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PDF ML6554 Data sheet ( Hoja de datos )
| Número de pieza | ML6554 | |
| Descripción | 3A Bus Termination Regulator | |
| Fabricantes | Fairchild | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ML6554 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
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ML6554
3A Bus Termination Regulator
www.fairchildsemi.com
Features
• Can source and sink up to 3A, no heat sink required
• Integrated Power MOSFETs
• Generates termination voltages for DDR SDRAM,
SSTL-2 SDRAM, SGRAM, or equivalent memories
• Generates termination voltages for active termination
schemes for DDR SDRAM, GTL+, Rambus, VME,
LV-TTL, HSTL, PECL and other high speed logic
• VREF input available for external voltage divider
• Separate voltages for VCCQ and PVDD
• Buffered VREF output
• VOUT of ±3% or less at 3A
• Minimum external components
• Shutdown for standby or suspend mode operation
• 0° to +70°C and -40° to +85°C temperature ranges
available
• Thermal Shutdown ≈ 130ºC
Block Diagram
Description
The ML6554 switching regulator is designed to convert volt-
age supplies ranging from 2.3V to 4V into a desired output
voltage or termination voltage for various applications. The
ML6554 can be implemented to produce regulated output
voltages in two different modes. In the default mode, when
the VREF pin is open, the ML6554 output voltage is 50% of
the voltage applied to VCCQ. The ML6554 can also be used
to produce various user-defined voltages by forcing a voltage
on the VREFIN pin. In this case, the output voltage follows
the input VREFIN voltage. The switching regulator is capa-
ble of sourcing or sinking up to 3A of current while regulat-
ing an output VTT voltage to within 3% or less.
The ML6554, used in conjunction with series termination
resisitors, 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 other bus interface
standards such as DDR SDRAM, SSTL, CMOS, Rambus™,
GTL+, VME, LV-CMOS, LV-TTL, HSTL and PECL.
15 16
14
VCCQ AVCC VREFOUT
200kΩ
VREFIN
11
200kΩ
AGND
13
–
+
VREF BUFFER
OSCILLATOR/
RAMP
GENERATOR
ERROR AMP
+
–
VFB
10
1
VDD
9
VDD
12
SHDN
27
PVDD1 PVDD2
VL1
(VOUT)
3
SQ
–
R
+
RAMP
COMPARATOR
Q
6
VL2
(VOUT)
DGND
8
PGND1 PGND2
45
REV. 1.1.3 3/8/02
1 page  
PRODUCT SPECIFICATION
Applications
Using the ML6554 for SSTL Bus Termination
The circuit schematic in Figure 2 shows a recommended
approach for constructing a bus terminating solution for an
SSTL-2 bus. This circuit can be used in PC memory and
Graphics memory applications as shown in Figures 4 and 5.
Note that the ML6554 can provide the voltage reference
(VREF) and terminating voltages (VTT). Using the layout
as shown in Figures 6, 7, and 8, and measuring the VTT
performance using the test setup as described in Figure 9,
the ML6554 delivered a VTT ± 20mV for 1A to 3A loads
(see Figure 10). Table 1 provides a recommended parts list
for the circuit in Figure 2.
ML6554
Power Handling Capability of the PSOP
Package
Using the board layout shown in Figures 6, 7, and 8; solder-
ing the ML6554 to the board at zero LFPM the temperature
around the package measured 55ºC for 3A loads. Note that a
1 ounce copper plane was used in the board construction.
Airflow is not likely to be needed in the operation of this
device (assuming a board layout similar to that described
above). The power handling performance of the PSOP
package is shown by a study of the package manufacturer for
various airflow vs. θJA conditions in Figure 11.
Bus Termination Solutions for Others Buses
Table 3 provides a summary of various bus termination VREF
& VTT requirements. The ML6554 can be used for those
applications.
TPI
VTT
TO SDRAMS
GND
R1 100Ω
R2 100Ω
C9 0.1µF
C8 0.1µF
C1
820µF
F2V
OS-CON
L1 3.3µH C3 0.1µF
C2
0.1µF
C4 0.1µF
U1
ML6554
1
VDD
2
PVDD1
3
VL1
4
PGND1
5 PGND2
6
VL2
7
PVDD2
8
DGND
16
AVCC
15
VCCQ
14
VREFOUT
13
AGND
12
SHDN
11
VREFIN
10
VFB
9
VDD
R4 100kΩ
R5 1kΩ
C7 1nF
R3
100kΩ
2.5V TO 4V
C5 C6
330µF 330µF
VCCQ
VREFOUT
SHDN
VREFIN
GND
Figure 2.
REV. 1.1.3 3/8/02
5
5 Page 
PRODUCT SPECIFICATION
Vendor List
1. AVX
2. Sanyo
3. Tektronix
4. Coilcraft
5. Pulse
6. Gowanda
7. Xfmrs Inc.
8. Panasonic
9. Digikey
(207) 282-5111
(619) 661-6835
(408) 496-0800
(847) 639-6400
(800) 797-8573
(716) 532-2234
(317) 834-1066
(714) 373-7366
(800) 344-4539
60
60
ML6554
40 40
20
16Ld PSOP2
2.3x3.1mm PAD
1.9mm DIE
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
POWER (W)
NATURAL CONVECTION ΘJA TEST RESULTS
1.27mm PITCH PowerSOP™ 2
SLUG SOLDERED
20
16Ld PSOP2
2.3x3.1mm PAD
1.9mm DIE @ 0.8 WATTS
0
0 100 200 300 400 500
AIR VELOCITY (LFPM)
FORCED CONVECTION ΘJA TEST RESULTS
1.27mm PITCH PowerSOP™ 2
SLUG SOLDERED
Figure 11. Graphical Results Summary – 1S2P Test Board
REV. 1.1.3 3/8/02
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet ML6554.PDF ] | |
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