ZIOL2201 datasheet(53/92 Pages) RENESAS

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ZIOL2xxx Datasheet

April 26, 2016

3.5.

The Power Fail Detector

3.5.1.

Overview

The Power-Fail detector function is split into two tasks. The first task is the “Line-Fault” (LF) detection which shall

recognize a situation in which the ZIOL2xxx is not powered regularly. This situation can happen if for instance the

wiring between device and host port is not performed in the right way (interchanged wires, broken wires).

The second task is the “Under-Voltage” (UV) detector which monitors the supply voltage at the VDD pin of the

ZIOL2xxx. The purpose of this detector is ensure a proper working of the HV drivers COM and AUX which is not

guaranteed if the supply voltage at VDD drops below the allowed minimum value.

Figure 3.20 illustrated the working principle of both the LF and the UV detector in combination with the further

processing to the detected events (LINE_FAULT and UNDER_VOLTAGE). Based on the IC configuration

(LF_ENABLE, UV_ENABLE flags) each event (or both events) may activate the lock for both channels exactly for

the period the respective event is present. The new status register [26] allows diagnosing what event is present or

was present in the past.

Figure 3.20 PFD Working Principle

VDD

VSS

Standard

Cable

L+

L-

PFD

(previously M_EN

)

Status

reg[18]

Bit7

LF_ENABLE

Config.reg[9][6]

COM/AUX OFF

(tristate)

Same reaction as

caused by OVT

Window

comparator

Vupper_bound

Vlower_bound

ZIOL2401B

49.9k

(1%)

210k

(1%)

Vsense

comparator

Vref

LOCK_PF

Status

reg[26]

Bit0

Bit1

UNDER_VOLTAGE

LINE_FAULT

Analog circuitry

Digital circuitry

UV_ENABLE

Config.reg[9][5]

Clear by

Read (r/rst)

Anti-

Bouncing

Filter

Anti-

Bouncing

Filter

AND

3.5.2.

Line-Fault Detector

The Line-Fault (LF) detection feature assumes the utilization of both channels in device mode. In the case one

channel is used only, the number of detectable failures be reduced accordingly. For more information about

detectable failures, please refer to the Appendix C.

The optional (configurable) detection of the situation of an abnormal power supply of the IC will be achieved by a

ratiometric working voltage sensor. As sensor input works the PFD pin (formerly M_EN) in combination with two

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