PT7M6709 Datasheet, PDF(7/12 Page) Pericom Semiconductor Corporation

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PT7M6709/6714

Multi-voltage Supervisor

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Fig.3 PFO Pull-up and Pull-down Response of PT7M6714, CPFO = 47pF

Function Description

The PT7M6709/PT7M6714 have an internally trimmed threshold that minimizes or eliminates the need for external

components. The four open-drain outputs have weak (10Î¼A) internal pull-ups to Vcc, allowing them to interface easily with other

logic devices. The weak internal pull-ups can be overdriven by external pull-ups to any voltage from 0V to 5.5V. Internal circuitry

prevents current flow from the external pull-up voltage to Vcc. The outputs can be wire-ORed for a single power-good signal.

The PT7M6709 quad voltage monitor includes an accurate reference, four precision comparators, and a series of internally

trimmed resistor-divider networks to set the factory-fixed threshold options. The resistor networks scale the specified IN_reset

voltages to match the internal reference/comparator voltage. Adjustable threshold options bypass the internal resistor networks and

connect directly to one of the comparator inputs (an external resistor-divider network is required for threshold matching). The

PT7M6709 monitors power supplies with either 5% or 10% tolerance specifications, depending on the selected version. Additional

high-input-impedance comparator options can be used as an adjustable voltage monitor, general-purpose comparator, or digital-

level transiator.

The PT7M6714 quad voltage monitor/reset offers one fixed input with internal timing for ïP reset, three power-fail

comparators, and a manual reset input( MR ). RESET asserts low when Vcc drops below its threshold or MR is driven low. Each

of the three power-fail inputs connects directly to one of the comparator inputs.

When any input is higher than the threshold level, the output is high. The output goes low as the input drops below the

threshold voltage. The undervoltage lockout circuitry remains active and all outputs remain low with Vcc down to 1V(Fig.4 and

Fig.5).

Application Information

Hysteresis

The PT7M6709/PT7M6714 has built-in hysteresis which is typically 0.3% of the threshold voltage, so external resistive network

used for causing hysteresis is not required.

Under-voltage Detection Circuit

The open-drain outputs of PT7M6709/PT7M6714 can be configured to detect an under-voltage condition.

The PT7M6709/PT7M6714 can also be used in applications such as system supervisory monitoring, multi-voltage level detection,

and Vcc bar graph monitoring.

12-07-0002

PT0235-2

07/05/12

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