MAX4821 Maxim, MAX4821 Datasheet - Page 8

• Manufacturer Part Number: MAX4821
• Description: The MAX4820/MAX4821 8-channel relay drivers offer built-in kickback protection and drive +3
• Manufacturer: Maxim

+3.3V/+5V, 8-Channel, Cascadable Relay Drivers
with Serial/Parallel Interface
Figure 2. Parallel Interface Timing Diagram (MAX4821 only)
Figure 3. Daisy-Chain Configuration
8
V
LVL
OUT
CS
A_
_______________________________________________________________________________________
SCLK
DIN
CS
DIN
SCLK
CS
t
AS
MAX4820
GND
V
V
CC
CC
0.1μF
DOUT
OUT8
PGND
OUT1
t
LS
SCLK
t
t
t
t
OFF
ON
AH
LH
,
DIN
SCLK
CS
MAX4820
GND
V
V
CC
CC
The MAX4820/MAX4821 feature set and reset inputs that
allow the user to simultaneously turn all outputs on or off
using a single control line. Drive SET low to set all latch-
es and registers to 1 and turn all outputs on. SET over-
rides all serial/parallel control inputs. Drive RESET low to
clear all latches and registers and turn all outputs off.
RESET overrides all other inputs, including SET.
The MAX4820 features a digital output, DOUT, that pro-
vides a simple way to daisy chain multiple devices. This
feature allows the user to drive large banks of relays
using only a single serial interface. To daisy chain multi-
ple devices, connect all CS pins together, and connect
the DOUT of one device to the DIN of another device
(see Figure 3). During operation, a stream of serial data
Table 2. Parallel Interface Address Map
(MAX4821 Only)
0.1μF
DOUT
OUT8
PGND
OUT1
High
High
High
High
Low
Low
Low
Low
A2
Applications Information
High
High
High
High
Low
Low
Low
Low
A1
SCLK
SET / RESET Functions
DIN
SCLK
CS
High
High
High
High
Low
Low
Low
Low
MAX4820
A0
V
GND
V
CC
Daisy Chaining
CC
0.1μF
DOUT
PGND
OUT8
OUT1
OUTPUT
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
OUT7
OUT8