CS5127 Datasheet, PDF (1/24 Pages) Cherry Semiconductor Corporation – Dual Output Nonsynchronous Buck Controller with Sync Function and Second Channel Enable

CS5127
Dual Output Nonsynchronous Buck Controller
with Sync Function and Second Channel Enable
Description
Features
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^2ª 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.
s Nonsynchronous Buck
Design
s V^2ª 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
+ _{C1, C2}
2 x 680mF
R1
20k
C6
0.1mF
2.8V
R4
1540
C7
330pF
R2
27k
L1
+
5mH
C10, C11
2 x 680mF
Q2
IRL3103S
D1
1N5821
R5
1270
R6
R10
1k
20k
C14
330pF
C3 ₊
1mF
12V
+5V
C4, C5 +
2 x 680mF
SYNC
VIN
CS5127
CT
VREF
RT
ENABLE
VFB1
VFB2
COMP1
COMP2
VFFB1
VFFB2
GATE1
GATE2
LGnd
PGnd
+ _C8
1mF
C9
0.1mF
Q3
IRL3103S
D2
1N5821
L2
5mH
C12, C13 ⁺
2 x 680mF
C15
100mF
C16
100mF
R11
20k
C17
330pF
3.3V
R9
2k
R7
2400
R3
18k
R8
1500
Package Option
16 Lead SOIC Wide
SYNC ¹
C_T
R_T
V_FB1
COMP1
V_FFB1
GATE1
LGND
V_IN
V_REF
ENABLE
V_FB2
COMP2
V_FFB2
GATE2
PGND
V² is a trademark of Switch Power, Inc.
Pentium is a registered trademark and MMX is a trademark of Intel Corporation
Rev. 11/3/98
1
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: [phone] Fax: [phone]
Email: [e-mail]
Web Site: www.cherry-semi.com
A
¨ Company