ZXCT1032N8TA

ZXCT1032 High-side inrush controller and electronic fuse Description The ZXCT1032 is a high-side current monitor While in this mode the internal current monitor that drives a PMOS or PNP transistor to continually checks the output current and provide in-rush current limit and over-current compares it to the trip-current level determined protection. The ZXCT1032 includes a high by V . ISET accuracy high-side current monitor, a start-up Over-current disconnect/fuse timer and a re-try inhibit timer. If the trip current limit is exceeded at any time the The ZXCT1032 takes the voltage developed ZXCT1032 enters its Over-current disconnect across a current shunt resistor and compares mode. The drive pin is driven high, turning the this with an externally set trip point. It works pass MOSFET off the flag output goes low in three modes: indicating a fault. Linear soft-start The drive and flag outputs are latched in these Over-current detector states for a period determined by C , V and the T ISET Over-current disconnect/fuse internally set discharge current (3A typical). After C has discharged to 80mV the ZXCT1032 will Linear soft-start T restart into its linear soft-start mode. Upon power up the ZXCT1032 enters a linear soft-start mode. During which the output The C charge and discharge times have been T current ramps up from zero to a maximum ratioed to so that the power dissipation in the user defined trip point. The trip point is set by pass MOSFET should allow indefinite operation the voltage on I pin and R . SET SENSE in the event of a continuous load failure. The ramp rate is determined by capacitor C . T Pin 3 description: The soft start ensures that capacitive loads are Determines the load current trip level or smoothly charged without causing excessive constant current level. ISET can be left open power supply startup transients. circuit (internal 2.1V reference) or driven via a Over-current detectior DC voltage or C PWM output. Its source When external capacitor CT has charged up impedance is 50k . above the V the ZXCT1032 switches from its ISET soft-start mode to its over-current detection mode. During this mode the external MOSFET will be fully enhanced reducing the its voltage drop and power dissipation. Features Applications Accurate high-side current sensing Electronic fuse User defined and dynamically adjustable Short circuit protected supply feed trip current Hot swap Load switch control Power over twisted pair Fault flag logic output User defined ramp and inhibit timers SO8 package Temperature range -40 to 85C Ordering information Order code Pack Part mark Reel size Tape width Quantity per reel ZXCT1032N8TA SO8 1032 7 12mm 500 Issue 4 - June 2007 1 www.zetex.com Zetex Semiconductors plc 2007ZXCT1032 Typical application circuit Pinout connections SO8 V IN 1 8 GND- IN+ R SENSE 2 7 6 C N/C 8 T IN+ IN- 3 6 ISET IN- 5 Drive ZXCT 4 5 Flag Drive ISET 1032 Load 3 Top view GND Flag C T 1 2 4 C T C GND Pin description Pin Name Description 1 GND Ground reference for I and Flag pins. Most negative terminal of the SET device. No other pin should go below this voltage. 2C An external capacitor is connected to this pin and is used to determine T the period for constant-current mode and the timeout before restarting. To reduce excessive heating during the soft start mode capacitors less than 220nF are reocmmended. 3 ISET Determines the load current trip level or constant current level. This can be driven via a DC voltage or via a C PWM output. V = (V -150mV)/10 SENSE ISET An input <100mV will disable the high-side switch (i.e. set I = 0) OUT If left open-circuit, an accurate internal DC reference of 2.1V and source impedance of 50k is used to set the voltage on this pin. (External drivers must take this reference into account.) 4 Flag This is an active low open collector output that goes low whenever the current limit set by the choice of R and I is reached or in the SENSE SET event of a shorted load. 5 Drive This is the output drive pin to the external high side referred switch on the ZXCT1032, capable of driving PMOS and PNP transistors. 6 IN- The load referred input to the current monitor control loop. 7 N/C Not connected 8 IN+ Acts as both the supply pin to the ZXCT1032 and the supply referred sense input to the current monitor control loop. Issue 4 - June 2007 2 www.zetex.com Zetex Semiconductors plc 2007