ADM6315

Rev. E | Page 7 of 12

THEORY OF OPERATION

MANUAL RESET INPUT

INTERFACING TO OUTPUT OF OTHER DEVICES

The ADM6315 also provides an additional input, MR. This

input can be used either as a means for the system operator to

reset the system manually via a switch or for a digital circuit to

reset the system.

The ADM6315 series is designed to integrate with as many devices

as possible. One feature of the ADM6315 is the RESET open-

drain output, which can sink current from sources with a

suitable for use in more diverse applications.

MR

The

input (typically) ignores negative-going pulses that are

faster than 100 ns, and it is guaranteed to accept any negative-

going input pulse of a duration greater than or equal to 1 μs. If

BENEFITS OF A VERY ACCURATE RESET THRESHOLD

Because the ADM6315 series can operate effectively even when

there are large degradations of the supply voltages (due to an

accurate internal voltage reference circuit), the possibility of a

malfunction during a power failure is greatly reduced.

MR is connected to long cables or is used in a noisy environment,

placing a 1 μF decoupling capacitor between the MR input and

ground further improves the glitch immunity of the ADM6315.

RESET

RESET ACTIVE TIMEOUT

RESET

VOL

DELAY

DETAILED DESCRIPTION

TRANSIENT IMMUNITY

The ADM6315 is designed to protect the integrity of a system’s

operation by ensuring the proper operation of the system

during power-up, power-down, and brownout conditions.

As well as being an accurate reset circuit, the ADM6315 has

good immunity from negative-going transients (see Figure 7).

Because of this characteristic, the ADM6315 is suitable for use

in noisy environments.

RESET

When the ADM6315 is powered up, the

output of the

ADM6315 remains low for a period typically equal to the RESET

active timeout period. This feature allows adequate time for the

system to power up correctly and for the power supply to

stabilize before any devices are brought out of reset and allowed

to begin executing instructions. Initializing a system in this way

provides a more reliable startup for microprocessor systems.

RESET

1 mV/μs), the ADM6315 produces a reset in 35 μs typical.

Producing a reset this fast means that the entire system can be

reset together before any part of the system’s voltage falls below

its recommended operating voltage. This system reset can avoid

dangerous and/or erroneous operation of a microprocessor-

based system.

Figure 7 shows the

comparator overdrive (the maximum

magnitude of negative-going pulses with respect to the typical

reset threshold) vs. the pulse duration without a reset.