Advanced Power
Electronics Corp. AP1280AGN
3
2A SINK/SOURCE BUS TERMINATION REGULATOR
FEATURES DESCRIPTIOON
Ideal for DDR-I, DDR-II and DDR-III VTT Applications
Sink and Source up to 2Amp
Integrated Power MOSFETs
Generates Termination Voltage for SSTL_2, SSTL_18,
HSTL, SCSI-2 and SCSI-3 Interfaces.
High Accuracy Output Voltage at Full-Load
Output Adjustment by Two External Resistors
Built-in Soft-start Function
Shutdown for Suspend to RAM (STR) Functionality
with High-Impedance Output
Current Limiting Protection
On-Chip Thermal Protection
Available in DFN 3x3-8L Packages
VIN and VCNTL Under Voltage Protection
RoHS Compliant and 100% Lead (Pb)-Free
APPLICATION
Desktop PCs, Notebooks, and Workstations
Graphics Card Memory Termination
Set Top Boxes, Digital TVs, Printers
Embedded Systems
Active Termination Buses
DDR-I, DDR-II and DDR-III Memory Systems
Data and specifications subject to change without notice
201205172FC
TYPICAL APPLICATION
1
The AP1280AGN3 is a simple, cost-effective and
high-speed linear regulator designed to generate
termination voltage in double data rate (DDR) memory
system to comply with the JEDEC SSTL_2 and
SSTL_18 or other specific interfaces such as HSTL,
SCSI-2 and SCSI-3 etc. devices requirements. The
regulator is capable of actively sinking or sourcing up to
2A while regulating an output voltage to within 40mV.
The output termination voltage cab be tightly regulated
to track 1/2VDDQ by two external voltage divider resistors
or the desired output voltage can be pro-grammed by
externally forcing the REFEN pin voltage.
The AP1280AGN3 also incorporates a high-speed
differential amplifier to provide ultra-fast response in
line/load transient. Other features include extremely low
initial offset voltage, excellent load regulation, current
limiting in bi-directions and on-chip thermal shut-down
protection.Built-in softstart function avoids a
misoperation by inrush current.
The AP1280AGN3 are available in the DFN 3x3-8L
surface mount packages.
VIN
Shutdown
Enable
VCNTL
VOUT
VIN
REFEN
VCNTL
VOUT
GND
R1
R2 CSS
CIN CCNTL
COUT RDUMMY
RTT
AP1280AGN3
R1 = R2 = 100K, RTT = 50/ 33/ 25
COUT = 10uF ( + 100 uF under the worst case testing condition )
CSS = 1uF , CIN = 470uF (Low ESR) , CCNTL = 47uF
Advanced Power
Electronics Corp. AP1280AGN
3
ABSOLUTE MAXIMUM RATINGS
(Note1)
Input Voltage (VIN) -----------------------------------------
-
6V
CNTL Pin Voltage (VCNTL) -------------------------------
-
6V
Power Dissipation (PD) -----------------------------------
-
Internally Limited
Storage Temperature Range (TST) --------------------
-
-65 to +150°C
Lead Temperature (Soldering, 10sec.) --------------- 260°C
40°C/W
Note1 : Exceeding the absolute maximum rating may damage the device.
OPERATING RATING(Note2)
Input Voltage (VIN) -----------------------------------------
-
2.5V to 1.5V +3%
CNTL Pin Voltage (VCNTL) -------------------------------
-
5.5V or 3.3V +5%
Junction Temperature Range (TJ) --------------------- -40 to +125°C
Ambient Temperature Range (TA) --------------------- -40 to +85°C
Note2 : The device is not guaranteed to function outside its operating conditions.
ORDERING / PACKAGE INFORMATION
(VIN=1.8V/1.5V, VCNTL=5V, VREFEN=0.9V/0.75V, COUT=10uF(Ceramic), T
A
=25oC, unless otherwise specified)
Parameter SYM TEST CONDITION MIN TYP MAX UNITS
VCNTL Operation Current ICNTL IOUT = 0A - 1 2.5 mA
Standby Current ISTBY VREFEN= 0V (Shutdown) - 25
uA
VIN Shutdown Current IVIN VREFEN= 0V (Shutdown) - - 5uA
VCNTL UVP Rising Threshold VCOP VCNTL Rising 2.4 2.55 2.7 V
VCNTL UVP Hysteresis VCHYS -0.35 -V
VIN UVP Rising Threshold VIOP VIOP Rising 0.8 0.95 1.1 V
VIN UVP Hysteresis VIHYS -0.15 -V
IOUT = 10mA -13 - 13
IOUT = -10mA -13 - 13
IOUT = 10mA ~ 2A -13 - 13
IOUT = -10mA ~ -2A -13 - 13
ELECTRICAL SPECIFICATIONS
Input
2
Thermal Resistance from Junction to Case (Rthjc)
Output (DDR / DDRII / DDRIII)
Load Regulation(Note4) ΔVLoad
mV
UVP Function
Output Offset Voltage(Note3) ΔVOS
Rth
j
a = 150oC/W
AP1280 AX-HF
Package Type
Halogen-Free
GN3 : DFN 3x3-8L
( Top View )
DFN 3x3-8L
GND
VIN 1
2
3
45
6
7
8
GND
REFEN
VOUT NC
VCNTL
NC
NC
Advanced Power
Electronics Corp. AP1280AGN
3
Parameter SYM TEST CONDITION MIN TYP MAX UNITS
Current Limit ILIM 2.2 - - A
Thermal Shutdown Temperature TSD 3.3V < VCNTL < 5V - 150 -
Thermal Shutdown Hysteresis ΔTSD 3.3V < VCNTL < 5V - 20 -
REFEN Threshold VEN 0.15 - 0.4 V
Soft-Start Interval TSS VOUT=1V - 0.8 - ms
Note3. VOS offset is the voltage measurement defined as VOUT subtracted from VREFEN.
Note4. Regulation is measured at constant junction temperature by using a 1ms(on) / 9ms(off) current pulse. Devices are tested for load regulation
in the load range from 10mA to 2A for source and -10mA to -2A for sink capability.
PIN DESCRIPTIONS
PIN SYMBOL PIN DESCRIPTION
VIN Power Input Voltage.
GND Ground Pin
VOUT Output Voltage
VCNTL Gate Drive Voltage
REFEN Reference Voltage Input and Chip Enable
BLOCK DIAGRAM
3
ELECTRICAL SPECIFICATIONS (CONTINUED
)
ENABLE and Soft-Start
Protection
oC
VCNTL
ENABLE
FUNCTION
Soft-Start
Function
GATE
CONTROL
LOGIC
OCP
Function
UVP
Function
OTP
Function
REFEN
VIN
VOUT
GND
ERROR
AMPLIFIER
Advanced Power
Electronics Corp. AP1280AGN3
APPLICATION INFORMATIO
Input Capacitor and Layout Consideration
Consideration while designs the resistance of voltage divider
Thermal Consideration
4
Make sure the sinking current capability of pull-down NMOS if the lower resistance was
chosen so that the voltage on VREFEN is below 0.15V. In addition, the capacitor and voltage divide
r
form the lowpass filter. There are two reasons doing this design; one is for output voltage soft-start
while another is for noise immunity.
AP1280AGN3 regulators have internal thermal limiting circuitry designed to protect the device
during overload conditions.For continued operation, do not exceed maximum operation junction
temperature 125oC. The power dissipation definition in device is:
P D = (VIN - VOUT) x IOUT + VIN x IQ
The maximum power dissipation depends on the thermal resistance of IC package, PCB
layout, the rate of surroundings airflow and temperature difference between junction to ambient.
The maximum power dissipation can be calculated by following formula:
P D(MAX) = ( TJ(MAX) -TA ) / Rthja
Where TJ(MAX) is the maximum operation junction temperature 125oC, TAis the ambient
temperature and the Rthja is the junction to ambient thermal resistance. The junction to ambient
thermal resistance (Rthja is layout dependent) for DFN 3x3-8L is 150oC/W on standard JEDEC 51-7
(4 layers, 2S2P) thermal test board. The maximum power dissipation at TA=25
oC can be
calculated by following formula:
P D(MAX) = (125oC - 25oC) / 150oC/W = 0.66W
The thermal resistance Rthja of DFN 3x3-8L is determined by the package design and the PCB
design. However, the package design has been decided. If possible, it's useful to increase thermal
performance by the PCB design. The thermal resistance can be decreased by adding copper unde
r
the expose pad of DFN 3x3-8L package. We have to consider the copper couldn't stretch infinitely
and avoid the tin overflow.
Place the input bypass capacitor as close as possible to the AP1280AGN3. A low ESR
capacitor larger than 470uF is recommended for the input capacitor. Use short and wide traces to
minimize parasitic resistance and inductance.
Inappropriate layout may result in large parasitic inductance and cause undesired oscillation
between AP1280AGN3 and the preceding powe converter.
Advanced Power
Electronics Corp. AP1280AGN3
MARKING INFORMATION
DFN 3x3-8L
5
1280A
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