EA4533BYH Datasheet, PDF (6/17 Pages) Active-Semi, Inc – Wide-Input Sensorless CC/CV Step-Down DC/DC Converter

FUNCTIONAL DESCRIPTION
driven by logic using HSB as the positive rail. This
pin is charged to V_SW + 5V when the Low-Side
Power Switch turns on. The COMP voltage is the
integration of the error between FB input and the
internal 0.808V reference. If FB is lower than the
reference voltage, COMP tends to go higher to
increase current to the output. Output current will
increase until it reaches the CC limit set by the ISET
resistor. At this point, the device will transition from
regulating output voltage to regulating output
current, and the output voltage will drop with
increasing load.
The Oscillator normally switches at 125kHz.
However, if FB voltage is less than 0.6V, then the
switching frequency decreases until it reaches a
typical value of 18kHz at V_FB = 0.15V.
Over Voltage Protection (ACT4533A)
The ACT4533A has an OVP pin. If the voltage at
this pin exceeds 0.8V, the IC shuts down high-side
switch. There is a 4µA pull-up current at this pin.
EN/OVP Pin (ACT4533B)
The ACT4533B has an enable input and OVP input
for turning the IC on and off.
If the voltage at this pin rises above 0.65V, the IC is
enabled. The EN contains a 60mV hysteresis and
4µA pull-up current source.
If the voltage at this pin is between 0.65V and
2.26V, the IC operates normally; if the voltage at
this pin exceeds 2.26V, the IC shuts down high-side
switch. The OVP contains a 500mV hysteresis and
4µA pull-up current source.
Thermal Shutdown
The ACT4533A/B disables switching when its
junction temperature exceeds 155°C and resumes
when the temperature has dropped by 25°C.
ACT4533A/B
Rev 0, 14-Aug-13
Innovative Power^TM
-6-
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