SC2545 Datasheet, PDF (1/24 Pages) Semtech Corporation – High Performance Wide Input Range Dual Synchronous Buck Controller

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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