AME, Inc.
AT9173
Bus Termination Regulator
n
General Description
The AT9173 is a voltage regulator which could
convert the input voltage ranging from 1.8V to 5V to an
output voltage that user settled. The regulator can
provide sourcing or sinking current.The AT9173, 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 SDRAM.
Current limits in both sourcing and sinking mode, plus
on-chip thermal shutdown make the circuit tolerant of
the output fault conditions.
n
Features
●
Support
Both DDR I (1.25VTT) and DDR II
of Sourcing and Sinking Current
(0.9VTT) Requirements
●
Capable
●
●
Current-limiting Protection
Thermal Protection
Power MOSFETs
Termination Voltages for SSTL-2
●
Integrated
●
Generates
●
High
●
●
Accuracy Output Voltage at Full-Load
Adjustable V
OUT
by External Resistors
Minimum External Components
for Standby or Suspend Mode
Operation with High-impedance Output
●
Shutdown
n
Applications
●
DDRI/DDRII
●
●
●
Memory Termination Supply
Active Termination Buses
Desktop PC,NoTebook,Server and workstation
Graphic Card
Top Box
Embedded System
●
Set
●
n
Typical Application
DDR _2.5 V
AT9173 A-SOP 8
VCC_ 3.3 V
1
R2
100KO
C4
0.1 uF
C2
470uF
2
3
4
VIN
GND
REFEN
VOUT
VCNTL
VCNTL
8
7
VCNTL
VCNTL
6
5
DDR_VTT
1.25V/1.5A
R4
100KO
AT9173A
SOP-8
C8
4.7uF
C6
470uF
Rev. C.04
1
AME, Inc.
AT9173
Bus Termination Regulator
n
Typical Application(Contd.)
VCC_ 3.3V
DDR_2.5V
AT9173 E-SOP 8 / PP
VIN
1
NC
GND _PAD
NC
VCNTL
NC
5
8
7
6
DDR_ VTT
1 .25V/2A
R1
100 KO
C3
0.1uF
C4
470uF
GND
2
REFEN
3
4
VOUTL
R3
100KO
AT9173E
SOP-8/PP
C7
4.7uF
C5
470uF
n
Function Block Diagram
VCNTL
VIN
Thermal
Sensor
+
-
Thermal
&
Over Current
Protection Circuit
REFEN
+
-
GND
VOUT
VCNTL
2
Rev. C.04
AME, Inc.
AT9173
Bus Termination Regulator
n
Pin Configuration
SOP- 8
Top View
8
7
6
5
SOP- 8/PP
Top View
AT9173A
1. IN
2. GND
3. REFEN
4. OUT
5. VCNTL
6. VCNTL
7. VCNTL
8. VCNTL
8
7
6
5
AT9173
1
2
3
4
AT9173
1
2
3
4
AT9173E
1. IN
2. GND
3. REFEN
4. OUT
5. NC
6. VCNTL
7. NC
8. NC
n
Pin Description
Pin name
Pin Description
Input voltage pin which supplies current to the V
OUT
pin. Connect this pin to a well-
decoupled voltage to prevent the input rail from dropping during large load transient. A
large and low ESR capacitor is recommended to use that should be placed as close as
possible to the V
IN
pin.
Ground pin. Tie directly to ground plance.
Voltage control pin which 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 1uF capacitor from
this pin to GND. An important note is that V
IN
should be kept lower or equal to VCNTL.
Reference voltage input and active low shutdown control pin. Two resistors dividing
down the V
IN
voltage on this pin to create the regulatedoutput voltage. Pulling this pin to
GND to turn off the device by an open-drain, such as 2N7002 N-Channel MOSFET.
Regulator output. V
OUT
is regulated from 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 1000uF
electrolytic capacitor with 10uF ceramic capacitors are recommended to reduce the
effects of current transients on V
OUT
.
No Connection. Not internal connected.
Connected to GND plance for better heat dissipation.
IN
GND
VCNTL
REFEN
OUT
NC*
GND Pad*
* By SOP-8/PP only
Rev. C.04
3
AME, Inc.
AT9173
Bus Termination Regulator
n
Ordering Information
Part Number
AT9173AG
Marking
AT9173AG
yyww* AB
xxxxxxx##**
AT9173EG
yyww* AC
xxxxxxx##**
Output Voltage
ADJ
Package
SOP-8
Operating Temp. Range
-25 C to +85 C
AT9173EG
ADJ
SOP-8/PP
o
o
Note:
* yy and ww represents the data code.
** XXXXXXX represents the wafer lot number, ## represents the wafer number
4
Rev. C.04
AME, Inc.
AT9173
Bus Termination Regulator
n
Absolute Maximum Ratings
Parameter
Input Voltage. V
IN
to GND
VCNTL to GND
ESD Rating (Human Body Mode)
Storage Temperature
Lead Temperature (Soldering. 5sec)
Symbol
V
IN
V
CNTL
V
ESD
T
STG
TL
Maximum
6
6
2
150
245
Unit
V
V
KV
O
O
C
C
n
Recommended Operating Conditions
Parameter
Supply Voltage 1
Supply Voltage 2
Output Current of V
OUT
Pin *
Junction Temperature
Symbol
V
IN
V
CNTL
*I
OUT
T
J
Rating
1.8 or 2.5
3.3
-2 to 2
-25 to 125
Unit
V
V
A
O
C
*The symbol "+" means the VOUT sources current to load; the symbol "-" means the VOUT
sinks current to GND
n
Thermal Characteristics
Parameter
Thermal Resistance*
(Junction to Case)
Package
SOP-8
SOP-8/PP
SOP-8
SOP-8/PP
SOP-8
Die Attch
Non-Conductive
Epoxy
Conductive
Epoxy
Non-Conductive
Epoxy
Conductive
Epoxy
Non-Conductive
Epoxy
Conductive
Epoxy
Symbol Maximum
55
θ
JC
19
Unit
O
C/W
Thermal Resistance
(Junction to Ambient)
120
θ
JA
84
1300
P
D
1450
mW
Internal Power Dissipation
SOP-8/PP
Rev. C.04
5
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