SC2545
High Performance Wide Input Range
Dual Synchronous Buck Controller
POWER MANAGEMENT
Description
Features
The SC2545 is a high performance dual PWM controller.
It is designed to convert a wide ranged input voltage down
to two independent output rails. The SC2545 support
“peel off ” tracking for the two outputs at start up which
means the two outputs ramp up together till the one
with lower output level reaching the regulation. The PWM
operations of the two channels are 180 degree out of
phase which can greatly reduce the size and the cost of
the input capacitors. Synchronous Buck PWM topology
and voltage mode control allow high efficiency operation,
fast transient responses, and flexible component selec-
tion for easy designs. A 10V internal linear regulator pro-
vides the bias for the controller, and this voltage is opti-
mized for gate drivers to deliver high efficiency. The power
sequencing is fully supported including independent start
up, and power good output. In the shut down mode the
controller only draws 100nA from the supply. The con-
troller also offers full protection features for the condi-
tions of under voltage, over voltage, and the over current.
There is no need for a current sensing resistor because
the MOSFET on resistance is used for the sensing
element. The switching frequency is adjustable from 100
kHz to 300 kHz. Two packages TSSOP-24 and MLPQ-24
are offered.
Typical Application Circuit
Independent dual-outputs
“Peel off “start up trackingIndependent dual-outputs
Wide input voltage range: 4.5V~28V
Adjustable output voltage down to 0.75V
Flexible power sequencing with enable and power
good output
Synchronous Buck topology with voltage mode
control
Out of phase operation to reduce cost of input
capacitor
10V internal regulator for gate driver to deliver high
efficiency
Programmable switching frequency:
100kHz~300kHz
Full protection: UVLO, OVP and programmable
OCP
No need for current sense resistor
Low shutdown current (100nA typical)
24 lead TSSOP and MLPQ packages
Fully WEEE and RoHS Compliant
Applications
Systems with 4.5V~28V input
LCDTV and PDPTV
Network and telecom systems
ENABLE
FB1
VIN+
VO1
FB1
VIN+
VC C
SC2545
1 VIN
AGND 24
2 VCC
ROSC 23
3 EN
PWRGD 22
4 FB1
FB2 21
5 ERROUT1 ERROUT2 20
6
SS1
19
SS2
7 ILIM1
ILIM2 18
8
BST1
17
BST2
9 DRVH1
DRVH2 16
10 PHASE1
PHASE2 15
11 DRVL1
DRVL2 14
12 PGND
PVCC 13
VCC
VO1
VIN+
PWGRD
FB2
VO2
FB2
Revision: August 10, 2005
Pinout shown as TSSOP-24.
1
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