ZXCT1032 Datasheet, PDF (1/10 Pages) Zetex Semiconductors – High-side inrush controller and electronic fuse

ZXCT1032
High-side inrush controller and electronic fuse
Description
The ZXCT1032 is a high-side current monitor
that drives a PMOS or PNP transistor to
provide in-rush current limit and over-current
protection. The ZXCT1032 includes a high
accuracy high-side current monitor, a start-up
timer and a re-try inhibit timer.
The ZXCT1032 takes the voltage developed
across a current shunt resistor and compares
this with an externally set trip point. It works
in three modes:
• Linear soft-start
• Over-current detector
• Over-current disconnect/fuse
Linear soft-start
Upon power up the ZXCT1032 enters a linear
soft-start mode. During which the output
current ramps up from zero to a maximum
user defined trip point. The trip point is set by
the voltage on I_SET pin and R_SENSE.
The ramp rate is determined by capacitor C_T.
The soft start ensures that capacitive loads are
smoothly charged without causing excessive
power supply startup transients.
Over-current detectior
When external capacitor CT has charged up
above the V_ISET the ZXCT1032 switches from its
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
• Accurate high-side current sensing
• User defined and dynamically adjustable
trip current
• Load switch control
• Fault flag logic output
• User defined ramp and inhibit timers
• SO8 package
• Temperature range -40 to 85°C
While in this mode the internal current monitor
continually checks the output current and
compares it to the trip-current level determined
by V_ISET.
Over-current disconnect/fuse
If the trip current limit is exceeded at any time the
ZXCT1032 enters its Over-current disconnect
mode. The drive pin is driven high, turning the
pass MOSFET off; the flag output goes low
indicating a fault.
The drive and flag outputs are latched in these
states for a period determined by C_T, V_ISET and the
internally set discharge current (3µA typical). After
C_T has discharged to 80mV the ZXCT1032 will
restart into its linear soft-start mode.
The C_T charge and discharge times have been
ratioed to so that the power dissipation in the
pass MOSFET should allow indefinite operation
in the event of a continuous load failure.
Pin 3 description:
Determines the load current trip level or
constant current level. ISET can be left open
circuit (internal 2.1V reference) or driven via a
DC voltage or µC PWM output. Its source
impedance is 50k⍀.
Applications
• Electronic fuse
• Short circuit protected supply feed
• Hot swap
• Power over twisted pair
Ordering information
Order code
Pack
ZXCT1032N8TA SO8
Part mark
1032
Reel size
7”
Tape width
12mm
Quantity per reel
500
Issue 4 - June 2007
1
© Zetex Semiconductors plc 2007
www.zetex.com