RT9245A
Multi-Phase PWM Controller for CPU Core Power Supply
General Description
RT9245A is a multi-phase buck DC/DC controller
integrated with all control functions for
AMD K8 CPU or
Intel
®
GHz CPU which is VRD10.x-compliant. The
RT9245A could be operated with 2, 3 or 4 buck switching
stages operating in interleaved phase set automatically.
The multiphase 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.
RT9245A implements both voltage and current loops to
achieve good regulation, response and power stage
thermal balance.
RT9245A applies the DCR sensing technology newly. The
RT9245A extracts the DCR of output inductor as sense
component to deliver a precise load line regulation and
good thermal balance for next generation processor
application.
Current sense setting, droop tuning, V
CORE
initial offset
and over current protection are independent
on
compensation circuit of voltage loop. The feature greatly
facilitates the flexibility of CPU power supply design and
tuning. The DAC output of RT9245A supports AMD K8
5-bit VID and Intel
®
VRD10.x with 6-bit VID input, precise
offset value & smooth V
CORE
transient at VID jump. The
IC monitors the V
CORE
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.
The RT9245A comes to a small footprint package
TSSOP-28.
Features
Multi-Phase Power Conversion with Automatic
Phase Selection
6-bits VRD10.x or 5-bit K8 DAC Output with Active
Droop Compensation for Fast Load Transient
Smooth V
CORE
Transition at VID Jump
Power Stage Thermal Balance by DCR Current
Sense
Hiccup Mode Over-Current Protection
Programmable Switching Frequency (50kHz to
400kHz per Phase), Under-Voltage Lockout and Soft-
Start
High Ripple Frequency Times Channel Number
28-TSSOP Package
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Intel
®
Processors Voltage Regulator : VRD10.x and AMD
K8
Low Output Voltage, High Current DC-DC Converters
Voltage Regulator Modules
Pin Configurations
(TOP VIEW)
VID4
VID3
VID2
VID1
VID0
VID125/VIDSEL
SGND
FB
COMP
PGOOD
DVD
SS
RT
VOSS
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VCC
PWM1
PWM2
PWM3
PWM4
CSP4
CSP2
CSP3
CSP1
GND
ADJ
IOUT
CSN
IMAX
Ordering Information
RT9245A
Package Type
C : TSSOP-28
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
TSSOP-28
Note :
RichTek Pb-free and Green products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
100% matte tin (Sn) plating.
www.richtek.com
1
DS9245A-05 March 2007
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
