19-4770; Rev 1; 1/99 ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers The MAX6816/MAX6817/MAX6818 are single, dual, and octal switch debouncers that provide clean interfacing of mechanical switches to digital systems. They accept one or more bouncing inputs from a mechanical switch and produce a clean digital output after a short, preset qualification delay. Both the switch opening bounce and the switch closing bounce are removed. Robust switch inputs handle ±25V levels and are ±15kV ESDprotected for use in harsh industrial environments. They feature single-supply operation from +2.7V to +5.5V. Undervoltage lockout circuitry ensures the output is in the correct state upon power-up. The single MAX6816 and dual MAX6817 are offered in SOT packages and require no external components. Their low supply current makes them ideal for use in portable equipment. The MAX6818 octal switch debouncer is designed for data-bus interfacing. The MAX6818 monitors switches and provides a switch change-of-state output (CH), simplifying microprocessor (µP) polling and interrupts. Additionally, the MAX6818 has three-state outputs controlled by an enable (EN) pin, and is pin-compatible with the ‘LS573 octal latch (except for the CH pin), allowing easy interfacing to a digital data bus. Applications µP Switch Interfacing Industrial Instruments Features ♦ Robust Inputs can Exceed Power Supplies up to ±25V ♦ ESD Protection for Input Pins ±15kV—Human Body Model ±8kV—IEC 1000-4-2, Contact Discharge ±15kV—IEC 1000-4-2, Air-Gap Discharge ♦ Small SOT Packages (4 and 6 pins) ♦ Single-Supply Operation from +2.7V to +5.5V ♦ Single (MAX6816), Dual (MAX6817), and Octal (MAX6818) Versions Available ♦ No External Components Required ♦ 6µA Supply Current ♦ Three-State Outputs for Directly Interfacing Switches to µP Data Bus (MAX6818) ♦ Switch Change-of-State Output Simplifies Polling and Interrupts (MAX6818) ♦ Pin-Compatible with ’LS573 (MAX6818) Ordering Information PART TEMP. RANGE PINSOT PACKAGE TOP MARK MAX6816EUS-T -40°C to +85°C 4 SOT143 KABA MAX6817EUT-T -40°C to +85°C 6 SOT23-6 AAAU MAX6818EAP -40°C to +85°C 20 SSOP — Note: There is a minimum order increment of 2500 pieces for SOT packages. PC-Based Instruments Portable Instruments Automotive Applications Membrane Keypads Pin Configurations Typical Operating Circuit TOP VIEW VCC GND 4 VCC 3 OUT MAX6816 MAX6816 MECHANICAL SWITCH 1 µP 0.1µF IN OUT GND DEBOUNCED OUTPUT RESET IN 2 SOT143 Pin Configurations continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX6816/MAX6817/MAX6818 General Description MAX6816/MAX6817/MAX6818 ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70°C) 4-Pin SOT143 (derate 4.0mW/°C above +70°C)..........320mW 6-Pin SOT23 (derate 8.7mW/°C above +70°C)............691mW 20-Pin SSOP (derate 8.0mW/°C above +70°C) ...........640mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C Voltage (with respect to GND) VCC .......................................................................-0.3V to +6V IN_ (Switch Inputs) ..............................................-30V to +30V EN.........................................................................-0.3V to +6V OUT_, CH ...............................................-0.3V to (VCC + 0.3V) OUT Short-Circuit Duration (One or Two Outputs to GND)....................................Continuous 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 (VCC = +2.7V to +5.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = +5V, TA = +25°C.) (Note 1) PARAMETER SYMBOL Operating Voltage Range VCC Supply Current ICC Debounce Duration tDP CONDITIONS MIN TYP 2.7 VCC = 5V, IOUT = 0, IN_ = VCC VIH 5.5 V 20 µA MAX6818 20 40 60 MAX6816/MAX6817 20 50 80 VCC = 5V 2.4 VCC = 2.7V 2.0 0.8 Input Hysteresis 32 IN Input Current IIN Input Voltage Range VIN EN Pulse Width -25 1.9 VOL ISINK = 1.6mA VOH ISOURCE = 0.4mA tEN EN Threshold EN Input Current IIL EN Low to Out Active Propagation Delay tPE EN High to Out Three-State Propagation Delay EN Low to CH Out High Propagation Delay OUT_ Three-State Leakage Current 63 VIN = ±15V Undervoltage-Lockout Threshold ms V V 300 Input Pull-Up Resistance OUT_, CH Output Voltage UNITS 6 VIL Input Threshold MAX mV 100 kΩ ±1 mA 25 V 2.6 V 0.4 VCC - 1.0 200 V ns VCC = 5V 0.8 1.7 2.4 VCC = 2.7V 0.8 1.1 2.0 V ±1 µA RL = 10kΩ, CL = 100pF 100 ns tPD RL = 1kΩ, CL = 15pF 100 ns tPC RL = 10kΩ, CL = 50pF 100 ns VOUT = 0 or VCC ±10 µA ESD CHARACTERISTICS ESD Protection IN_ IEC1000-4-2 Air Discharge ±15 IEC1000-4-2 Contact Discharge ±8 Human Body Model ±15 Note 1: MAX6816 and MAX6817 production testing is done at TA = +25°C; over-temperature limits are guaranteed by design. 2 _______________________________________________________________________________________ kV ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers DEBOUNCE OF CLOSING SWITCH MAX6816 TOC03 MAX6816 TOC01 VCC = 5V 6 VCC = 3V 2 1 5V -5V -5V 4V 4V OUT (2V/div) 3 0 OUT (2V/div) IN (5V/div) 4 IN (5V/div) 5V 5 VCC = 5V 0 VCC = 5V 0 -25 0 25 50 75 10ms/div 100 10ms/div TEMPERATURE (°C) MAX6818 EN INPUT LOGIC THRESHOLD vs. SUPPLY VOLTAGE OUTPUT LOGIC LEVEL vs. SUPPLY VOLTAGE VOH, ISOURCE = 0.4mA 4 LOGIC THRESHOLD (V) 5 4 3 2 MAX6816 toc05 5 MAX6816 toc04 6 OUTPUT LOGIC LEVEL (V) 3 2 1 1 VOL, ISINK = 1.6mA 0 0 2 3 4 5 2 6 3 4 5 6 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) DEBOUNCE DELAY PERIOD vs. TEMPERATURE VCC UNDERVOLTAGE LOCKOUT vs. TEMPERATURE 45 VCC = 3V 40 VCC = 5V 35 MAX6816 toc07 5 VCC UNDERVOLTAGE LOCKOUT (V) 50 MAX6816 toc06 -50 DEBOUNCE DELAY PERIOD (ms) SUPPLY CURRENT (µA) DEBOUNCE OF OPENING SWITCH MAX6816 TOC02 SUPPLY CURRENT vs. TEMPERATURE 7 4 3 2 1 0 30 -50 -25 0 25 50 TEMPERATURE (°C) 75 100 -50 -25 0 25 50 75 100 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX6816/MAX6817/MAX6818 Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers MAX6816/MAX6817/MAX6818 Pin Description PIN NAME FUNCTION MAX6816 MAX6817 MAX6818 1 2 10 GND 2 — — IN Switch Input — 1, 3 — IN1, IN2 Switch Inputs — — 2–9 IN1–IN8 Switch Inputs 3 — — OUT CMOS Debounced Output — 4, 6 — OUT2, OUT1 CMOS Debounced Outputs — — 12–19 OUT8–OUT1 CMOS Debounced Outputs 4 5 20 VCC +2.7V to +5.5V Supply Voltage — — 1 EN Active-Low, Three-State Enable Input for outputs. Resets CH. Tie to GND to “always enable” outputs. — — 11 CH Change-of-State Output. Goes low on switch input change of state. Resets on EN. Leave unconnected if not used. Ground D VCC VCC D VCC OSC. COUNTER Q Q OUT LOAD R RPU UNDERVOLTAGE LOCKOUT IN ESD PROTECTION MAX6816 MAX6817 MAX6818 Figure 1. Block Diagram _______________Detailed Description Theory of Operation The MAX6816/MAX6817/MAX6818 are designed to eliminate the extraneous level changes that result from interfacing with mechanical switches (switch bounce). Virtually all mechanical switches bounce upon opening or closing. These switch debouncers remove bounce when a switch opens or closes by requiring that sequentially clocked inputs remain in the same state for a number of sampling periods. The output does not change until the input is stable for a duration of 40ms. The circuit block diagram (Figure 1) shows the functional blocks consisting of an on-chip oscillator, counter, exclusive-NOR gate, and D flip-flop. When the 4 input does not equal the output, the XNOR gate issues a counter reset. When the switch input state is stable for the full qualification period, the counter clocks the flip-flop, updating the output. Figure 2 shows the typical opening and closing switch debounce operation. On the MAX6818, the change output (CH) is updated simultaneously with the switch outputs. Undervoltage Lockout The undervoltage lockout circuitry ensures that the outputs are at the correct state on power-up. While the supply voltage is below the undervoltage threshold (typically 1.9V), the debounce circuitry remains transparent. Switch states are present at the logic outputs without delay. _______________________________________________________________________________________ ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers EN tEN IN1 1/2 VCC 1/2 VCC tPE OUT1–OUT8 OUT1 1/2 VCC tPE OUT1–OUT8 IN2 tPD OUT NORMALLY LOW VOL + 0.5V 1/2 VCC OUT NORMALLY VOH - 0.5V HIGH tPC CH OUT2 MAX6816/MAX6817/MAX6818 tDP tPD 1/2 VCC Figure 4. MAX6818 µP-Interface Timing Diagram CH +VCC MAX6818 ONLY +VCC 0.1µF Figure 2. Input Characteristics SW1 IN1 20V IN (20V/div) EN I/O CH IRQ OUT1 D0 OUT8 D7 µP MAX6818 0 -20V IN8 SW8 4V OUT (2V/div) Figure 5. MAX6818 Typical µP Interfacing Circuit 0 20ms/div Figure 3. Switch Input ±25V Fault Tolerance Robust Switch Inputs The switch inputs on the MAX6816/MAX6817/MAX6818 have overvoltage clamping diodes to protect against damaging fault conditions. Switch input voltages can safely swing ±25V to ground (Figure 3). Proprietary ESD-protection structures protect against high ESD encountered in harsh industrial environments, membrane keypads, and portable applications. They are designed to withstand ±15kV per the IEC1000-4-2 Air Gap Discharge Test and ±8kV per the IEC1000-4-2 Contact Discharge Test. Since there are 63kΩ (typical) pull-up resistors connected to each input, driving an input to -25V will draw approximately 0.5mA (up to 4mA for eight inputs) from the VCC supply. Driving an input to +25V will cause approximately 0.32mA of current (up to 2.6mA for eight inputs) to flow back into the VCC supply. If the total system VCC supply current is less than the current flowing back into the VCC supply, VCC will rise above normal levels. In some low-current systems, a zener diode on VCC may be required. ±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The MAX6816/MAX6817/MAX6818 have extra protection against static electricity. Maxim's engineers have developed state-of-the-art structures to protect against ESD of ±15kV at the switch inputs without _______________________________________________________________________________________ 5 RC 1M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF RD 1500Ω RC 50M to 100M DISCHARGE RESISTANCE CHARGE CURRENT LIMIT RESISTOR DEVICE UNDER TEST STORAGE CAPACITOR Figure 6a. Human Body ESD Test Model HIGHVOLTAGE DC SOURCE Cs 150pF RD 330Ω DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST Figure 7a. IEC1000-4-2 ESD Test Model I IP 100% 90% Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) 100% 90% AMPERES 36.8% I PEAK MAX6816/MAX6817/MAX6818 ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers 10% 0 0 tRL TIME tDL CURRENT WAVEFORM 10% Figure 6b. Human Body Current Waveform t r = 0.7ns to 1ns damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, the MAX6816/MAX6817/ MAX6818 keep working without latchup, whereas other solutions can latch and must be powered down to remove latchup. ESD protection can be tested in various ways; these products are characterized for protection to the following limits: 1) ±15kV using the Human Body Model 2) ±8kV using the Contact-Discharge method specified in IEC1000-4-2 3) ±15kV using IEC1000-4-2’s Air-Gap method. ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results. 6 t 30ns 60ns Figure 7b. IEC1000-4-2 ESD Generator Current Waveform Human Body Model Figure 6a shows the Human Body Model and Figure 6b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. IEC1000-4-2 The IEC1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The MAX6816/ MAX6817/MAX6818 help you design equipment that _______________________________________________________________________________________ ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers The major difference between tests done using the Human Body Model and IEC1000-4-2 is higher peak current in IEC1000-4-2, because series resistance is lower in the IEC1000-4-2 model. Hence, the ESD withstand voltage measured to IEC1000-4-2 is generally lower than that measured using the Human Body Model. Figure 7a shows the IEC1000-4-2 model and Figure 7b shows the current waveform for the 8kV, IEC1000-4-2, Level 4, ESD Contact-Discharge test. The Air-Gap test involves approaching the device with a charged probe. The Contact-Discharge method connects the probe to the device before the probe is energized. Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. MAX6818 µP Interfacing The MAX6818 has an output enable (EN) input that allows switch outputs to be three-stated on the µP data bus until polled by the µP. Also, state changes at the switch inputs are detected, and an output (CH) goes low after the debounce period to signal the µP. Figure 4 shows the timing diagram for enabling outputs and reading data. If the output enable is not used, tie EN to GND to “always enable’’ the switch outputs. If EN is low, CH is always high. If a change of state is not required, leave CH unconnected. Pin Configurations (continued) TOP VIEW IN1 1 GND 2 6 MAX6817 IN2 3 SOT23-6 OUT1 EN 1 20 VCC IN1 2 19 OUT1 IN2 3 18 OUT2 IN3 4 IN4 5 5 VCC 4 OUT2 17 OUT3 MAX6818 16 OUT4 IN5 6 15 OUT5 IN6 7 14 OUT6 IN7 8 13 OUT7 IN8 9 12 OUT8 GND 10 11 CH SSOP ___________________Chip Information MAX6816 TRANSISTOR COUNT: 284 MAX6817 TRANSISTOR COUNT: 497 MAX6818 TRANSISTOR COUNT: 2130 SUBSTRATE CONNECTED TO GND _______________________________________________________________________________________ 7 MAX6816/MAX6817/MAX6818 meets Level 4 (the highest level) of IEC1000-4-2, without the need for additional ESD-protection components. ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers SOT1434.EPS MAX6816/MAX6817/MAX6818 Package Information 8 _______________________________________________________________________________________ ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers 6LSOT.EPS _______________________________________________________________________________________ 9 MAX6816/MAX6817/MAX6818 Package Information (continued) ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers SSOP.EPS MAX6816/MAX6817/MAX6818 Package Information (continued) 10 ______________________________________________________________________________________ ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers MAX6816/MAX6817/MAX6818 NOTES ______________________________________________________________________________________ 11 MAX6816/MAX6817/MAX6818 ±15kV ESD-Protected, Single/Dual/Octal, CMOS Switch Debouncers NOTES 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. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.