AMC3202DMF
APPLICATION SUMMARY
The AMC3202 incorporates a current mode control scheme, in which the duty cycle of the
switch is directly controlled by switch current rather than by output voltage. The output of
the oscillator turns on the power switch at a frequency of 280kHz as shown in the block
diagram. The power switch is turned off by the output of the PWM comparator.
A TTL low voltage will shut down the chip and high voltage enable the chip through
EN pin. This pin may also be used to synchronize the part to nearly twice the base
oscillator frequency. In order to synchronize to a higher frequency, a positive transition
turns on the power switch before the output of the oscillator goes high, thereby resetting
the oscillator. The synchronization operation allows multiple power supplies to operate at
the same frequency. If synchronization is not used,this pin should be either tied high or
left floating for normal operation.
Component Selection:
A M C 3202D M F
The AMC3202 develops a 1.276V reference from the FB pin to ground. Output voltage is
set by connecting the FB pin to an output resistor divider and the maximum output voltage
is determined by the VSW pin maximum voltage minus the output diode forward voltage.
Referring to typical application circuit, the output voltage is set by the below formula(1):
where, VF is the output diode DF forward voltage.
When choosing the inductor, one must consider factors such as peak current, core and
ferrite material, output voltage ripple, EMI, temperature range, physical size, and cost.
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TGS [ Tiger Electronic Co.,Ltd ]
