Preliminary
RT9237
Multi-Phase DC/DC Controller for CPU Core Power Supply
General Description
The RT9237 is a multi-phase buck DC/DC controller
integrated
with
all control functions
for
high
performance processor VRM. The RT9237 drives 2,
3 or 4 buck switching stages operating in interleaved
phase
set
automatically.
The
multi-phase
architecture provides high output current while
maintaining low power dissipation on power devices
and low stress on input and output capacitors. The
high equivalent operating frequency also reduces
the component dimension and the output voltage
ripple in load transient.
RT9237 regulates both easily set voltage and
current loops. Precise current sharing for power
stage is achieved by differential input current sense
and processing circuit. The settings of current
sense, droop tuning and over current protection are
independent to compensation circuit of voltage loop.
The feature greatly facilitates the flexibility of CPU
power supply design and tuning.
The RT9237 uses a 5-bit DAC of 1.1V to 1.85V
(25mV/step)
output
with
load
current
droop
compensation to meet the strict VRM transient
requirement. The IC monitors the VCORE voltage
for PGOOD and over voltage protection. Soft start,
over current protection and programmable under
voltage lockout are also provided to assure the
safety of microprocessor and power system.
Features
Multi-Phase Power Conversion with Automatic
Phase Selection
VRM 9.0 DAC Output with Active Droop
Compensation for Fast Load Transient
Precise
Channel
Current
Sharing
with
Differential Sense Input
Hiccup Mode Over Current Protection
Programmable Under Voltage Lockout and
Soft Start
High Ripple Frequency, (Channel Frequency
200KHz) Times Channel Number
Pin Configurations
Part Number
RT9237CS
(Plastic SOP-28)
VID4
VID3
VID2
VID1
VID0
COMP
FB
ADJ
GND
1
2
3
4
5
6
7
8
9
Pin Configurations
TOP VIEW
VDD
PGOOD
26
PWM4
28
27
25
24
23
ISP4
ISP1
PWM1
22
PWM2
21
ISP2
20
ISP3
PWM3
ISN1
17
ISN2
19
18
16
15
VSEN
10
IRMP
11
DVD
12
IMAX
13
SS
14
ISN3
ISN4
Applications
Power Supply for Server and Workstation
Power Supply for High Current Microprocessor
Ordering Information
RT9237
Package Type
S : SOP-28
Operating temperature range
C: Commercial standard
DS9237-00 January 2002
www.richtek-ic.com.tw
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