APW7057KC-TRG データシートの表示（PDF） - Anpec Electronics
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APW7057KC-TRG Datasheet PDF : 15 Pages
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APW7057
Electrical Characteristics (Cont.)
Unless otherwise specified, these specifications apply over V =5V, V =12V and T = 0~70 oC. Typical values are
CC
BOOT
A
at T =25oC.
A
Symbol
Parameter
Test Conditions
APW7057
Unit
Min. Typ. Max.
SOFT-START AND SHUTDOWN
TSS
Soft-Start Interval
-
2
-
mS
Shutdown Threshold
VOCSET Falling
-
1.25
-
V
OCSET Shutdown Hysteresis
-
20
-
mV
Function Pin Description
BOOT (Pin 1)
OCSET (Pin 7)
This pin provides the supply voltage to the high side
MOSFET driver. A voltage no greater than 13V can be con-
nected to this pin as a supply to the driver. For driving
logic level N-channel MOSEFT, a bootstrap circuit can be
use to create a suitable driver’s supply.
UGATE (Pin 2)
This pin provides gate drive for the high-side MOSFET.
GND (Pin 3)
Signal and power ground for the IC. All voltage levels are
measured with respect to this pin. Tie this pin to the ground
plane through the lowest impedance connection available.
LGATE (Pin 4)
This pin provides the gate drive signal for the low side
MOSFET.
VCC (Pin 5)
This is the main bias supply for the controller and its low
side MOSFET driver. Must be closely decoupled to GND
(Pin 3). DO NOT apply a voltage greater than 5.5V to this
pin.
FB (Pin 6)
This pin is the inverting input of the error amplifier and it
receives the feedback voltage from an external resistive
divider across the output (V ). The output voltage is de-
OUT
termined by:
VOUT
=
0.8V(1+
ROUT
RGND
)
where ROUT is the resistor connected between VOUT
and FB while RGND is the resistor connected from FB to
GND.
This pin serves two functions: as a shutdown control and
for setting the over current limit threshold. Pulling this pin
below 1.25V shuts the controller down, forcing the UGATE
and LGATE signals to be at 0V. A soft-start cycle will be
initiated upon the release of this pin.
A resistor (Rocset) connected between this pin and the drain
of the high side MOSFET will determine the over current
limit. An internally generated 40µA current source will flow
through this resistor, creating a voltage drop. This volt-
age will be compared with the voltage across the high
side MOSFET. The threshold of the over current limit is
therefore given by:
IOI = 40uA x ROCSET
RDS(ON)
An over current condition will cycle the soft-start function.
After three consecutive cycles and if the fault condition
persists, the controller will be shut down. To restart the
controller, either recycle the VCC supply or momentarily
pull the OSCSET pin below 1.25V.
PHASE (Pin 8)
This pin is connected to the source of the high-side
MOSFET and is used to monitor the voltage drop across
the high-side MOSFET for over-current protection.
Copyright © ANPEC Electronics Corp.
4
Rev. A.5 - Jun., 2008
www.anpec.com.tw
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