Datasheet ZXCT1009 (Diodes) - 4

ZXCT1009 HIGH-SIDE CURRENT MONITOR Typical Characteristics (cont.) Power Dissipation Application Information
The maximum allowable power dissipation of the device for The following text describes how to scale a load current normal operation (PMAX), is a function of the package junction to to an output voltage. ambient thermal resistance (θJA), maximum junction temperature (T V JMAX), and ambient temperature (TAMB), according to the SENSE = VIN - VLOAD 1 expression: VOUT = 0.01 x VSENSE x ROUT PMAX = (TJMAX – TAMB) / θJA E.g. The device power dissipation, P A 1A current is to be represented by a 100mV output D is given by the expression: voltage: PD = IOUT(VIN -VOUT) W 1) Choose the value of RSENSE to give 50mV > VSENSE > 500mV at full load. For example VSENSE = 100mV at 1.0A. RSENSE = 0.1/1.0 => 0.1Ω. 2) Choose ROUT to give VOUT = 100mV, when VSENSE = 100mV. Rearranging
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for Rout gives: ROUT = VOUT /(VSENSE x 0.01) ROUT = 0.1 / (0.1 x 0.01) = 100Ω ZXCT1009 4 of 8 April 2011 Document number: DS33441 Rev. 12 - 2
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