Maxim MAX4896ATP+ Space-saving, 8-channel relay/load driver Datasheet

19-3843; Rev 1; 6/07
Space-Saving, 8-Channel Relay/Load Driver
Features
The MAX4896 8-channel relay and load driver is
designed for medium voltage applications up to 50V.
This device is offered in a 20-pin, 5mm x 5mm TQFN
package, resulting in substantial board space savings.
The MAX4896 8-channel relay driver offers built-in
inductive kickback protection, drive for latching/
nonlatching or dual-coil relays, and open-load and
short-circuit fault detection.The MAX4896 also protects
against overcurrent conditions. Each independent
open-drain output features a 3Ω (typ) on-resistance,
and is guaranteed to sink 200mA of load current
(VS ≥ 4.5V).
A built-in overvoltage protection clamp handles kickback-voltage transients, which are common when driving inductive loads. Thermal-shutdown circuitry shuts
off all outputs (OUT_) when the junction temperature
exceeds +160°C. The MAX4896 employs a reset input
that allows the user to turn off all outputs simultaneously
with a single control line.
♦ Supports Up to 50V Continuous Drain-to-Source
Voltage
♦ Guaranteed Drive Current:
♦ VS ≥ 4.5V
200mA (All Channels On)
410mA (Individual Channels)
♦ VS ≤ 3.6V
100mA
♦ Built-In Output Clamp Protects Against Inductive
Kickback
♦ +2.7V to +5.5V Logic Supply Voltage
♦ RESET Input Turns Off All Outputs
Simultaneously
♦ Built-in Power-On Reset
♦ Automotive Temperature Range
(-40°C to +125°C)
♦ SPI-/QSPI-/MICROWIRE-Compatible Serial
Interface
♦ Serial Digital Output for Daisy Chaining and
Diagnostics
♦ FLAG Output for µP Interrupt
♦ Open-Load and Short-Circuit Detection and
Protection
♦ Thermal Shutdown
♦ Low 100µA (max) Quiescent Supply Current
♦ Space-Saving, 5mm x 5mm, 20-Pin TQFN Package
The MAX4896 includes a 10MHz SPI™-/QSPI™-/
MICROWIRE™-compatible serial interface. The serial
interface is compatible with TTL-/CMOS-logic voltage
levels and operates with a single +2.7V to +5.5V supply. In addition, the SPI output data can be used for
diagnostics purposes including open-load and shortcircuit fault detection.
The MAX4896 is offered in the extended (-40°C to
+85°C) and automotive (-40°C to +125°C) operating
temperature ranges.
Typical Operating Circuit
Vcc = 2.7V TO 5.5V
VRELAY
0.1μF
PDCD
INT
Industrial Equipment
White Goods
RELAY
COIL 1
Ordering Information
OUT1
FLAG
VRELAY
PART
TEMP
RANGE
PINPACKAGE
MAX4896ETP+
-40°C to
+85°C
20 TQFN-EP*
(5mm x 5mm)
T2055-5
MAX4896ATP+
-40°C to
+125°C
20 TQFN-EP*
(5mm x 5mm)
T2055-5
SCLK
CS
MAX4896
RELAY
COIL 8
DIN
DOUT
SLPD
Automotive Relay Control
ATE
Power-Grid Monitoring
and Protection Equipment
VS
RESET
μC
Applications
OUT8
GND
PGND
PACKAGE
CODE
*EP = Exposed paddle
+ Denotes a lead-free package.
SPI and QSPI are trademarks of Motorola, Inc.
Pin Configuration appears at end of data sheet.
MICROWIRE is a trademark of National Semiconductor Corp.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX4896
General Description
MAX4896
Space-Saving, 8-Channel Relay/Load Driver
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.)
VS ......................................................................... -0.3V to +7.0V
OUT_ ....................................................................(-0.3V to +50V)
Continuous OUT_ Voltage ...................................................+50V
CS, SCLK, DIN, RESET, SPLD, PDCD ..................-0.3V to +7.0V
DOUT ............................................................-0.3V to (VS + 0.3V)
PGND to GND……………………………………..(-0.3V to +0.3V)
Continuous OUT_ Current, TA = +25°C (Note 1)
All Outputs On..................................................................210mA
Single Output On .............................................................420mA
Continuous Power Dissipation (TA = +70°C)
20-Pin TQFN (derate 21.3mW/°C above +70°C) ......1702mW
θJA ................................................................................+47°C/W
Maximum Output Clamp Energy (EOUT_) ...........................30mJ
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 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.
Note 1: Maximum continuous current at a given temperature must be calculated such that the maximum continuous power
dissipation for the package is not exceeded.
ELECTRICAL CHARACTERISTICS
(VS = +2.7V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
Operating Voltage
VS
Quiescent Current
ICC
Dynamic Average Supply
Current
Thermal Shutdown
Thermal-Shutdown Hysteresis
IS
CONDITIONS
MIN
TYP
2.7
IOUT_ = 0, logic inputs = VS = 3.6V
0 or VS, RESET = low
VS = 5V
MAX
UNITS
5.5
V
5
70
10
100
fSCLK = 10MHz, fDIN = 0.5 x fCLK,
COUT = 50pF, VS = 5.5V
6
µA
mA
TSHD
+160
°C
TSHDH
20
°C
Power-On Reset
VRST
Power-On-Reset Hysteresis
VRSTH
VS falling
1.8
2.05
2.3
140
V
mV
DIGITAL INPUTS (SCLK, DIN, CS, RESET, PDCD, SPLD)
Input Logic-High Voltage
Input Logic-Low Voltage
VIH
VIL
Input Logic Hysteresis
VHYST
Input Leakage Currents
ILEAK
Input Capacitance
VS = 2.7V to 3.6V
2.0
VS = 4.5V to 5.5V
2.4
V
VS = 2.7V to 3.6V
0.6
VS = 4.5V to 5.5V
0.8
V
230
Input voltages = 0 or +5.5V
-1
CIN
mV
+1
10
µA
pF
RELAY OUTPUT DRIVERS (OUT1–OUT8)
IOUT = 50mA,
VS = 2.7V
OUT_ ON Resistance
RON
IOUT = 100mA,
VS = 4.5V
IOUT Off-Leakage Current
2
ILEAK
TJ = +25°C
5
TJ = +125°C
TJ = +150°C
12
TJ = +25°C
3
TJ = +125°C
TJ = +150°C
PDCD = high or RESET = low, all outputs
off
6
11
4
Ω
7
8
-1
_______________________________________________________________________________________
+1
µA
Space-Saving, 8-Channel Relay/Load Driver
MAX4896
ELECTRICAL CHARACTERISTICS (continued)
(VS = +2.7V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
PARAMETER
OUT Clamping Voltage
SYMBOL
VCLAMP
OUT Current-Limit Threshold
ILIM
OUT Capacitance
CONDITIONS
MIN
(Note 3)
50
VS ≥ 4.5V
400
VOUT = 16V, f = 1MHz
TYP
MAX
UNITS
75
V
960
mA
30
pF
DIAGNOSTIC
Open-Load Detection Voltage
Threshold
VDS(OL)
Open-Load Detection-VoltageThreshold Hysteresis
VDS(OLH)
OUT_ Pulldown Current
Fault Delay/Filtering Time
IPD(OL)
tD(FAULT)
OUT_ falling
0.75
1
1.15
40
V
mV
PDCD = low
150
300
500
µA
From rising edge at CS at 50% to valid
diagnostic data
30
90
280
µs
DIGITAL OUTPUT (DOUT, FLAG)
DOUT Low Voltage
VOL
DOUT High Voltage
VOH
2.7V ≤ VS ≤ 3.6V, ISINK = 0.3mA
0.4
4.5V ≤ VS ≤ 5.5V, ISINK = 0.5mA
0.4
2.7V ≤ VS ≤ 3.6V, ISOURCE = 0.25mA
4.5V ≤ VS ≤ 5.5V, ISOURCE = 0.4mA
FLAG Low Voltage
ISINK = 0.5mA
FLAG Off-Leakage Current
4.5V ≤ VS ≤ 5.5V, VFLAG = 5.5V
VS - 0.5
V
VS - 0.5
-1
V
0.4
V
+1
µA
TIMING
Turn-On Time (OUT_)
Turn-Off Time (OUT_)
tON
tOFF
From rising edge of CS at 50% to VOUT_
= 90%VP, VP = 15V, RL = 300Ω,
CL = 50pF, 2.7V ≤ VS < 3.6V
20
From rising edge of CS at 50% to VOUT_
= 90%VP, VP =16V, RL = 150Ω,
CL = 50pF, 4.5V ≤ VS ≤ 5.5V
10
From rising edge of CS at 50% to VOUT_
= 10%VP, VP = 15V, RL = 300Ω,
CL = 50pF, 2.7V ≤ VS < 3.6V
15
From rising edge of CS at 50% to VOUT_
= 90%VP, VP = 16V, RL = 150Ω,
CL = 50pF, 4.5V < VS ≤ 5.5V
10
µs
µs
_______________________________________________________________________________________
3
MAX4896
Space-Saving, 8-Channel Relay/Load Driver
ELECTRICAL CHARACTERISTICS (continued)
(VS = +2.7V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
TA = +85°C
SCLK Frequency
fSCLK
TA = +125°C
Cycle Time
tCH + tCL
CS Fall-to-SCLK Rise Setup
tCSS
CS Rise-to-SCLK Hold
tCSH
SCLK High Time
tCH
SCLK Low Time
tCL
Data Setup Time
tDS
Data Hold Time
tDH
SCLK Fall-to-DOUT Valid
tDO
Rise Time (DIN, SCLK, CS,
RESET)
tSCR
Fall Time (DIN, SCLK, CS,
RESET)
tSCF
RESET Min Pulse Width
tRW
2.7V ≤ VS < 3.6V
MIN
4.5V ≤ VS ≤ 5.5V
2.7V ≤ VS ≤ 3.6V
0
4.5V ≤ VS ≤ 5.5V
4.5V ≤ VS ≤ 5.5V
100
2.7V ≤ VS ≤ 3.6V
100
4.5V ≤ VS ≤ 5.5V
50
2.7V ≤ VS ≤ 3.6V
100
4.5V ≤ VS ≤ 5.5V
50
2.7V ≤ VS ≤ 3.6V
80
4.5V ≤ VS ≤ 5.5V
40
2.7V ≤ VS ≤ 3.6V
80
4.5V ≤ VS ≤ 5.5V
40
2.7V ≤ VS ≤ 3.6V
40
4.5V ≤ VS ≤ 5.5V
20
2.7V ≤ VS ≤ 3.6V
5
4.5V ≤ VS ≤ 5.5V
0
20% of VS to 70%
of VS, CL = 50pF
(Note 4)
UNITS
6
5
MHz
10
200
20% of VS to 70%
of VS, CL = 50pF
(Note 4)
MAX
11
2.7V ≤ VS ≤ 3.6V
50% of SCLK to
20% of VS falling
edge, CL = 50pF,
50% at SCLK to
80% of VS rising
edge
TYP
0
2.7V ≤ VS ≤ 3.6V
ns
ns
ns
ns
ns
ns
ns
70
ns
4.5V ≤ VS ≤ 5.5V
30
2.7V ≤ VS ≤ 3.6V
2
4.5V ≤ VS ≤ 5.5V
2
2.7V ≤ VS ≤ 3.6V
2
4.5V ≤ VS ≤ 5.5V
2
µs
µs
70
ns
Note 2: Specifications at -40°C are guaranteed by design and not production tested.
Note 3: The output stages are compliant with the transient immunity requirements, as specified in ISO 7637 Part 3 with test pulses 1,
2, 3a, and 3b.
Note 4: Guaranteed by design.
4
_______________________________________________________________________________________
Space-Saving, 8-Channel Relay/Load Driver
(TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. fCLK
6
5
4
TA = +85°C
TA = +25°C
3
2
1
0
VS = 5V
4.0
VS = 3.3V
3.0
2.5
4.3
4.7
5.1
5.5
2.0
0.1
1
7
IOUT_SINK = 100mA
7
VS = 2.7V
RON (Ω)
VS = 3.3V
4
VS = 5V
VS = 3.3V
5
4
VS = 5V
3
VS = 5.5V
3
VS = 5.5V
2
1
3.9
4.3
4.7
5.1
2.14
6
VS = 2.7V
3.5
5.5
POWER-ON RESET VOLTAGE
vs. TEMPERATURE
8
MAX4896 toc04
IOUT_SINK = 50mA
2
3.1
SUPPLY VOLTAGE (V)
ON-RESISTANCE
vs. TEMPERATURE
8
5
2.7
10
fCLK (MHz)
ON-RESISTANCE
vs. TEMPERATURE
6
IOUT_SINK = 50mA
2.5
VS = 2.7V
POWER-ON-RESET VOLTAGE (V)
3.9
4.5
3.5
3.0
MAX4896 toc05
3.5
IOUT_SINK = 100mA
5.0
4.0
3.5
2.0
3.1
MAX4896 toc 03
5.5
4.5
SUPPLY VOLTAGE (V)
2.12
2.10
2.08
2.06
2.04
2.02
1
2.00
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT OFF LEAKAGE CURRENT
vs. SUPPLY VOLTAGE
70
60
VOUT = 50V
50
VOUT = 24V
40
30
VOUT = 12V
20
PDCD = VS
10
1
0.1
0.01
VOUT = 50V
VOUT = 24V
VOUT = 12V
2.50
MAX4896 toc09
80
100
MAX4896 DS toc08
90
OUT LEAKAGE CURRENT (nA)
MAX4896 toc07
100
INPUT LOGIC THRESHOLD
vs. SUPPLY VOLTAGE
OUT LEAKAGE CURRENT
vs. TEMPERATURE
2.25
INPUT LOGIC THRESHOLD (V)
RON (Ω)
6.0
5.0
TA = -40°C
2.7
OUTPUT OFF LEAKAGE (pA)
6.5
MAX4896 DS toc06
TA = +125°C
fDIN = 0.5 x fCLK
RON (Ω)
8
7
5.5
7.0
MAX4896 toc02
ALL LOGIC INPUTS = VS
ON-RESISTANCE
vs. SUPPLY VOLTAGE
6.0
MAX4896 toc01
12
11
10
9
SUPPLY CURRENT (mA)
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT
vs. SUPPLY VOLTAGE
2.00
1.75
1.50
1.25
1.00
0.75
10
0.001
0
2.7
3.1
3.5
3.9
4.3
4.7
SUPPLY VOLTAGE (V)
5.1
5.5
0.50
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
MAX4896
Typical Operating Characteristics
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
2.0
tOFF
1.5
1.0
tON
CL = 50pF
4.0
3.5
3.0
2.5
2.0
tOFF
1.5
1.0
0.5
800
2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6
650
TA = +85°C
600
550
TA = +125°C
500
400
0
0
TA = +25°C
700
450
tON
0.5
TA = -40°C
750
4.5
4.7
4.9
5.1
5.3
4.5
5.5
4.7
4.9
5.1
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
OUT CLAMP VOLTAGE
vs. TEMPERATURE
BACK-EMF CLAMPING
WITH STANDARD +12V RELAY
BACK-EMF CLAMPING
WITH STANDARD +24V RELAY
MAX4896 toc13
65.8
65.6
VS = 5V
RESET
5V/div
RESET
(2V/div)
65.4
5.5
MAX4896 toc15
MAX4896 toc14
VS = 3.3V
65.2
65.0
64.8
64.6
64.4
OUT
(20V/div)
OUT
(20V/div)
64.2
64.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
1ms/div
TEMPERATURE (°C)
6
5.3
SUPPLY VOLTAGE (V)
66.0
MAX4896 toc12
4.5
MAX4896 toc11
RL = 150Ω
VOUT = 50V
OUTPUT CURRENT LIMIT (mA)
tON/tOFF DELAY TIME (μs)
2.5
5.0
tON/tOFF DELAY TIME (μs)
RL = 300Ω
CL = 50pF
VOUT = 15V
MAX4896 toc10
3.0
OUT_ CURRENT LIMIT
vs. SUPPLY VOLATGE
TURN-ON/TURN-OFF DELAY TIME
vs. SUPPLY VOLTAGE
TURN-ON/TURN-OFF DELAY TIME
vs. SUPPLY VOLTAGE
0UT CLAMP VOLTAGE (V)
MAX4896
Space-Saving, 8-Channel Relay/Load Driver
_______________________________________________________________________________________
1ms/div
Space-Saving, 8-Channel Relay/Load Driver
PIN
NAME
1
RESET
2
CS
Chip Select Input. 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.
3
DIN
Serial Data Input
4
SCLK
Serial Clock Input
5
DOUT
Serial Data Output. DOUT is the output of the 8-bit shift register. This output can be used to daisy
chain multiple MAX4896s. The data at DOUT appears synchronous to SCLK’s falling edge.
6
PDCD
Pulldown Current Disable. Drive PDCD high to disable OUT’s pulldown current source. Drive PDCD
low to enable OUT_ pulldown current source. PDCD must be low to detect an open-load fault.
7
SPLD
Short-Protection Latch-Off Disable Input. Drive SPLD high to disable the built-in short-circuit
protection latch-off feature. When SPLD is low, an overloaded channel is turned off immediately. See
the Output Short-Circuit/Current-Limiting Protection section.
8
OUT8
Open-Drain Output 8. Connect OUT8 to the low side of a relay coil. OUT8 is pulled to PGND when
activated and is otherwise high impedance.
9
OUT7
Open-Drain Output 7. Connect OUT7 to the low side of a relay coil. OUT7 is pulled to PGND when
activated and is otherwise high impedance.
10, 16
PGND
Power Ground. PGND is the ground return path for the output sinks. Connect PGND pins together
and to GND.
11
OUT6
Open-Drain Output 6. Connect OUT6 to the low side of a relay coil. OUT6 is pulled to PGND when
activated and is otherwise high impedance.
12
OUT5
Open-Drain Output 5. Connect OUT5 to the low side of a relay coil. OUT5 is pulled to PGND when
activated and is otherwise high impedance.
13
GND
Ground
14
OUT4
Open-Drain Output 4. Connect OUT4 to the low side of a relay coil. OUT4 is pulled to PGND when
activated and is otherwise high impedance.
15
OUT3
Open-Drain Output 3. Connect OUT3 to the low side of a relay coil. OUT3 is pulled to PGND when
activated and is otherwise high impedance.
17
OUT2
Open-Drain Output 2. Connect OUT2 to the low side of a relay coil. OUT2 is pulled to PGND when
activated and is otherwise high impedance.
18
OUT1
Open-Drain Output 1. Connect OUT1 to the low side of a relay coil. OUT1 is pulled to PGND when
activated and is otherwise high impedance.
19
VS
20
FLAG
—
EP
FUNCTION
Reset Input. Drive RESET low to clear all latches and registers (all outputs are turned off). All OUT
pulldown currents are disabled when RESET = low.
Input Supply Voltage. Bypass VS to GND with a 0.1µF capacitor.
Open-Drain Fault Output. FLAG asserts low when a fault occurs at OUT1–OUT8.
Exposed Paddle. Connect EP to ground plane.
_______________________________________________________________________________________
Heslington
7
MAX4896
Pin Description
MAX4896
Space-Saving, 8-Channel Relay/Load Driver
Detail Description
The MAX4896 is an 8-channel relay and load driver for
medium voltage applications up to 50V. The MAX4896
features built-in inductive kickback protection, drive for
latching/nonlatching, or dual-coil relays and an internal
register for detecting open-load and short-circuit faults.
Each independent open-drain output features a 3Ω onresistance and is guaranteed to sink 400mA at VS ≥
4.5V, and 100mA at VS ≤ 3.6V.
The MAX4896 also incorporates a logic input (PDCD)
that allows the device to continue operating when an
overcurrent condition lasts longer than the 280µs (max)
fault delay time. A built-in overvoltage protection clamp
handles kickback voltage transients, which are common when driving inductive loads. Thermal-shutdown
circuitry shuts off all outputs (OUT_) when the junction
temperature exceeds +160°C.
The MAX4896 employs a reset input that allows the
user to turn off all outputs simultaneously with a single
control line.
The MAX4896 includes a 10MHz SPI-/QSPI-/MICROWIREcompatible serial interface. The serial interface is compatible with TTL-/CMOS-logic voltage levels and operates
with a single +2.7V to +5.5V supply.
Serial Interface
The serial interface consists of an 8-bit input shift register, a parallel latch (output control register) controlled
by SCLK and CS, and an output status register containing diagnostics information. The input to the shift register is an 8-bit word. Each data bit controls one of the
eight outputs, with the most significant bit (D7) corresponding to OUT8, and the least significant bit (D0)
corresponding to OUT1 (see Table 1). When CS is low,
data at DIN is clocked into the shift register synchronously with SCLK’s rising edge. Driving CS from low to
OUTPUT STATUS REGISTER (OSR)
high latches the data in the shift register to the output
control register.
DOUT is the output of the internal output status register
for diagnostics purposes (see Figure 2 and Tables 2
and 3). Status data for each channel is transferred to
the shift register at the falling edge of CS. The data bits
contained in the shift register are then transferred to the
DOUT output synchronously with SCLK’s falling edge.
While CS is low, the switches always remain in their
previous states. Drive CS high after 8 bits of data have
been shifted in to update the output state, and to further
inhibit data from entering the shift register. When CS is
high, transitions at DIN and SCLK have no effect on the
output, and the first input bit (D7) is present at DOUT.
If the number of data bits entered while CS is low is
greater or less than 8, the shift register contains only
the last 8 data bits, regardless of when they were
entered.
The 3-wire serial interface is compatible with SPI, QSPI,
and MICROWIRE standards. The latch that drives the
analog output stages is updated on the rising edge of
CS, regardless of SCLK’s state.
Diagnostic Information
The MAX4896 contains an internal output status register used for diagnostics information for each output
(see Tables 1, 2, and 3). When a fault condition is
detected at any channel for longer than the minimum
fault-filtering time (tD(FAULT)_min), the fault information
is latched into the corresponding position in the output
status register (see Table 2), and the FLAG asserts.
Status/diagnostics data for each channel in the output
status register is transferred to the output shift register
at the falling edge of CS. While CS is low, the diagnostics bits are then transferred to DOUT synchronously
with SCLK’s falling edge. A rising edge at CS resets the
output status register data. During normal operation,
the output status bit is the same as the DIN bit (DO1 =
D1, DO2 = D2). When the MAX4896 is operating with a
fault condition, the output status bit is the inverse of the
DIN bit (DO1 = 0, D1 = 1).
LATCHED ON CS:
DIN
SCLK
8-BIT SHIFT REGISTER
DOUT
CS
LATCHED ON CS:
OUTPUT CONTROL REGISTER (OUT)
Figure 1. Serial Interface
8
_______________________________________________________________________________________
Space-Saving, 8-Channel Relay/Load Driver
DIN
OUT_
D0
D1
D2
D3
D4
D5
D6
D7
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
OUT7
OUT8
DO3
OUT4
DO4
OUT5
DO5
OUT6
DO6
OUT7
DO7
OUT8
MAX4896
Table 1. Serial-Input Address
Table 2. Serial-Output Address
DO0
OUT1
DOUT
OUT_
DO1
OUT2
DO2
OUT3
Table 3. Status-Register Output Diagnostic
OUTPUT
STATUS
Off
DO_
STATUS BIT
Low
Off
High
Fault condtion. Output open or
short circuit.
On
Low
Fault condition. Short circuit to
positive load voltage.
On
High
Normal operation.
DIAGNOSTIC
Normal operation.
CS
tCSW
tCL
tCSS
tCSO
tCSH
tCH
SCLK
tDH
tDS
DIN
D7
D6
D0
D1
tDO
DOUT
tON,
tOFF
OUT_
Figure 2. 3-Wire Serial-Interface Timing
_______________________________________________________________________________________
9
MAX4896
Space-Saving, 8-Channel Relay/Load Driver
The minimum fault-filtering time helps mask short-duration fault conditions, such as driving highly capacitive
loads.
The typical diagnostics software routine works as follows:
• Write data to the MAX4896
• Wait for tD(FAULT) maximum to ensure diagnostics
data is ready and valid
• Write same data to the MAX4896 and read out the
diagnostics data from the shift register
Use Table 3 to diagnose the output state.
To reduce processor overhead, an interrupt-based
diagnostics routine is possible. The diagnostics routine
will analyze diagnostics data only when the FLAG output triggers an interrupt.
Output Short-Circuit/Current-Limiting Protection
The MAX4896 channels (OUT_) are protected against
short-circuits conditions. When the channel’s output
current exceeds the current-limit threshold (ILIM) for
longer than the minimum fault-filtering time (tD(FAULT)
min), the short-circuit protection is activated. The shortcircuit protection behavior is determined by the logic
level at SPLD. When SPLD = high, an overloaded channel remains in a current-limited state until the short-circuit condition is removed or thermal shutdown is
reached. This allows the operation of loads where the
inrush currents may exceed the MAX4896 internal current limit.
When SPLD = low, an overloaded channel immediately
turns off (latched-off). When a shorted output is latched
off, the channel can be turned back on after the next
serial input data is latched into the MAX4896.
Open-Load Detection
The MAX4896 features an output pulldown current
source, along with a voltage comparator, to detect an
open-load fault condition. To enable the open-load
detection function, PDCD must be low. The voltage at
OUT_ is compared with the diagnostics threshold voltage (VDS(OL)) to determine whether a open-load fault
condition exists.
10
Thermal Shutdown
If the junction temperature exceeds +160°C, all outputs
are switched off immediately (no filtering time) and
FLAG asserts. The hysteresis is approximately +20°C,
disabling thermal shutdown once the temperature
drops below +140°C.
RESET
The MAX4896 features an asynchronous reset input
that allows the user to simultaneously turn all outputs off
using a single control line. Drive RESET low to clear all
latches and registers, and to turn off all outputs. While
RESET is low, the OUT pulldown currents are disabled,
regardless of the state of PDCD.
FLAG Output
FLAG is an open-drain latched output that can be connected to a µP interrupt and pulls low whenever a fault
condition (short-circuit and/or open-load) is detected in
any of the eight outputs for longer than the minimum
fault-filtering time (tD(FAULT) min). FLAG asserts immediately, (no filtering time), when a thermal-shutdown
fault condition is detected. The latch FLAG deasserts
on CS rising edge.
Applications Information
Daisy Chaining
The MAX4896 features a digital output (DOUT) that provides 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 multiple devices, connect all CS inputs together and connect the DOUT of one device to the DIN of another
device (see Figure 3). During operation, a stream of
serial data is shifted through all the MAX4896s in
series.
Inductive Kickback Protection
Each output features an output protection clamp, limiting the OUT voltage to 65V (typ). The clamp protects
against voltage transient when driving inductive loads.
______________________________________________________________________________________
Space-Saving, 8-Channel Relay/Load Driver
VS
0.1μF
DEVICE 1
DIN
VS
DIN
DOUT
MAX4896
SCLK
0.1μF
DEVICE 2
VS
DIN
MAX4896
VS
DOUT
MAX4896
OUT1
SCLK
SCLK
OUT8
CS
OUT1
GND
OUT8
CS
PGND
GND
PGND
CS
Figure 3. Daisy-Chain Configuration
Functional Diagram
VS
PDCD
SPLD
OUT1
CLAMP
GATE CONTROL
AND CURRENT
LIMITING
RESET
8-BIT
LATCH
OPEN / SHORT
DETECT
CHANNEL 1
SPI/CONTROL
INTERFACE
DIN
CHANNEL 2
OUT2
CHANNEL 3
OUT3
CHANNEL 4
OUT4
CHANNEL 5
OUT5
CHANNEL 6
OUT6
CHANNEL 7
OUT7
CHANNEL 8
OUT8
DOUT
SCLK
CS
OVERTEMPERATURE
PROTECTION
FLAG
MAX4896
GND
PGND
______________________________________________________________________________________
11
Pin Configuration
Chip Information
OUT4
GND
OUT5
OUT6
TOP VIEW
OUT3
PROCESS: BiCMOS
15
14
13
12
11
PGND 16
10
PGND
OUT2 17
9
OUT7
8
OUT8
7
SPLD
6
PDCD
OUT1 18
MAX4896
VS 19
1
2
3
4
5
DIN
SCLK
DOUT
+
CS
FLAG 20
*EP
RESET
MAX4896
Space-Saving, 8-Channel Relay/Load Driver
TQFN
5mm x 5mm
*EXPOSED PADDLE. CONNECT TO PGND.
12
______________________________________________________________________________________
Space-Saving, 8-Channel Relay/Load Driver
QFN THIN.EPS
____________________Revision History
Pages changed at Rev 1: 1, 12, 13, 14
______________________________________________________________________________________
13
MAX4896
Package Information
Space-Saving, 8-Channel Relay/Load Driver
MAX4896
Package Information (continued)
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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