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. Heslington