CS5127
CS5127
Dual Output Nonsynchronous Buck Controller
with Sync Function and Second Channel Enable
Description
The CS5127 is a fixed frequency
dual output nonsynchronous buck
controller. It contains circuitry for
regulating two separate outputs.
Each output channel contains a
high gain error amplifier, a com-
parator and latch, and a totem-pole
output driver capable of providing
DC current of 100mA and peak cur-
rent in excess of 0.5A. A common
oscillator controls switching for
both channels, and a sync lead is
provided to allow parallel supply
operation or shifting of the switch-
ing noise spectrum. An on-chip 5V
reference is capable of providing as
much as 10mA of current for exter-
nal circuitry. The CS5127 also
contains two undervoltage lockout
circuits. The first lockout releases
when V
IN
reaches 8.4V, while the
second lockout ensures that V
REF
is
higher than 3.6V. The outputs are
held in a low state until both lock-
outs have released. The controller is
configured to utilize the V
2
ª con-
trol method to achieve the fastest
possible transient response and
best overall regulation. This dual
controller is a cost-effective solu-
tion for providing V
CORE
and V
IO
power solutions in computing
applications using a single con-
troller. The CS5127 will operate
over an input voltage range of 9.4V
to 20V and is available in a 16 lead
wide body surface mount package.
Features
s
Nonsynchronous Buck
Design
s
V
2
ª Control Topology
s
100ns Transient Loop
Response
s
Programmable Oscillator
Frequency
s
30ns Typical Gate Rise
and 10ns Fall Times
(No Load)
s
Frequency
Synchronization Input
s
ENABLE Input Controls
Channel 2 Gate Driver
s
5V/10mA Reference
Output
Applications Diagram
12V, 5V to 2.8V @ 7A and 3.3V @ 7A for 233MHz Pentium
¨
Processor with MMXª Technology
5V
+
Q1
FMMT2222ACT
SYNC
C
T
V
IN
V
REF
Package Option
+5V
12V
C3 +
1mF
16 Lead SOIC Wide
SYNC
C
T
1
C1, C2
2 x 680mF
C4, C5
2 x 680mF
+
V
IN
V
REF
ENABLE
V
FB2
COMP2
V
FFB2
GATE2
PGND
CS5127
R
T
C9
0.1mF
+ C8
1mF
Q3
IRL3103S
D2
1N5821
R1
20k
C6
0.1mF
R
T
ENABLE
V
FB2
COMP2
V
FFB2
GATE2
PGnd
V
FB1
COMP1
C7
330pF
R2
27k
L1
Q2
IRL3103S
D1
1N5821
V
FB1
COMP1
V
FFB1
GATE1
LGnd
L2
5mH
C12, C13
2 x 680mF
+
3.3V
R7
2400
R8
1500
V
FFB1
GATE1
LGND
2.8V
+
R4
1540
5mH
C10, C11
2 x 680mF
R9
2k
R3
18k
R5
1270
R10
20k
R6
1k
C14
330pF
C15
100mF
C16
100mF
C17
330pF
R11
20k
V
2
is a trademark of Switch Power, Inc.
Pentium is a registered trademark and MMX is a trademark of Intel Corporation
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
Rev. 11/3/98
1
A
¨
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
