High Performance Synchronous Buck
Controller With Reference Tracking
POWER MANAGEMENT
Description
The SC4510 can be configured as a synchronous buck
convertor capable of sourcing and sinking current from load
without losing output regulation. The output can be set to
track an internal reference or an external voltage. The
actual reference used by the error amplifier is buffered
and brought out as a reference. It is the ideal choice for
externally referenced or tracking buck convertors such as
those for DDR memory applications.
The controller is also designed for point of use DC-DC
convertors with 2.5-16V power sources with a Vcc of 4.5V
or higher. Soft start, current limit, programmable oscillator
and external compensation functions are provided to
ensure high degree of integration and low external
component count. Semetch’s patented Combi-Sense™
technique is utilised for lossless current sening and
maximising efficiency. Both high and low side MOSFET
drivers are built in and rated for substantial peak currents
to minimise switching losses. The SC4510 is offered in a
space saving TSSOP-20 package.
SC4510
Features
u
Synchronous buck operation with current sink or
u
u
u
u
u
u
u
u
u
source without loss of regulation
Output can track internal or external reference
Buffered reference output from external reference
Combi-Sense mode lossless current sensing
2.5V to 16V operation with 4.75V minimum V
CC
Direct drive for high side N-channel MOSFETs with
diode and capacitor bootstrap
Undervoltage lockout, Soft Start, Enable and Power
Good functions
Fast transient response with external compensation
Current mode control with transconductance error
amplifier
Programmable oscillator frequency with external sync
Applications
u
Externally referenced buck convertors
u
DDR memory terminators
u
Point of use power supplies
Typical Application Circuit
VIN
15V MAX
C1
C2
D1
Q1
R1
L1
C3
RTN
VOUT
0.5V MIN
Q2
C4
C5
R2
R3
C6
R4
C7
SYNC
20
19
18
17
16
15
14
13
12
11
RTN
SS/EN
VPN
BST
IN-
VIN
AGND
SYNC
COMP
ROSC
GDH
R5
REFOUT
SC4510
PGOOD
AVCC
PVCC
CS+
CS-
U1
PGND
GDL
R6
R7
REF
C8
REFIN
10
1
2
3
4
5
6
7
8
9
PGOOD
INT REF
IN+
C9
REFOUT
EXT REF
C10
C11
C12
C13
Revision: Jan 07, 2005
United States Patent #6,441,597
1
www.semtech.com
SEMTECH [ SEMTECH CORPORATION ]
