Datasheet

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PIN NAME FUNCTION

1 DIN Serial-Data Input. Data is loaded into the internal 16-bit shift register on CLK’s rising edge.

2, 3, 5–8,

10, 11

DIG 0–DIG 7

Eight-digit drive lines that sink current from the display common cathode. The MAX7219 pulls

the digit outputs to V+ when turned off. The MAX7221’s digit drivers are high-impedance when

turned off.

4, 9 GND Ground. Both GND pins must be connected.

LOAD

(MAX7219)

Load-Data Input. The last 16 bits of serial data are latched on LOAD’s rising edge.

(MAX7221)

Chip-Select Input. Serial data is loaded into the shift register while CS is low. The last 16 bits of

serial data are latched on CS’s rising edge.

13 CLK

Serial-Clock Input. 10MHz maximum rate. On CLK’s rising edge, data is shifted into the internal

shift register. On CLK’s falling edge, data is clocked out of DOUT. On the MAX7221, the CLK

input is active only while CS is low.

14–17,

20–23

SEG A–SEG G,

Seven Segment Drives and Decimal Point Drive that source current to the display. On the

MAX7219, when a segment driver is turned off it is pulled to GND. The MAX7221 segment

drivers are high-impedance when turned off.

18 ISET

Connect to V

through a resistor (R

SET

) to set the peak segment current (Refer to Selecting

SET

Resistor and Using External Drivers section).

19 V+ Positive Supply Voltage. Connect to +5V.

24 DOUT

Serial-Data Output. The data into DIN is valid at DOUT 16.5 clock cycles later. This pin is used

to daisy-chain several MAX7219/MAX7221’s and is never high-impedance.

Functional Diagram

Pin Description

( ) MAX7221 ONLY

V+

SET

LOAD (CS)

DIN DOUT

CLK

(MSB)(LSB)

SEG A–SEG G, DP

DIG 0–DIG 7

SHUTDOWN REGISTER

MODE REGISTER

INTENSITY REGISTER

SCAN-LIMIT REGISTER

DISPLAY-TEST REGISTER

INTENSITY

PULSE-

WIDTH

MODULATOR

MULTIPLEX

SCAN

CIRCUITRY

ADDRESS

DECODER

8x8

DUAL-PORT

SRAM

D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12

DIGIT DRIVERS

D13 D14 D15

CODE B

ROM WITH

BYPASS

SEGMENT

CURRENT

REFERENCE

SEGMENT DRIVERS

MAX7219/MAX7221 Serially Interfaced, 8-Digit LED Display Drivers

www.maximintegrated.com

Maxim Integrated

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