXX

0

1X

X

XXXX

1

X = don’t care.

Power Supply VCC

The ADM9264 can be powered from any supply voltage between

2.5 V and 6 V. This includes any of the supply voltages apart

from that connected to SU1, since this is greater than 6 V.

The logic outputs are open-drain and take their output high

level from the voltage connected to the pull-up resistor, so they

are not dependent on the value of VCC.

REV. 0

–5–

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