MAX4820 Datasheet, PDF (1/13 Pages) Maxim Integrated Products – +3.3V/+5V, 8-Channel, Cascadable Relay Drivers with Serial/Parallel Interface

19-2751; Rev 0; 1/03
+3.3V/+5V, 8-Channel, Cascadable Relay Drivers
with Serial/Parallel Interface
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 2Ω 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
Pin Configurations continued at end of data sheet.
Typical Application Circuits and Functional Diagrams
appear at end of data sheet.
Features
o 8 Independent Output Channels
o Built-In Inductive Kickback Protection
o Drive +3V and +5V Relays
o Guaranteed 70mA (min) Coil Drive Current
o SET Function to Turn On All Outputs
Simultaneously
o RESET Function to Turn Off All Outputs
Simultaneously
o SPI-/QSPI-/MICROWIRE-Compatible Serial
Interface (MAX4820)
o Serial Digital Output for Daisy Chaining
(MAX4820)
o Parallel Interface (MAX4821)
o Low 50µA (max) Quiescent Supply Current
o Space-Saving 20-Pin Thin QFN Package
Ordering Information
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
*For maximum heat dissipation, packages have an exposed pad
(EP) on the bottom. Solder exposed pad to GND.
Pin Configurations
TOP VIEW
RESET 1
CS 2
DIN 3
SCLK 4
DOUT 5
MAX4820
15 OUT3
14 OUT4
13 COM
12 OUT5
11 OUT6
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
THIN QFN
________________________________________________________________ Maxim Integrated Products 1
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.