ADM6710

Preliminary Technical Data

Rev. PrB | Page 6 of 8

THEORY OF OPERATION

The ADM6710 is a compact, low power supervisory circuit

capable of monitoring up to four voltages in multivoltage

applications. If a monitored power supply voltage falls below the

minimum voltage threshold, a single active low output asserts,

triggering a system reset.

The ADM6710 includes several voltage threshold options for

monitoring 5.0 V, 3.3 V, 3.0 V, 2.5 V and 1.8 V supplies. It also

provides up to three adjustable thresholds for monitoring

voltages down to 0.62 V. See the Ordering Guide section for a

list and description of all options available.

The ADM6710 includes precision comparators, an accurate

band gap reference, and a series of internally-trimmed resistor

divider networks to set the factory-fixed reset threshold

options. The resistor networks scale the specified INx reset

voltages to match the internal band gap reference/comparator

voltage.

Adjustable threshold options bypass the internal resistor

networks and connect directly to one of the comparator inputs.

External resistor divider networks must be used to scale

voltages down for monitoring at the adjustable inputs. The

ADM6710Q provides a separate unmonitored power supply

The internal comparators each typically have a hysteresis of

0.3% with respect to its reset threshold. This built-in hysteresis

improves the device’s immunity to ambient noise without

noticeably reducing the threshold accuracy. The ADM6710 is

unaffected by short input transients.

MONITORED

SUPPLIES

MICROPROCESSOR

ADM6710

GND

RESET

Figure 3. Typical Applications Circuit

INPUT CONFIGURATION

The ADM6710 provides numerous monitor choices with

adjustable reset thresholds. Typically, the threshold voltage at

each adjustable INx input is 0.62 V. To monitor a voltage greater

than 0.62 V, connect a resistor divider network to the circuit as

depicted in Figure 4, where

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+

=

2

2

1

62

.

0

R

R

R

V

V

INTH

R1

R2

Figure 4. Setting the Adjustable Monitor

The ADM6710Q contains an internal voltage clamp at each of

the adjustable voltage inputs. Input voltages greater than 1.5 V

induce a higher input current.

resistant to short power supply glitches. To increase noise

immunity in noisy applications, place a 0.1 μF capacitor

Do not allow unused monitor inputs to float or to be grounded.

Connect these inputs to a supply voltage greater than their

specified threshold voltages. In the case of unused INx

adjustable inputs, limit the bias current by connecting a 1 MΩ

the ADM6710Q).

RESET OUTPUT CONFIGURATION

The ADM6710 has a reset timeout period of 200 ms (typical).

The output is open drain with a weak internal pull-up to the

In many applications that interface with other logic devices,

there is no requirement for an external pull-up resistor. An

external pull-up resistor to any voltage, ranging from 0 V to

5.5 V, can overdrive the internal pull-up when interfacing to

different logic supply voltages (see Figure 5). Reverse current

the internal circuitry.

ADM6710

RESET

RESET

5V

100kΩ

Figure 5. Interface with a Different Logic Supply Voltage

is a monitored voltage. If a supply voltage drops below its

associated threshold, the reset output asserts low and remains