Dual Synchronous Voltage Mode
Controller with Current Sharing Circuitry
POWER MANAGEMENT
Description
The SC2677B is a versatile 2 phase, synchronous, voltage
mode PWM controller that can be used in two distinct ways.
First, the SC2677B is ideal for applications where point of
use output power exceeds any single input power budget.
Alternatively, the SC2677B can be configured as a dual
switcher. The SC2677B features a precise temperature
compensated voltage reference, cycle-by-cycle peak cur-
rent limit, under voltage lockout over current protection,
and internal level-shifted high-side gate drive circuitry.
In current sharing configuration, the SC2677B can produce
a single output voltage from two separate input voltage
sources (which can be different in voltage levels) while
maintaining current sharing between the two channels.
Current sharing is programmable to allow each input sup-
ply to be loaded differently per application requirements.
In dual switcher configuration, two feedback paths are pro-
vided for independent control of the separate outputs. The
device will provide a regulated output from flexibly config-
ured inputs, such as 3.3V, 5V, 12V etc. The phasing be-
tween the two switchers is adjustable to minimize the input
and output ripple.
SC2677B
Features
300kHz to 1MHz externally programmable
frequency operation
Soft Start and Enable function
Power Good output provided
Cycle-by-cycle peak current limit
Latch Off for over current protection
Phase-shifted switchers minimize ripple
High-efficiency operation, >90%
Programmable output(s) as low as 0.5V
Industrial temperature range
TSSOP-24 package
TSSOP-24 EDP package
Bias voltage as low as 4.5V
Adjustable phase shift between channels
Two Phase, Current Sharing Controller
Flexible, same or separate V
IN
Programmable current sharing
Thermal distribution via multi-phase output
Applications
Graphics cards
Peripheral add-in card
Dual-phase power supply
Power supplies requiring two outputs
CS1-
CS1+
C63
R51
Typical Application Schematic
D2
D1
C6
R50
M1
C4
M3
L1
1
2
Vout1
R5
C19
C23
R8
PW RGD
ENABLE
CS1+ CS1-
C28
R13
C26
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
C25
R14
R10
P S
HA ING
P RG
W D
S /E
S NA
C 1
S+
G
ND
CO P
M 1
Vin
R19
U1
FRE
Q
V F
RE
C 2
S+
C 2
S-
SC2677B
CO P
M 2
P ND
G
B T2
S
+
IN2
V
CC
DH2
-IN2
D2
L
C33
1
0
1
1
1
2
1
2
3
4
5
6
7
8
9
B TC
S
B T1
S
-IN1
DH1
C 1
S-
D1
L
R21
CS2+ CS2-
C36
R20
CS2-
C39
C38
CS2+
R49
C62
R18
R48
L2
1
M5
C43
D3
D4
C59
M7
C57
2
Vout2
Dual Independent outputs
Revision: Dec. 15, 2004
1
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