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.
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
Features
MAX4820/MAX4821
Ordering Information
PART
MAX4820ETP*
MAX4820EUP*
MAX4821ETP*
MAX4821EUP*
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 Thin QFN-EP
20 TSSOP
20 Thin QFN-EP
20 TSSOP
Applications
Central Office
ATE
DSL, ADSL Line Cards
*For
maximum heat dissipation, packages have an exposed pad
(EP) on the bottom. Solder exposed pad to GND.
Pin Configurations
PGND
OUT1
18
20
19
17
RESET
CS
1
2
3
4
5
10
6
7
8
9
16
E1/T1 Redundancy
V
CC
SET
Industrial Equipment
OUT2
TOP VIEW
15
14
OUT3
OUT4
COM
OUT5
OUT6
Pin Configurations continued at end of data sheet.
Typical Application Circuits and Functional Diagrams
appear at end of data sheet.
DIN
SCLK
DOUT
MAX4820
13
12
11
N.C.
OUT8
OUT7
GND
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
THIN QFN
1
________________________________________________________________
Maxim Integrated Products
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.
PGND
+3.3V/+5V, 8-Channel, Cascadable Relay Drivers
with Serial/Parallel Interface
MAX4820/MAX4821
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.)
V
CC
, COM..............................................................-0.3V to +6.0V
OUT_........................................................-0.3V to (V
COM
+ 0.3V)
CS,
SCLK, DIN,
SET, RESET,
A0, A1, A2, LVL......-0.3V to +6.0V
DOUT..........................................................-0.3V to (V
CC
+ 0.3V)
Continuous OUT_ Current (all outputs turned on) ............150mA
Continuous OUT_ Current (single output turned on) ........300mA
Continuous Power Dissipation (T
A
= +70°C)
20-Lead Thin QFN
(derate 16.9mW/°C above +70°C) .................................1350mW
θ
JA
.........................................................................59.3°C/W
20-Pin TSSOP
(derate 21.7mW/°C above +70°C) .................................1739mW
θ
JA
............................................................................46°C/W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Soldering Temperature (10s) ...........................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +3V to +5.5V, V
COM
= V
CC
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Operating Voltage
Quiescent Current
Thermal Shutdown
Power-On Reset
Power-On Reset Hysteresis
DIGITAL INPUTS (SCLK, DIN,
CS,
LVL, A0, A1, A2,
RESET, SET)
Input Logic High Voltage
Input Logic Low Voltage
Input Logic Hysteresis
Input Leakage Currents
C
IN
Input Capacitance
DIGITAL OUTPUT (DOUT)
DOUT Low Voltage
DOUT High Voltage
V
OL
V
OH
I
SINK
= 6mA
I
SOURCE
= 0.5mA
V
CC
= 2.7V
V
CC
= 4.5V
R
ON
V
OUT
_
I
LEAK
V
FORW
V
CC
= 2.7V
V
CC
= 3.0V, I
OUT
_ = 70mA
V
OUT
_ = V
CC
, all outputs off
I
OUT
_ = 150mA (Note 2)
-1
V
CC
- 0.5
70
70
2
6
0.4
+1
1.5
0.4
V
V
V
IH
V
IL
V
HYST
I
LEAK
C
IN
Input voltages = 0 or 5.5V
-1.0
V
CC
= 3.3V
V
CC
= 5V
V
CC
= 3.3V
V
CC
= 5V
150
0.01
5
+1.0
2.0
2.4
0.6
0.8
V
V
mV
µA
pF
0.8
SYMBOL
V
CC
I
Q
I
OUT
_ = 0,
logic inputs = 0 or V
CC
V
CC
= 3.6V
V
CC
= 5.5V
CONDITIONS
MIN
2.3
15
20
160
1.5
140
2.2
TYP
MAX
5.5
50
70
UNITS
V
µA
°C
V
mV
RELAY OUTPUT DRIVERS (OUT1–OUT8)
OUT_ Drive Current
OUT_ On-Resistance
OUT_ Voltage
I
OUT
Off-Leakage Current
Kickback Diode Forward Voltage
mA
Ω
V
µA
V
2
_______________________________________________________________________________________
3.3V/+5V, 8-Channel, Cascadable Relay Drivers
with Serial/Parallel Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3V to +5.5V, V
COM
= V
CC
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SPI TIMING (MAX4821)
Turn-On Time (OUT_)
Turn-Off Time (OUT_)
SCLK Frequency
Cycle Time
CS
Fall to SCLK Rise Setup
CS
Rise to SCLK Hold
SCLK High Time
SCLK Low Time
Data Setup Time
Data Hold Time
SCLK Fall to DOUT Valid
Rise Time (DIN, SCLK,
CS, SET,
RESET)
Fall Time (DIN, SCLK,
CS,
RESET, SET)
RESET
Min Pulse Width
SET
Min Pulse Width
PARALLEL TIMING (MAX4820)
Turn-On Time
Turn-Off Time
LVL Setup Time
LVL Hold Time
Address to
CS
Setup Time
Address to
CS
Hold Time
Rise Time (A2, A1, A0, LVL)
Fall Time (A2, A1, A0, LVL)
RESET
Pulse Width
SET
Pulse Width
t
ON
t
OFF
t
LS
t
LH
t
AH
t
AS
t
SCR
t
SCF
t
RW
t
SW
20% of V
CC
to 70% of V
CC
, C
L
= 50pF
20% of V
CC
to 70% of V
CC
, C
L
= 50pF
70
70
From rising edge of
CS,
R
L
= 50Ω,
C
L
= 50pF
From rising edge of
CS,
R
L
= 50Ω,
C
L
= 50pF
100
0
100
0
2
2
1
1
µs
µs
ns
ns
ns
ns
µs
µs
ns
ns
t
ON
t
OFF
f
SCLK
t
CH
+ t
CL
t
CSS
t
CSH
t
CH
t
CL
t
DS
t
DH
t
DO
t
SCR
t
SCF
t
RW
t
SW
50% of SCLK to 10% of DOUT,
C
L
= 50pF
20% of V
CC
to 70% of V
CC
, C
L
= 50pF
20% of V
CC
to 70% of V
CC
, C
L
= 50pF
70
70
From rising edge of
CS,
R
L
= 50Ω,
C
L
= 50pF
From rising edge of
CS,
R
L
= 50Ω,
C
L
= 50pF
0
480
240
240
190
190
100
0
85
120
2
2
1.0
1.0
2.1
µs
µs
MHz
ns
ns
ns
ns
ns
ns
ns
ns
µs
µs
ns
ns
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX4820/MAX4821
Note 1:
Specifications at -40°C are guaranteed by design and not production tested.
Note 2:
After relay turn-off, inductive kickback may momentarily cause the voltage at OUT_ to exceed V
COM
. This is considered part
of normal operation and will not damage the device.
_______________________________________________________________________________________
3
+3.3V/+5V, 8-Channel, Cascadable Relay Drivers
with Serial/Parallel Interface
MAX4820/MAX4821
Typical Operating Characteristics
(V
COM
= V
CC
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4820 toc01
SUPPLY CURRENT
vs. TEMPERATURE
V
CC
= 5V
20
SUPPLY CURRENT (µA)
V
CC
= 5.5V
MAX4820 toc02
SUPPLY CURRENT
vs. INPUT LOGIC VOLTAGE
900
800
SUPPLY CURRENT (µA)
700
600
500
400
300
200
100
V
CC
= 3.3V
V
CC
= 5V
ALL LOGIC INPUTS
CONNECTED
MAX4820 toc03
25
ALL LOGIC INPUTS = 0
20
SUPPLY CURRENT (µA)
25
1000
15
15
10
10
V
CC
= 3.3V
V
CC
= 2.3V
5
5
0
2.3
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
0
0
1
2
3
4
5
INPUT LOGIC VOLTAGE (V)
ON-RESISTANCE
vs. SUPPLY VOLTAGE
MAX4820 toc04
ON-RESISTANCE
vs. TEMPERATURE
I
OUT_SINK
= 70mA
2.5
2.0
R
ON
(Ω)
1.5
1.0
V
CC
= 5.5V
0.5
0
V
CC
= 5V
V
CC
= 2.3V
V
CC
= 3.3V
MAX4820 toc05
POWER-ON RESET VOLTAGE
vs. TEMPERATURE
1.75
POWER-ON RESET VOLTAGE (V)
1.50
1.25
1.00
0.75
0.50
0.25
0
-40
-15
10
35
60
85
MAX4820 toc06
3.0
I
OUT_SINK
= 70mA
2.5
2.0
R
ON
(Ω)
1.5
1.0
0.5
0
2.3
2.7
3.1
3.5
3.9
4.3
4.7
5.1
3.0
2.00
5.5
-40
-15
10
35
60
85
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT OFF-LEAKAGE CURRENT
vs. SUPPLY VOLTAGE
MAX4820 toc07
OUTPUT OFF-LEAKAGE CURRENT
vs. TEMPERATURE
MAX4820 toc08
OUT_ TURN-ON/TURN-OFF DELAY TIMES
vs. SUPPLY VOLTAGE
R
L
= 50Ω
C
L
= 50pF
MAX4820 toc09
1.0
0.9
OUTPUT OFF-LEAKAGE (nA)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2.3
2.7
3.1
3.5
3.9
4.3
4.7
5.1
2.00
1.75
OUTPUT OFF-LEAKAGE (nA)
1.50
1.25
1.00
0.75
0.50
0.25
0
V
CC
= 3.3V
-40
-15
10
35
60
V
CC
= 5V
V
CC
= 2.3V
V
CC
= 5.5V
80
70
t
ON
/t
OFF
DELAY TIME (ns)
60
50
t
OFF
40
30
20
t
ON
2.3
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
5.5
85
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
4
_______________________________________________________________________________________
3.3V/+5V, 8-Channel, Cascadable Relay Drivers
with Serial/Parallel Interface
Typical Operating Characteristics (continued)
(V
COM
= V
CC
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
INPUT LOGIC THRESHOLD
vs. SUPPLY VOLTAGE
2.25
INPUT LOGIC THRESHOLD (V)
2.00
1.75
1.50
1.25
1.00
0.75
0.50
2.3
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
200µs/div
SUPPLY VOLTAGE (V)
0
OUT_ TURNS OFF
V
CC
= 3.3V
OUT_
1V/div
MAX4820 toc10
MAX4820/MAX4821
BACK EMF CLAMPING
WITH STANDARD 3V RELAY
MAX4820 toc11
2.50
0
V
CS
5V/div
Pin Description
PIN
MAX4820
THIN
QFN
1
TSSOP
MAX4821
THIN
QFN
1
TSSOP
Reset Input. Drive
RESET
low to clear all latches and registers (all outputs
are turned off).
RESET
overrides all other inputs. If
RESET
and
SET
are pulled
low at the same time, then
RESET
takes precedence.
Chip-Select Input.
MAX4820:
Drive
CS
low to select the device. When
CS
is low, data at DIN is
clocked into the 8-bit shift register on SCLK’s rising edge. Drive
CS
from low
to high to latch the data to the registers and activate the appropriate relays.
MAX4821:
Drive
CS
low to select the device and set level on LVL. Drive
CS
from low to high to latch the address and level data to the output.
Serial Data Input
Serial Clock Input
Serial Data Output. DOUT is the output of the 8-bit shift register. This output
can be used to daisy chain multiple MAX4820s. The data at DOUT appears
synchronous to SCLK’s falling edge.
No Connection
Ground
Open-Drain Output 8. Connect OUT8 to the low side of a relay coil. This
output is pulled to PGND when activated, but otherwise is high impedance.
Open-Drain Output 7. Connect OUT7 to the low side of a relay coil. This
output is pulled to PGND when activated, but otherwise is high impedance.
Power Ground. PGND is a return for the output sinks. Connect PGND pins
together and to GND.
Open-Drain Output 6. Connect OUT6 to the low side of a relay coil. This
output is pulled to PGND when activated, but otherwise is high impedance.
NAME
FUNCTION
3
3
RESET
2
4
2
4
CS
3
4
5
6
7
8
9
10, 16
11
5
6
7
8
9
10
11
12, 18
13
—
—
—
—
7
8
9
10, 16
11
—
—
—
—
9
10
11
12, 18
13
DIN
SCLK
DOUT
N.C.
GND
OUT8
OUT7
PGND
OUT6
_______________________________________________________________________________________
5
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