SC2677B_09 Datasheet, PDF (1/19 Pages) Semtech Corporation – Dual Synchronous Voltage Mode Controller with Current Sharing Circuitry

SC2677B
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 pro-
duce a single output voltage from two separate input volt-
age 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 in-
put and output ripple.
Typical Application Schematic
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
PW RGD
D2
D1
C6
M1
C4
R5
CS1-
CS1+
R 50
M3
C 23
R51
C 63
L1
1
2
C19
Vout1
R8
Vin
ENABLE
C 28
R13
CS1+ CS1-
R19 ^U1
SC2677B
C 25
C 26
R14
C33
R 10
CS2+ CS2-
C36
C 39
C38
M5
C43
D3
C59
D4
R21
CS2-
CS2+
R 48
M7
R49
C 62
L2
1
2
C57
R 20
R 18
V out2
Revision: Dec. 04, 2009
Dual Independent outputs
1
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