MAX6955_15 Datasheet, PDF (18/40 Pages) Maxim Integrated Products – 2-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan

MAX6955
2-Wire Interfaced, 2.7V to 5.5V
LED Display Driver with I/O
Expander and Key Scan
LED OUTPUT O0
LED OUTPUT O1
LED OUTPUT O2
LED OUTPUT O3
LED OUTPUT O4
LED OUTPUT O5
LED OUTPUT O6
LED OUTPUT O7
VCC
KEY_A (P0)
KEY_B (P1)
KEY_C (P2)
KEY_D (P3)
IRQ (P4)
SW A0
SW A1
SW A2
SW A3
SW A4
SW A5
SW A6
SW A7
MICROCONTROLLER INTERRUPT
Figure 11. Key-Scanning Configuration
SW B0
SW B1
SW B2
SW B3
SW B4
SW B5
SW B6
SW B7
SW C0
SW C1
SW C2
SW C3
SW C4
SW C5
SW C6
SW C7
SW D0
SW D1
SW D2
SW D3
SW D4
SW D5
SW D6
SW D7
LED0
LED1
LED2
LED3
LED4
LED5
LED SEGMENT IS OPTIONAL AND
BASED ON APPLICATION.
LED OUTPUT 00
LED OUTPUT 01
LED OUTPUT 02
LED OUTPUT 03
LED OUTPUT 04
LED OUTPUT 05
LED OUTPUT 06
LED OUTPUT 07
A 25.6MS KEY-SCAN CYCLE
12.8MS FIRST HALF KEY-SCAN CYCLE
1.6ms MULTIPLEX CYCLE 1
1.6ms MULTIPLEX CYCLE 2
12.5µs TO 187.5µs DIGIT PERIOD
1.6ms MULTIPLEX CYCLE 8
12.8MS SECOND HALF KEY-SCAN CYCLE
1.6ms MULTIPLEX CYCLE 1
1.6ms MULTIPLEX CYCLE 6
FIRST KEY TEST
PERIOD
START
END
START
SECOND KEY TEST
PERIOD
(DEBOUNCE)
END START OF NEXT KEY-SCAN CYCLE
Figure 12. Key-Scan Timing Diagram
INTERRUPT ASSERTED IF PERIOD
DEBOUNCE REGISTER UPDATED
www.maximintegrated.com
Maxim Integrated | 18