ZXCT1008FTA View Datasheet(PDF) - Diodes Incorporated.

Part Name

Description

Manufacturer

ZXCT1008FTA

INCREASED AMBIENT TEMPERATURE HIGH-SIDE CURRENT MONITOR

Diodes Incorporated. 

ZXCT1008

Application Information (Continued)

ZXCT1008 Application with High Transients

Where RLOAD represents any load including DC motors, a charging

battery or further circuitry that requires monitoring, RSENSE can be

selected on specific requirements of accuracy, size and power

rating.

An additional resistor, RLIM can be added in series with ROUT (as

below), to limit the current from IOUT. Any circuit connected to VOUT

will be protected from input voltage transients. This can be of

particular use in automotive applications where load dump and other

common transients need to be considered. The Zener Z1 provides

additional protection for local dump, reverse battery and high

voltage transient incidents.

Assuming the worst case condition of VOUT = 0V; providing a low

impedance to a transient, the minimum value of RLIM is given by:

RLIM(min) = (VPK – VMAX)/IPK

where

VPK = Peak transient voltage to be withstood

VMAX = Maximum working voltage = 20V

IPK = Peak output current = 40mA

The maximum value of RLIM is set by VIN(MIN), VOUT(MAX) and the

dropout voltage (see transfer characteristic on page 3) of the

ZXCT1008:

PCB Trace Shunt Resistor for Low Cost Solution

The figure below shows output characteristics of the device when

using a PCB resistive trace for a low cost solution in replacement

for a conventional shunt resistor. The graph shows the linear rise in

voltage across the resistor due to the PTC of the material and

demonstrates how this rise in resistance value over temperature

compensates for the NTC of the device.

The figure opposite shows a PCB layout suggestion. The resistor

section is 25mm x 0.25mm giving approximately 150mΩ using 1oz

copper. The data for the normalized graph was obtained using a 1A

load current and a 100Ω output resistor. An electronic version of the

PCB layout is available through Diodes applications group.

Figure 2. ZXCT1008 with Additional Current Limiting Resistor RLIM

and Zener Z1

I ( A )=

Where

( I ( I )-( D +

( A)

( A )))

VIN(MIN) = Minimum Supply Operating Voltage

VDP = Dropout Voltage

VOUT(MAX) = Maximum Operating Output Voltage

Layout shows area of shunt resistor compared to SOT23

package. Not actual size.

ZXCT1008

Document number: DS33440 Rev.8 - 2

5 of 8

www.diodes.com

December 2017

© Diodes Incorporated

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