On/Off Controller with Debounce and

Transcription

1 ; Rev ; 5/8 On/Off Controller with Debounce and General Description The is a pushbutton on/off controller with a single switch debouncer and built-in latch. It accepts a noisy input from a mechanical switch and produces a clean latched digital output after a factory-fixed qualification delay. The eliminates contact bounce during switch opening and closing. The state of the output changes only when triggered by the falling edge of the debounced switch input; the output remains unchanged on the rising edge of the input. Robust switch inputs handle ±25V levels and are ±15kV ESD protected for use in harsh industrial environments. The features a complementary output,, which is the inverted state of. An asynchronous input allows an external signal to force the output flip-flop low. Undervoltage-lockout circuitry ensures that is in the off state upon power-up. The requires no external components, and its low supply current makes it ideal for use in portable equipment. The operates from a +2.7V to +5.5V single supply. The is offered in a 6-pin thin SOT23 package and operates over the -4 C to +125 C automotive temperature range. PDAs MP3/Video Players Portable Electronics Set-Top Boxes Portable Instrumentation White Goods TOP VIEW 1 + Applications Pin Configuration 6 Features Robust Inputs Can Handle Power Supplies Up to ±25V Latched Output Low 7µA Supply Current Operates from 2.7V to 5.5V -4 C to +125 C Temperature Range Thin SOT23 Package Ordering Information PART TEMP RANGE P- PACKAGE 3V LDO EN TOP MARK AZT+T -4 C to +125 C 6 Thin SOT23 +AADU +Denotes a lead-free package. T = Tape and reel package. Devices are offered in 2.5k unit increments. Typical Operating Circuits μp ON/OFF WITH LDO TH SOT23 Typical Operating Circuits continued at end of data sheet. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim s website at

2 ABSOLUTE MAXIMUM RATGS to...-.3v to +6V to...-3v to +3V to...-.3v to +6V, to...-.3v to ( +.3V) Short-Circuit Duration, to...continuous Note 1: As per JEDEC 51 standard, multilayer board (PCB). 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 Continuous Power Dissipation (T A = +7 C) 6-Pin Thin SOT23 (derate 9.1mW/ C at +7 C) (Note 1)...727mW Operating Temperature Range...-4 C to +125 C Maximum Junction Temperature C Storage Temperature Range...-6 C to +15 C Lead Temperature (soldering, 1s)...+3 C ( = +2.7V to +5.5V, T A = T J = -4 C to +125 C, unless otherwise noted. Typical values are at = +5V, T A = +25 C.) (Note 2) PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS Operating Voltage Range (Note 3) V Supply Current I CC = 5V, I = I =, not connected 7 2 µa T A = +25 C Debounce Duration t DP T A = -4 C to +125 C ms Threshold V IL.65 = 5V 2.5 V IH = 2.7V 2. V Hysteresis 42 mv Pullup Resistance kω V = +25V +1.5 Current I V = -25V -1.5 Voltage Range V V Undervoltage-Lockout Threshold V UVLO falling V / Output Voltage Threshold V OL I SK = 1.6mA.4 V OH I SOURCE =.4mA - 1. V _IL.7 = 5V 2.4 V _IH VCC = 2.7V 2. Input Current I µa High to Low Propagation Delay ESD CHARACTERISTICS ESD Protection t CO R L = 1kΩ, C L = 1pF 2 ns IEC Air Discharge IEC Contact Discharge Note 2: All devices are 1% production tested at T A = +25 C. Specifications over temperature limits are guaranteed by design. Note 3: is guaranteed to be low for 1.V V UVLO. ±15 ±8 Human Body Model ±15 ma V V kv 2

3 (T A = +25 C, unless otherwise noted.) SUPPLY CURRENT (μa) SUPPLY CURRENT vs. TEMPERATURE = 5V = 3V TEMPERATURE ( C) toc1 DEBOUNCE OF CLOSG SWITCH = 5V 1ms/div Typical Operating Characteristics toc2 1V 1V/div -1V 5V/div V 5V/div V PUT LOGIC LEVEL (V) PUT LOGIC LEVEL vs. SUPPLY VOLTAGE V OH, I SOURCE =.4mA 1 V OL, I SK = 1.6mA SUPPLY VOLTAGE (V) toc3 DEBOUNCE DELAY PERIOD (ms) DEBOUNCE DELAY PERIOD vs. TEMPERATURE = 3V = 5V TEMPERATURE ( C) toc4 VCC UNDERVOLTAGE LOCK (V) UNDERVOLTAGE LOCK vs. TEMPERATURE.5 RISG TEMPERATURE ( C) toc5 Pin Description P NAME FUNCTION 1 Switch Toggle Input. features a -25V to +25V maximum input range and includes an internal 63kΩ pullup resistor to. Connect a pushbutton from to. 2 Ground 3 Clear Input. Pull high to force low. Connect to if unused. 4 Active-Low CMOS Output 5 Active-High CMOS Output V to +5.5V Supply Input. In noisy environments, bypass to with a.1µf or greater ceramic capacitor. 3

4 OSC D COUNTER R Q D CLR Q Functional Diagram Q T CLR R R PU ESD PROTECTION XNOR UNDERVOLTAGE LOCK Detailed Description Theory of Operation The creates a push-on, push-off function using a momentary-contact normally open SPST switch. The high-to-low transition that occurs when closing the switch causes to go high and to go low. The output state remains latched after the switch is released/opened. Closing the switch again causes to go low and to go high. Debounce circuitry eliminates the extraneous level changes that result from interfacing with mechanical switches (switch bounce). Virtually all mechanical switches bounce upon opening and closing. The bounce when a switch opens or closes is eliminated by requiring that the sequentially clocked input remains in the same state for a number of sampling periods. The output does not change state from high-to-low or lowto-high until the input is stable for at least 5ms (typ). The Functional Diagram shows the functional blocks consisting of an on-chip oscillator, counter, exclusive- NOR gate, a D flip-flop, and a T (toggle) flip-flop. When the pushbutton input does not equal the internal debounced button state (the Q output of the D flipflop), the XNOR gate issues a counter reset. When the switch input state is stable for the full qualification period, the counter clocks the D flip-flop, changing the internal pushbutton state. The Q output of the D flip-flop is connected to a toggle flip-flop that toggles when the internal pushbutton state goes through a high-to-low transition. Figure 1 shows the typical opening and closing switch debounce operation. A rising pulse at resets the T flip-flop and pulls low and high. 4

5 UVLO t DP t DP t DP t DP t DP PUT OF D FLIP-FLOP (VERTED AFTER DEBOUNCE) t CO Figure 1. Timing Diagram Undervoltage Lockout The undervoltage-lockout circuitry ensures that the outputs are at the correct state on power-up. While is less than the 2.1V (typ) undervoltage threshold and greater than 1.V, remains low and transitions at are ignored. Robust Switch Input The switch input () has overvoltage clamping diodes to protect against damaging fault conditions. Switch input voltages can safely swing ±25V to ground. 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 IEC Air-Gap Discharge test and ±8kV per the IEC Contact- Discharge test. Since there is a 63kΩ (typ) pullup resistor connected to, driving the input to -25V draws approximately.5ma from the supply. Driving the input to +25V causes approximately.32ma of current to flow back into the supply. If the total system supply current is less than the current flowing back into the supply, rises above normal levels. In some low-current systems, a zener diode on may be required. ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The has extra protection against static electricity to protect against ESD of ±15kV at the switch input without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. A design advantage of the is that it continues working without latchup after an ESD event, which eliminates the need to power-cycle the device. ESD protection can be tested in various ways; this product is characterized for protection to the following limits: 1) ±15kV using the Human Body Model. 2) ±8kV using the Contact-Discharge method specified in IEC ) ±15kV using the IEC Air-Gap method. 5

6 Human Body Model Figure 2a shows the Human Body Model, and Figure 2b shows the current waveform it generates when discharged into a low impedance. This model consists of a 1pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. IEC The IEC standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The helps in the design of equipment that meets IEC , without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC is higher peak current in IEC , because series resistance is lower in the IEC model. Hence, the ESD withstand voltage measured to IEC is generally lower than that measured using the Human Body Model. Figure 3a shows the IEC model, and Figure 3b shows the current waveform for the IEC 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 2pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. R C 1MΩ R D 15Ω R C 5MΩ to 1MΩ R D 33Ω CHARGE-CURRENT LIMIT RESISTOR DISCHARGE RESISTANCE CHARGE-CURRENT LIMIT RESISTOR DISCHARGE RESISTANCE HIGH- VOLTAGE DC SOURCE Cs 1pF STORAGE CAPACITOR DEVICE UNDER TEST HIGH- VOLTAGE DC SOURCE Cs 15pF STORAGE CAPACITOR DEVICE UNDER TEST Figure 2a. Human Body ESD Test Model Figure 3a. IEC ESD Test Model I I P 1% 9% Ir PEAK-TO-PEAK RGG (NOT DRAWN TO SCALE) 1% 9% AMPERES 36.8% IPEAK 1% t RL TIME t DL CURRENT WAVEFORM 1% Figure 2b. Human Body Current Waveform tr =.7ns TO 1ns 3ns t 6ns Figure 3b. IEC ESD Generator Current Waveform 6

7 3V μp Typical Operating Circuits (continued) ON/OFF WITH p-channel MOSFET PUSH EITHER BUTTON DIGITAL PUSHBUTTON WITH LED (DEFAULT = OFF) PUSH BOTH BUTTONS 7

8 Typical Operating Circuits (continued) R R, C SETS PULSE WIDTH C DIGITAL PUSHBUTTON WITH LED (DEFAULT = ON) PUSHBUTTON ONE-SHOT A B 4-POSITION PUSHBUTTON SELECTOR SWITCH LED STATE A B STATE STATE 1 STATE 2 STATE 3 8

9 PROCESS: BiCMOS Chip Information Package Information For the latest package outline information, go to PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 6 Thin SOT23 Z 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. Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.