AP393

Low Power Low Offset Voltage Dual Comparators

Anachip Corp.

www.anachip.com.tw

Rev. 1.0 Sep 7, 2004

11/13

Application Information

The AP393 is high gain, wide bandwidth devices

which, like most comparators, can easily oscillate if

the output lead is inadvertently allowed to

capacitively couple to the inputs via stray

capacitance. This shows up only during the output

voltage transition intervals as the comparator

change states. Power supply bypassing is not

required to solve this problem. Standard PC board

layout is helpful as it reduces stray input-output

coupling. Reducing the input resistors to < 10kΩ

reduces the feedback signal levels and finally,

adding even a small amount (1.0 to 10 mV) of

positive feedback (hysteresis) causes such a rapid

transition that oscillations due to stray feedback are

not possible. Simply socketing the IC and attaching

resistors to the pins will cause input-output

oscillations during the small transition intervals

unless hysteresis is used. If the input signal is a

pulse waveform, with relatively fast rise and fall

times, hysteresis is not required. All input pins of

any unused comparators should be tied to the

negative supply.

The bias network of the AP393 establishes a drain

current which is independent of the magnitude of

the power supply voltage over the range of from 2.0

bypass capacitor across the power supply line.

The differential input voltage may be larger than V+

without damaging the device (Note 8). Protection

should be provided to prevent the input voltages

An input clamp diode can be used as shown in the

applications section.

The output of the AP393 is the uncommitted

collector of a grounded-emitter NPN output

transistor. Many collectors can be tied together to

provide an output OR’ing function. An output pull-up

resistor can be connected to any available power

supply voltage within the permitted supply voltage

range and there is no restriction on this voltage due

to the magnitude of the voltage which is applied to

the V

can also be used as a simple SPST switch to

ground (when a pull-up resistor is not used). The

amount of current which the output device can sink

is limited by the drive available (which is

independent of V

the

maximum

current

limit

is

reached

(approximately 16mA), the output transistor will

come out of saturation and the output voltage will

rise very rapidly. The output saturation voltage is

transistor. The low offset voltage of the output

transistor (1.0 mV) allows the output to clamp

essentially to ground level for small load currents.

Marking Information

(Top View)

SOP-8L/PDIP-8L

AP393

YY WW X

Logo

Part No.

ID code: internal

Year: "01" =2001

"02" =2002

Xth week: 01~52

5

8

4

1