Rainbow Electronics MAX4821 - Manual

General Description
The MAX4820/MAX4821 8-channel relay drivers offer
built-in kickback protection and drive +3.3V/+5V non-
latching or dual-coil-latching relays. These devices are
especially useful when driving +3V relays. Each inde-
pendent open-drain output features a 2
Ω on-resistance
and is guaranteed to sink 70mA (min) of load current.
Both devices consume less than 50µA (max) quiescent
current and have 1µA output off-leakage current.
The MAX4820 features an SPI™-/QSPI™-/MICROWIRE™-
compatible serial interface. Input data is shifted into an 8-
bit shift register and latched to the outputs when CS
transitions from low to high. Each data bit in the shift reg-
ister corresponds to a specific output, allowing indepen-
dent control of all outputs.
The MAX4821 features a 4-bit (A0, A1, A2, LVL) paral-
lel-input interface. The first three bits (A0, A1, A2) deter-
mine the output address, and the fourth bit (LVL)
determines whether the selected output is switched on
or off. Data is latched to the outputs when CS transi-
tions from low to high.
Both devices feature separate set and reset functions
that allow the user to turn on or turn off all outputs simul-
taneously with a single control line. Built-in hysteresis
(Schmidt trigger) on all digital inputs allows this device
to be used with slow rising and falling signals, such as
those from optocouplers or RC power-up initialization
circuits. The MAX4820/MAX4821 are available in 20-pin
TSSOP and space-saving 20-pin thin QFN packages.
Applications
Central Office
ATE
DSL, ADSL Line Cards
Industrial Equipment
E1/T1 Redundancy
Features
♦ 8 Independent Output Channels
♦ Built-In Inductive Kickback Protection
♦ Drive +3V and +5V Relays
♦ Guaranteed 70mA (min) Coil Drive Current
♦ SET Function to Turn On All Outputs
Simultaneously
♦ RESET Function to Turn Off All Outputs
Simultaneously
♦ SPI-/QSPI-/MICROWIRE-Compatible Serial
Interface (MAX4820)
♦ Serial Digital Output for Daisy Chaining
(MAX4820)
♦ Parallel Interface (MAX4821)
♦ Low 50µA (max) Quiescent Supply Current
♦ Space-Saving 20-Pin Thin QFN Package
MAX4820/MAX4821
+3.3V/+5V, 8-Channel, Cascadable Relay Drivers
with Serial/Parallel Interface
________________________________________________________________ Maxim Integrated Products 1
TOP VIEW
20 19 18 17
SET V
CC
OUT1 OUT2
16
PGND
13
12
11
14
15
OUT5
COM
OUT4
OUT3
OUT6
4
3
2
1
SCLK
DIN
CS
RESET
5 DOUT
6 7 8 9
N.C. GND
OUT8 OUT7
10
PGND
MAX4820
THIN QFN
Pin Configurations
Ordering Information
19-2751; Rev 0; 1/03
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
*For maximum heat dissipation, packages have an exposed pad
(EP) on the bottom. Solder exposed pad to GND.
Pin Configurations continued at end of data sheet.
Typical Application Circuits and Functional Diagrams
appear at end of data sheet.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
PART TEMP RANGE PIN-PACKAGE
MAX4820ETP* -40°C to +85°C 20 Thin QFN-EP
MAX4820EUP* -40°C to +85°C 20 TSSOP
MAX4821ETP* -40°C to +85°C 20 Thin QFN-EP
MAX4821EUP* -40°C to +85°C 20 TSSOP