RT9173/A
November, 2000
3A Bus Termination Regulator
General Description
The RT9173/A regulator is designed to convert
voltage supplies ranging from 1.8V to 6V into a
desired output voltage which adjusted by two
external resistors, voltage divider. The regulator
is capable of sourcing or sinking up to 3A of
current while regulating an output voltage to
within 2% or less.
The RT9173/A, used in conjunction with series
termination resistors, provides an excellent
voltage source for active termination schemes of
high speed transmission lines as those seen in
high speed memory buses and distributed
backplane designs. The voltage output of the
regulator can be used as a termination voltage
for DDR.
Features
•
•
•
•
•
•
•
•
•
•
Power TO-263-5 Package.
Capable of Sourcing and Sinking Current 3A
Current-limiting Protection
Thermal Protection
Integrated Power MOSFETs.
Generates Termination Voltages for SSTL-2
High Accuracy Output Voltage at Full-load
Adjustable VOUT by External Resistors
Minimum External Components
Shutdown for Standby or Suspend Mode
Operation with High-impedance Output
•
Soft-start Function
Applications
•
•
•
•
Computers
Disk Drives
CD-ROM
Supply Splitter
Ordering Information
RT9173/A
Package type
M5: TO-263-5
Operation temperature range
C: Commercial standard
3A sink & source
1A sink & source
Pin Configuration
Part Number
RT9173/ACM5
(Plastic TO-263-5)
Pin Configuration
Pin Name
1
VIN
MARK
2
GND
3 VCNTL
4 REFEN
12 3 4 5
5 VOUT
Absolute Maximum Ratings
•
•
•
•
•
•
Input Voltage Range
Power Dissipation
ESD Rating
Storage Temperature Range
Lead Temperature (Soldering, 5 seconds)
Package Thermal Resistance
TO-263 (θ
JC
)
7V
Internally Limited
3KV
-50°C to 150°C
260°C
2°C/W
RichTek Technology Corp.
6F, No. 35, Hsintai Road, Chupei City, Hsinchu, Taiwan, R.O.C.
-- 1 / 5 --
DS9173/A-00
Tel: (8863) 5510047 Fax: (8863) 5537749
RT9173/A
November, 2000
Electrical Characteristics
Limits in standard typeface are for T
J
= 25°C, unless otherwise specified:
VIN = 2.5V, VCNTL = 3.3V, V
REFEN
= 1.25V, C
OUT
= 10µF (Ceramic)
Parameter
Output Offset Voltage, V
OS
Load Regulation,
∆V
OUT
VIN
Input Voltage Range
VCNTL
Current In Shutdown Mode, I
SHDN
RT9173
Peak Output Current
RT9173A
Short Circuit Protection
RT9173
Current Limit, I
CL
RT9173A
Over Temperature Protection
Shutdown Threshold
Thermal Shutdown Hysteresis
Shutdown Function
Shutdown threshold trigger
Min. Typ. Max. Units
Figure 1.
-15
0
15 mV
I
L
: -3A 3A, Figure 1.
-2
0
+2
%
1.8 2.5
6
V
Keep VCNTL
≥
VIN in operation
power on and power off sequences
3.3
6
V
V
REFEN
<
0.4V, RL = 10KΩ, Figure 2.
30
60
µA
1.5
3
A
3.5
5
Figure 3,4
Figure 3,4
1.5
3.5
2
4
150
50
0.8
0.4
Test Conditions
A
Guaranteed by design
°C
°C
Output = High, Figure 5
Output = Low, Figure 5
V
Function Block Diagram
VCNTL
VIN
Current
Limiting Sensor
EN
Thermal
CNTL
VOUT
GND
Pin Description
Pin Name
VIN
GND
VCNTL
REFEN
VOUT
Pin Function
Input Supply
Ground
Gate Drive Voltage
Reference Voltage Input and Chip Enable
Output Voltage (equals to ½ VIN if R
1
= R
2
.)
DS9173/A-00
Tel: (8863) 5510047 Fax: (8863) 5537749
RichTek Technology Corp.
6F, No. 35, Hsintai Road, Chupei City, Hsinchu, Taiwan, R.O.C.
-- 2 / 5 --
RT9173/A
Typical Applications
V
CNTL
= 3.3V
V
IN
= 2.5V
R
1
VIN
REFEN
EN
Q1
R
2
VCNTL
C
IN
C
CNTL
R
TT
November, 2000
RT9173/A
GND
VOUT
C
SS
C
OUT
R
1
= R
2
= 100KΩ, R
TT
= 50Ω / 33Ω / 25Ω
C
OUT
,
min
= 10µF (ceramic), C
SS
= 1µF, C
IN
= 100µF, C
CNTL
= 47µF
Test Circuits
2.5V
3.3V
VIN
1.25V
REFEN
VCNTL
RT9173/A
GND
VOUT
V
OUT
V
I
L
C
OUT
Figure 1: Output Voltage Tolerance,
∆
V
OUT
3.3V
2.5V
A
VIN
1.25V
0.4V
REFEN
VCNTL
VOUT
R
L
V
OUT
V
RT9173/A
GND
1.25V
0V
C
OUT
R
L
and C
OUT
Time delay
Figure 2: Current in Shutdown Mode, I
shcln
RichTek Technology Corp.
6F, No. 35, Hsintai Road, Chupei City, Hsinchu, Taiwan, R.O.C.
-- 3 / 5 --
DS9173/A-00
Tel: (8863) 5510047 Fax: (8863) 5537749
RT9173/A
November, 2000
2.5V
3.3V
VIN
1.25V
REFEN
VCNTL
VOUT
A
RT9173/A
GND
V
OUT
V
I
L
C
OUT
Figure 3: Current Limit for High Side, I
CLHIGH
Power supply
with current limit
2.5V
VIN
1.25V
REFEN
3.3V
VCNTL
VOUT
A
I
L
V
OUT
V
RT9173/A
GND
C
OUT
Figure 4: Current Limit for Low Side, I
CLLOW
2.5V
VIN
1.25V
V
REFEN
0.2V
REFEN
3.3V
VCNTL
VOUT
R
L
V
OUT
V
RT9173/A
GND
1.25V
V
OUT
0V
V
OUT
would be low if VREFEN < 0.4V
V
OUT
would be high if VREFEN > 0.8V
R
L
and C
OUT
Time delay
C
OUT
Figure 5: REFEN Pin Shutdown Threshold, V
trigger
RichTek Technology Corp.
6F, No. 35, Hsintai Road, Chupei City, Hsinchu, Taiwan, R.O.C.
-- 4 / 5 --
DS9173/A-00
Tel: (8863) 5510047 Fax: (8863) 5537749
RT9173/A
Package Information
November, 2000
D
B
E
MARK
A
C
L1
L2
e
1 2
3
4
5
b
b2
Symbol
D
B
E
A
C
L1
L2
b
b2
e
Dimensions In Inches
Min
Norm
Max
0.3921
0.0783
0.3307
0.1724
0.0465
0.1169
0.0602
0.0280
0.0110
--
0.4000
0.0862
0.3386
0.1803
0.0504
0.1248
0.0681
0.0319
0.0150
0.0669
0.4079
0.0941
0.3465
0.1882
0.0543
0.1327
0.0760
0.0358
0.0189
--
Dimensions In Millimeters
Min
Norm
Max
9.96
1.99
8.40
4.38
1.18
2.97
1.53
0.71
0.28
--
10.16
2.19
8.60
4.58
1.28
3.17
1.73
0.81
0.38
1.70
10.36
2.39
8.80
4.78
1.38
3.37
1.93
0.91
0.48
--
5-Lead TO-263 Plastic Surface Mount Package
RichTek Technology Corp.
6F, No. 35, Hsintai Road, Chupei City, Hsinchu, Taiwan, R.O.C.
-- 5 / 5 --
DS9173/A-00
Tel: (8863) 5510047 Fax: (8863) 5537749
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