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RT9199
Cost-Effective, 2A Peak Sink/Source Bus Termination Regulator
General Description Features
The RT9199 is a simple, cost-effective and high-speed Ideal for DDR-II VTT Applications
linear regulator designed to generate termination voltage Sink and Source 2A Peak Current
in double data rate (DDR) memory system to comply with Integrated Power MOSFETs
the devices requirements. The regulator is capable of Generate Termination Voltage for DDR Memory
actively sinking or sourcing up to 2A peak while regulating Interfaces
an output voltage to within 20mV. The output termination High Accuracy Output Voltage at Full-Load
voltage can be tightly regulated to track 1/2VDDQ by two Output Adjustment by Two External Resistors
external voltage divider resistors or the desired output Low External Component Count
voltage can be pro-grammed by externally forcing the Shutdown for Suspend to RAM (STR) Functionality
REFEN pin voltage. with High-Impedance Output
Current Limiting Protection
The RT9199 also incorporates a high-speed differential
On-Chip Thermal Protection
amplifier to provide ultra-fast response in line/load transient.
RoHS Compliant and 100% Lead (Pb)-Free
Other features include extremely low initial offset voltage,
excellent load regulation, current limiting in bi-directions
and on-chip thermal shut-down protection. Applications
Desktop PCs, Notebooks, and Workstations
The RT9199 are available in both SOP-8 and SOP-8
Graphics Card Memory Termination
(Exposed Pad) surface mount packages.
Set Top Boxes, Digital TVs, Printers
Embedded Systems
Ordering Information
Active Termination Buses
RT9199
Package Type DDR/II Memory Systems
S : SOP-8
SP : SOP-8 (Exposed Pad-Option 2)
Operating Temperature Range Pin Configurations
P : Pb Free with Commercial Standard (TOP VIEW)
G : Green (Halogen Free with Commer-
cial Standard)
VIN 8 VCNTL
Note : GND 2 7 VCNTL
REFEN 3 6 VCNTL
Richtek Pb-free and Green products are :
VOUT 4 5 VCNTL
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020. SOP-8
Suitable for use in SnPb or Pb-free soldering processes.
100%matte tin (Sn) plating. VIN 8 NC
GND 2 7 NC
GND
REFEN 3 6 VCNTL
9
VOUT 4 5 NC
SOP-8 (Exposed Pad)
DS9199-07 September 2007 www.richtek.com
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RT9199
Typical Application Circuit
VCNTL = 5V
VIN = 1.8V
RTT
R1 VIN VCNTL CIN CCNTL
RT9199
REFEN VOUT
2N7002
EN CSS
R2 GND
COUT RDUMMY
R1 = R2 = 100k, RTT = 50 / 33 / 25
COUT(MIN) = 10F (Ceramic) + 1000F under the worst case testing condition
RDUMMY = 1k as for VOUT discharge when VIN is not presented but VCNTL is presented
CSS = 1F, CIN = 470F (Low ESR), CCNTL = 47F
Test Circuit
VIN = 1.8V VCNTL = 5V
VIN VCNTL
RT9199 VOUT
1.25V REFEN VOUT
GND COUT V
IL
Figure 1. Output Voltage Tolerance, VLOAD
VCNTL = 5V
VIN = 1.8V A
VIN VCNTL
RT9199 0.9V
VOUT
0.9V REFEN VOUT
0V
GND COUT
0.15V RL V
RL and COUT
Time deleay
Figure 2. Current in Shutdown Mode, ISTBY
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RT9199
VIN = 1.8V VCNTL = 5V
VIN VCNTL
RT9199 VOUT
0.9V REFEN VOUT
GND A COUT V
IL
Figure 3. Current Limit for High Side, ILIM
Power Supply VCNTL = 5V
with Current Limit
VIN = 1.8V
A
VIN VCNTL
IL
RT9199 VOUT
0.9V REFEN VOUT
GND COUT V
Figure 4. Current Limit for Low Side, ILIM
VCNTL = 5V
VIN = 1.8V
VIN VCNTL
RT9199 VOUT
0.9V REFEN VOUT
VREFEN
0.15V GND RL COUT
V
0.9V
VOUT
0V
VOUT would be low if VREFEN < 0.15V
VOUT would be high if VREFEN > 0.6V
RL and COUT
Time deleay
Figure 5. REFEN Pin Shutdown Threshold, VIH & VIL
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RT9199
Functional Pin Description
VIN
Input voltage which supplies current to the output pin. Connect this pin to a well-decoupled supply voltage. To prevent the
input rail from dropping during large load transient, a large, low ESR capacitor is recommended to use. The capacitor
should be placed as close as possible to the VIN pin.
GND (Exposed Pad)
Common Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power
dissipation.
VCNTL
VCNTL supplies the internal control circuitry and provides the drive voltage. The driving capability of output current is
proportioned to the VCNTL. Connect this pin to 5V bias supply to handle large output current with at least 1F capacitor
from this pin to GND. An important note is that VIN should be kept lower or equal to VCNTL.
REFEN
Reference voltage input and active low shutdown control pin. Two resistors dividing down the VIN voltage on the pin to
create the regulated output voltage. Pulling the pin to ground turns off the device by an open-drain, such as 2N7002,
signal N-MOSFET.
VOUT
Regulator output. VOUT is regulated to REFEN voltage that is used to terminate the bus resistors. It is capable of sinking
and sourcing current while regulating the output rail. To maintain adequate large signal transient response, typical value
of 1000F Al electrolytic capacitor with 10F ceramic capacitors are recommended to reduce the effects of current
transients on VOUT.
Function Block Diagram
VCNTL VIN
Current Limit
Thermal Protection
+
REFEN
EA VOUT
-
GND
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RT9199
Absolute Maximum Ratings (Note 1)
Input Voltage, VIN ------------------------------------------------------------------------------------------------------ 6V
Control Voltage, VCNTL ----------------------------------------------------------------------------------------------- 6V
Power Dissipation, PD @ TA = 25