6-13

TELCOM SEMICONDUCTOR, INC.

7

6

5

4

3

1

2

8

Binary Input

Character Displayed

B3

B2

B1

B0

(Code B)

0000

0

0001

1

0010

2

0011

3

0100

4

0101

5

0110

6

0111

7

1000

8

1001

9

1010

—

1011

E

1100

H

1101

L

1110

P

1111

Blank

portion duration is less than 1

µsec. The backplane disable

sensing circuit will not respond to such a short signal.

Input Configuration and Output Codes

The TC7211AM accepts a 4-bit, true binary (positive

level = logic “1”) input at pin 27 (LSB) through pin 30 (MSB).

The binary input is decoded to the 7-segment output known

as Code B. The output display format is 0 to 9, —, E, H, L,

P and blank display (see Table 1). Segment assignments

are shown in Figure 4. The TC7211AM will correctly decode

binary and BCD true codes to a 7-segment output.

The TC7211AM is designed to interface with a data bus

and display data under microprocessor control. Four data

inputs (pins 27–30) and two digit select input bits (pins 31

and 32) are written into input buffer latches. The rising edge

of either chip select causes data to be latched, decoded and

stored in the selected digit output data latch. The 2-bit digit

code selects the appropriate output digit latch. The 4-bit

display data word is decoded to the "Code B" 7-segment

output format.

For applications where bus compatibility is not required,

refer to the TC7211AM (LCD) 4-digit decoder driver data

sheet. This device is designed to accept multiplexed BCD/

binary input data for display under the control of four sepa-

rate digit select control signals.

Figure 3. TC7211AM Driving an 8-Digit LCD Display

in Master/Slave Configuration

Figure 4. Segment Assignment

Special Order Decoder Option

The TC7211AM is mask programmed to give the 16

combinations of 7-segment output codes. For large volume

orders (50K pieces minimum), custom decoder options are

available. Contact TelCom Semiconductor for details.

D8 D7 D6 D5 D4

D3 D2 D1

8-DIGIT

LCD

BACKPLANE

SLAVE

BCD/BINARY

DATA

BACKPLANE

MASTER

BACKPLANE

28

+5V

4

4

4

V+

GND

OSC

SEGMENTS

HIGH ORDER

B3–

B0 CS1

BP

+5V

V+

GND

OSC

SEGMENTS

HIGH ORDER

B3–

B0

BP

TC7211AM

28

DS1

CS2

DS2

CS1

DS1

CS2

DS2

CHIP

SELECT

DIGIT

SELECT

G

A

B

C

F

E

D

Table 1. Binary Codes Versus Character Displayed

BUS COMPATIBLE, 4-DIGIT

CMOS DECODER/DRIVER

TC7211AM