RT8207
Complete DDRII/DDRIII Memory Power Supply Controller
General Description
Features
z PWM Controller
The RT8207 provides a complete power supply for both
DDRII/DDRIII memory systems. It integrates a
synchronous PWM buck controller with a 3A sink/source
tracking linear regulator and a buffered low noise reference.
` Resistor Programmable Current Limit by Low-Side
RDS(ON) Sense
` Quick Load-Step Response within 100ns
` 1% VOUT Accuracy Over Line and Load
` Fixed 1.8V (DDRII), 1.5V (DDRIII) or Adjustable
0.75V to 3.3V Output Range
The PWM controller provides the high efficiency, excellent
transient response, and highDC output accuracy needed
for stepping down high-voltage batteries to generate low
voltage chipset RAM supplies in notebook computers.
The constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides 100ns
“instant-on” response to load transients while maintaining
a relatively constant switching frequency.
` Battery Input Range 2.5V to 26V
` Resistor Programmable Frequency
` Over/Under Voltage Protection
` 4 Steps Current Limit During Soft-Start
` Drives Large Synchronous-Rectifier FETs
` Power-Good Indicator
The RT8207 achieves high efficiency at a reduced cost
by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous
rectifier MOSFETs. The buck conversion allows this device
to directly step down high-voltage batteries for the highest
possible efficiency.
z 3A LDO (VTT), Buffered Reference (VTTREF)
` Capable to Sink and Source Up to 3A
` LDO Input Available to Optimize Power Losses
` Requires Only 20μF Ceramic Output Capacitor
` Buffered Low Noise 10mA VTTREF Output
` Accuracy 20mV for Both VTTREF and VTT
` Supports High-Z in S3 and Soft-Off in S4/S5
z RoHS Compliant and Halogen Free
The 3Asink/source LDO maintains fast transient response
only requiring 20μF of ceramic output capacitance. In
addition, the LDO supply input is available externally to
significantly reduce the total power losses. The RT8207
supports all of the sleep state controls placing VTT at
High-Z in S3 and discharging VDDQ, VTT and VTTREF
(soft-off) in S4/S5.
Applications
z DDRII/DDRIII Memory Power Supplies
z Notebook Computers
z SSTL18, SSTL15 and HSTL Bus Termination
The RT8207 has all of the protection features including
thermal shutdown and is available in the WQFN-24L 4x4
package.
Pin Configurations
(TOP VIEW)
Ordering Information
RT8207
24 23 22 21 20 19
1
2
3
18
17
16
VTTGND
VTTSNS
GND
PGND
NC
CS
Package Type
QW : WQFN-24L 4x4 (W-Type)
GND
4
5
6
15
14
13
MODE
VTTREF
DEM
VDDP
VDD
PGOOD
25
Lead Plating System
7
8
9 10 11 12
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
WQFN-24L 4x4
` 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.
DS8207-07 March 2011
www.richtek.com
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