FAN1577A Datasheet, PDF (3/15 Pages) Fairchild Semiconductor – Dual Synchronous DC/DC Controller

Pin Configuration & Marking Information
20
TAHAA
FAN1577AM
1
F: Fairchild Logo
T: Assembly Plant Code
A: Year Code
H: Week Code
AA: Die Run Code
Figure 3. Marking Diagram
Figure 4. Marking Legend
Figure 5. Pin Assignments
(Top View)
Pin Definitions
Name Pin #
Type
Description
RT
1
Frequency
Select
An external resistor connecting this pin to GND can program the switching
frequency. The switching frequency is 61kHz when RT is open and becomes
340kHz when RT is shorted to ground.
IN1
2
Feedback
Inverting input of the error amplifier normally connected to the switching power
supply output through a resistor divider.
COMP1
3
Compensation
Output of the error amplifier and input to the PWM comparator. It is used for
feedback-loop compensation.
SS1/ENB 4
Soft-Start / A 35/15µA internal current source charging an external capacitor for soft-start.
Enable
Pull down this pin and pin 17 to disable the chip.
CLP1
5
Over-Current Over-current protection for high-side MOSFET. Connect a resistor from this pin
Protection to the high-side supply voltage to program the OCP level.
BST1
6 Boost Supply Supply for high-side driver. Connect to the internal bootstrap circuit.
DH1
7 High-Side Drive Channel 1, high-side MOSFET gate driver pin.
CLN1
8
Switch Node
Switch-node connection to the inductor. For channel 1, high-side driver’s
reference ground.
DL1
9 Low-Side Drive Low-side MOSFET gate driver pin.
PGND 10 Driver Ground Driver circuit reference. Connect to low-side MOSFET GND.
VCC 11 Power Supply Supply voltage input.
DL2
12 Low-Side Drive Low-side MOSFET gate driver pin.
CLN2
13
Switch Node
Switch-node connection to the inductor. For channel 2, high-side driver’s
reference ground.
DH2
14 High-Side Drive Channel 2 high-side MOSFET gate driver pin.
BST2 15 Boost Supply Supply for high-side driver. Connect to the internal bootstrap circuit.
CLP2
16
Over-Current Over-current protection for the high-side MOSFET. Connect a resistor from this
Protection pin to the high-side supply voltage to program the OCP level.
SS2/ENB 17
Soft-Start / A 35/15µA internal current source charging an external capacitor for soft-start.
Enable
Pull down this pin and pin 4 to disable the chip.
COMP2
18
Compensation
Output of the error amplifier and input to the PWM comparator. It is used for
feedback-loop compensation.
IN2
19
Feedback
Inverting input of the error amplifier. It is normally connected to the switching
power supply output through a resistor divider.
GND 20 Analog Ground The reference of internal control circuits.
© 2010 Fairchild Semiconductor Corporation
FAN1577A • Rev. 1.0.0
3
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