YB1682
2A 380KHz 20V PWM Buck DC/DC Converter
Function Block
Figure 3: Function Block
Functional Description
VIN
This is the positive input supply for the IC
switching regulator. A suitable input bypass
capacitor must be present at this pin to
minimize voltage transients and to supply
the switching currents needed by the
regulator.
Gnd
Circuit ground.
SW
Internal switch. The voltage at this pin
switches between (V
IN
– V
GS
) and
approximately – 0.5V, with a duty cycle of
approximately V
OUT
/ V
IN
. To minimize
coupling to sensitive circuitry, the PC board
copper area connected to this pin should
be kept a minimum.
YB1682 Rev.1.0
FB
Senses the regulated output voltage to
complete the feedback loop.
EN
Allows the switching regulator circuit to be
shutdown using logic level signals thus
dropping the total input supply current to
approximately 30µA.
Pulling this pin below a threshold voltage of
approximately 0.7V turns the regulator
down, and pulling this pin above 1.3V (up to
a maximum of 12V) shuts the regulator on.
For automatic star up condition, can be
implemented by the addition of a resistive
voltage divider from V
IN
to GND.
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