MAX16054AZT+T Datasheet MAX16054AZT+T | P4-P6

Detailed Description

Theory of Operation

The MAX16054 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 OUT to go high and OUT to

go low. The output state remains latched after the

switch is released/opened. Closing the switch again

causes OUT to go low and OUT 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 low-

to-high until the input is stable for at least 50ms (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 flip-

flop), the XNOR gate issues a counter reset. When the

switch input state is stable for the full qualification peri-

od, 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 clos-

ing switch debounce operation.

A rising pulse at CLEAR resets the T flip-flop and pulls

OUT low and OUT high.

MAX16054

On/Off Controller with Debounce and

±15kV ESD Protection

4 _______________________________________________________________________________________

Functional Diagram

XNOR

UNDERVOLTAGE

LOCKOUT

CLR

COUNTER

CLR

OSC

OUT

CLEAR

ESD

PROTECTION

MAX16054

Undervoltage Lockout

The undervoltage-lockout circuitry ensures that the out-

puts are at the correct state on power-up. While V

less than the 2.1V (typ) undervoltage threshold and

greater than 1.0V, OUT remains low and transitions at

IN are ignored.

Robust Switch Input

The switch input (IN) 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 61000-4-2 Air-Gap

Discharge test and ±8kV per the IEC 61000-4-2 Contact-

Discharge test.

Since there is a 63kΩ (typ) pullup resistor connected to

IN, driving the input to -25V draws approximately 0.5mA

from the V

supply. Driving the input to +25V causes

approximately 0.32mA of current to flow back into the

supply. If the total system V

supply current is

less than the current flowing back into the V

supply,

rises above normal levels. In some low-current sys-

tems, a zener diode on V

may be required.

±15kV ESD Protection

ESD-protection structures are incorporated on all pins

to protect against electrostatic discharges encountered

during handling and assembly. The MAX16054 has

extra protection against static electricity to protect

against ESD of ±15kV at the switch input without dam-

age. The ESD structures withstand high ESD in all

states: normal operation, shutdown, and powered

down. A design advantage of the MAX16054 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 61000-4-2.

3) ±15kV using the IEC 61000-4-2 Air-Gap method.

MAX16054

On/Off Controller with Debounce and

±15kV ESD Protection

_______________________________________________________________________________________ 5

UVLO

OUTPUT OF D

FLIP-FLOP

(INVERTED

IN AFTER

DEBOUNCE)

OUT

CLEAR

Figure 1. MAX16054 Timing Diagram

MAX16054

Human Body Model

Figure 2a shows the Human Body Model, and Figure

2b shows the current waveform it generates when dis-

charged 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.

IEC 61000-4-2

The IEC 61000-4-2 standard covers ESD testing and

performance of finished equipment; it does not specifi-

cally refer to integrated circuits. The MAX16054 helps in

the design of equipment that meets IEC 61000-4-2, with-

out the need for additional ESD-protection components.

The major difference between tests done using the

Human Body Model and IEC 61000-4-2 is higher peak

current in IEC 61000-4-2, because series resistance is

lower in the IEC 61000-4-2 model. Hence, the ESD with-

stand voltage measured to IEC 61000-4-2 is generally

lower than that measured using the Human Body Model.

Figure 3a shows the IEC 61000-4-2 model, and Figure

3b shows the current waveform for the IEC 61000-4-2

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 resis-

tance. Its objective is to emulate the stress caused by

contact that occurs with handling and assembly during

manufacturing.

On/Off Controller with Debounce and

±15kV ESD Protection

6 _______________________________________________________________________________________

CHARGE-CURRENT

LIMIT RESISTOR

DISCHARGE

RESISTANCE

STORAGE

CAPACITOR

100pF

1MΩ

1500Ω

HIGH-

VOLTAGE

SOURCE

DEVICE

UNDER

TEST

Figure 2a. Human Body ESD Test Model

CHARGE-CURRENT

LIMIT RESISTOR

DISCHARGE

RESISTANCE

STORAGE

CAPACITOR

150pF

50MΩ to 100MΩ

330Ω

HIGH-

VOLTAGE

SOURCE

DEVICE

UNDER

TEST

Figure 2b. Human Body Current Waveform

100%

90%

36.8%

TIME

CURRENT WAVEFORM

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

10%

AMPERES

Figure 3a. IEC 61000-4-2 ESD Test Model

= 0.7ns TO 1ns

30ns

60ns

100%

90%

10%

PEAK

Figure 3b. IEC 61000-4-2 ESD Generator Current Waveform

P1-P3 P4-P6 P7-P9

MAX16054AZT+T

Mfr. #:

Buy MAX16054AZT+T

Manufacturer:

Maxim Integrated

Description:

Supervisory Circuits w/Debounce

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New from this manufacturer.

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MAX16054AZT+T