sc2677 Semtech Corporation, sc2677 Datasheet - Page 4

• Manufacturer Part Number: sc2677
• Description: Sc2677 Dual Synchronous Voltage-mode Controller With Current-sharing Circuitry
• Manufacturer: Semtech Corporation

EXPANDED PIN DESCRIPTION
Pin 1: (VREF)
Internal 0.5V reference. Connected to the + input of
the master channel error amplifier.
Pin 2: (FREQ)
External frequency adjustment. Connect a resistor to
AGND to set the switching frequency. Please see
more information in Application section.
Pin 3: (VCC)
Bias pin for the controller. Connect a ceramic
decoupling capacitor from this pin to AGND with
minimum trace length.
Pin 4: (+IN2)
Pin 5, 16: (-IN2, -IN1)
Pin 6, 15: (COMP2, COMP1)
Compensation pins of the error amplifiers.
Pin 7, 14: (BST2, BST1)
Supply pins for the high side drivers. Usually con-
nected to bootstrap circuit.
Pin 8, 13: (DH2, DH1)
Gate drive pins for the top MOSFETs. Requires a
small series resistor.
Pin 9, 12: (DL2, DL1)
Gate drive pins for the bottom MOSFETs. Requires a
small series resistor.
© 2004 Semtech Corp.
POWER MANAGEMENT
“+” input of the slave error amplifier.
“-” inputs of the error amplifiers.
Pin Configuration
Pin Descriptions
(TSSOP-20 Pin)
Top View
4
Notes:
(1) Only available in tape and reel packaging. A reel con-
tains 2500 devices.
(2) Lead free package.
Pin 10: (PGND)
Power GND. Return of the high side and low side gate
drivers.
Pin 11: (BSTC)
Supply pin for bottom MOSFET gate drivers.
Pin 17: (PHASING)
This pin controls the phase shift between master and
slave for optimum noise immunity. Use a resistive
divider from the FREQ pin (pin 2) to AGND, and
connect the tap of the resistive divider to pin 17.
Please see more information in Application section.
Pin 18: (SS/ENA)
Soft start pin. Connect a ceramic capacitor from this
pin to AGND, and there is an internal current source
charging up this capacitor during soft start. The PWM
operation can be disabled if this pin is pulled low.
Pin 19: (PWRGD)
Power good signal. This is an open collector output. It
is pulled low internally if output voltage is outside the
power good window.
Pin 20: (GND)
Analog GND. Return of the analog signals and bias of
the chip.
Ordering Information
S
S
S
S
C
C
C
C
2
D
2
2
6
2
6
e
6
7
6
7
v
7
7
7
7
c i
7
T
7
E
E
S
T
e
V
V
S
T
(
) 1
B
R
B
T
R
2 -
T
1 -
(
) 2
C
D
r u
u
l a
e r
t n
C
h
S
a
h
n
T
T
a
n
P
S
S
e r
l e
a
S
S
c
E
E
O
O
k
v
v
P
P
a
a
a
g
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SC2677
2 -
2 -
u l
u l
e
t a
0
0
t a
o i
o i
n
n
B
B
o
o
a
a
d r
d r