TC7126/A

DS21458C-page 8

© 2006 Microchip Technology Inc.

34

(7)

used, a 1

μF capacitor is recommended and will hold the rollover error to 0.5 count.

35

(6)

See Pin 36.

36

(5)

The analog input required to generate a full scale output (1999 counts). Place 100mV

between Pins 35 and 36 for 199.9mV full scale. Place 1V between Pins 35 and 36 for

2V full scale. See Section 6.6 “Reference Voltage Selection”, Reference Voltage

for additional information.

37

(4)

TEST

Lamp test. When pulled HIGH (to V+), all segments will be turned on and the display

should read -1888. It may also be used as a negative supply for externally

generated decimal points. See Section 7.4 “TEST (Pin 37)”, TEST for additional

information.

38

(3)

OSC3

See Pin 40.

39

(2)

OSC2

See Pin 40.

40

(1)

OSC1

Pins 40, 39 and 38 make up the oscillator section. For a 48kHz clock (3 readings,

39 per second), connect Pin 40 to the junction of a 180k

Ω resistor and a 50pF

capacitor. The 180k

Ω resistor is tied to Pin 39 and the 50pF capacitor is tied to

Pin 38.

TABLE 2-1:

PIN FUNCTION TABLE (CONTINUED)

Pin Number

(40-Pin PDIP)

Normal

(Reversed)

Symbol

Description