ZXCT1020E5TA

ZXCT1020 ZXCT1020 Low offset current output current monitor Description The ZXCT1020 is a precision high-side current Current output enables the user to set the gain sense monitor. Using this type of device via these external resistors. Using two external eliminates the need to disrupt the ground resistors to set the gain ensures optimal plane when sensing a load current. versatility as the transconductance can be varied to meet the output impedance requirements of The ZXCT1020 uses two external resistors to the load that the ZXCT1020 has to drive. set the overall voltage gain for applications where improved accuracy at small sense The very low offset voltage enables a typical voltages is required. For fixed gain variants accuracy of 3% for sense voltages of only 10mV, Zetex offers the ZXCT1021 (G=10) and giving better tolerances for small sense ZXCT1022 (G=100). resistors necessary at higher currents. The ZXCT1020 footprint follows that of the The wide input voltage range of 20V down to as ZXCT1021/2 with only 2 additional resistors low as 2.5V make it suitable for a range of required: applications. With a minimum operating current of just 25A, combined with its SOT23-5 One resistor between pins 1 and 4 for setting package make it suitable for portable battery transconductance, and the other between equipment too. pins 3 and 2 for setting overall gain. Features Applications Accurate high-side current sensing Battery chargers Versatile current output scaling Over-current monitor 2.5V - 20V operating range Motherboard power supply current measurement 25A quiescent current Level translating 1% typical accuracy Programmable current source SOT23-5 package Pinout information Typical application circuit I S+ 1 5 S- L R S R SH S- V B (LOAD) GND 2 5 4 S+ 1 - OUT 3 4 V B + Top view V OUT 3 2 ZXCT1020 R G GND Ordering information Order reference Package Device Status Reel size Quantity Tape width marking (inches) per reel (mm) ZXCT1020E5TA SOT23-5 1020 Preview 7 3000 8 Issue 1 - August 2007 1 www.zetex.com Zetex Semiconductors plc 2007ZXCT1020 Absolute maximum ratings Voltage on V with respect to GND pin -0.5V to 20V B (a) (b) -0.5V to V +0.5V Voltage on S+ , S- , OUT with respect to GND pin B (c) (d) V -0.5V to +2.5V SENSE Junction temperature -40C to125C Storage temperature -55C to 150C Package power dissipation (T = 25C) SOT23-5 300mW amb NOTES: (a) Subject to V + never going 6V below V . SENSE B (b) Subject to absolute maximum V not being exceeded. SENSE (c) V is defined as the voltage difference across the sense resistor. and is the voltage across resistor R plus the SENSE SH voltage between S+ and S-. (d) V might need to be reduced when used with smaller values of R and at larger rails due to increased power dissipation. SENSE SH Pin out information Pin Name Pin function 1 S+ Positive sense input. Should be tied to positive side of sense resistor via resistance (R ) of the order of 150 to 1.5k . SH 2 GND Ground and substrate connection of device. 3 OUT Current output. A gain setting resistor (R ) referenced to GND should be G connected to this pin to set overall voltage gain of: Gain = R /R G SH The resistance, R , placed on out will set the ZXCT1020 output impedance equal G to R . When driving low impedance loads both R and R should be reduced. G G SH 4V Input voltage pin. Provides bias to current monitor and should be tied to the B rail whose current is being monitored. 5 S- High impedance negative sense voltage input Recommended operating conditions Parameter Min. Max. Units V Common-mode sense input range 2.5 20 V SENSE+ (*) V 2.5 20 V Bias pin input voltage range B V Differential sense Input voltage range 0 1.5 V SENSE V Output voltage range 0 V - 1 V OUT SENSE- R Shunt resistor value 120 2000 SH T Ambient temperature range -40 85 C A NOTES: (*) For best performance V and V should be referred to the rail whose current is being measured. B SENSE+ Recommended resistor gain setting combinations Gain R R SHUNT GAIN 10 1.5k 15k 20 750 15k 50 300 15k 100 150 15k Issue 1 - August 2007 2 www.zetex.com Zetex Semiconductors plc 2007