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P POWER SO ance High-Perform age ipation Pack Thermal Diss
FEATURING
November 1999 PRELIMINARY
ML6554
3A Bus Termination Regulator
GENERAL DESCRIPTION
The ML6554 switching regulator is designed to convert voltage 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 capable of sourcing or sinking up to 3A of current while regulating an output VTT voltage to within 3% or less. The ML6554, 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 other bus interface standards such as SSTL, CMOS, RambusTM, GTL+, VME, LV-CMOS, LV-TTL, and PECL.
FEATURES
s s s s
Power SOP package Can source and sink up to 3A, no heat sink required Integrated Power MOSFETs Generates termination voltages for SSTL-2 SDRAM, SGRAM, or equivalent memories Generates termination voltages for active termination schemes for GTL+, Rambus, VME, LV-TTL, 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 Thermal Shutdown 130C
s
s s s s s s s
BLOCK DIAGRAM
15 16 14 1 9 VDD 12 2 7
VCCQ
AVCC
VREFOUT OSCILLATOR/ RAMP GENERATOR
VDD
SHDN
PVDD1
PVDD2 VL1 (VOUT)
3
200k
+ - VREF BUFFER - + + ERROR AMP RAMP COMPARATOR S R Q Q VL2 (VOUT) 6
11
VREFIN 200k AGND -
13 VFB DGND PGND1 PGND2
10
8
4
5
1
ML6554
PIN CONFIGURATION
ML6554 16-Pin PSOP (U16)
VDD PVDD1 VL1 PGND1 PGND2 VL2 PVDD2 DGND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 AVCC VCCQ VREFOUT AGND SHDN VREFIN VFB VDD
TOP VIEW
PIN DESCRIPTION
PIN NAME FUNCTION PIN NAME FUNCTION
1 2 3 4 5 6 7 8
V DD PVDD1 VL1 P GND1 P GND2 VL2 PVDD2 D GND
Digital supply voltage Voltage supply for internal power transistors Output voltage/ inductor connection Ground for output power transistors Ground for output power transistors
9 10 11 12 13
V DD V FB VREFIN SHDN AGND VREFOUT VCCQ AVCC
Digital supply voltage Input for external compensation feedback Input for external reference voltage Shutdown active low. CMOS input level Ground for internal reference voltage divider Reference voltage output Voltage reference for internal voltage divider Analog voltage supply
Output voltage/inductor connection Voltage supply for internal power transistors Digital ground 16 14 15
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ML6554
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. PV DD .......................................................................................... 5.0V Voltage on Any Other Pin ...... GND - 0.3V to VIN + 0.3V Average Switch Current (IAVG) .................................. 3.0A Junction Temperature ....................................................... Storage Temperature Range ............................................. Lead Temperature (Soldering, 10 sec) .............................. Thermal Resistance (qJC)(Note 3) ........................... 2C/W Output Current, Source or Sink ................................. 3.0A
OPERATING CONDITIONS
Temperature Range ....................................... 0C to 70C PVDD Operating Range ................................ 2.0V to 4.0V
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, PVDD = 3.3V10%, TA = Operating Temperature Range (Note 1)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS SWITCHING REGULATOR V TT Output Voltage, SSTL_2 (See Figure 1) IOUT = 0, VREF = open Note 2 IOUT = 3A, VREF = open Note 2 VREFOUT Internal Resistor Divider IOUT = 0 Note 2 VCCQ = 2.3V VCCQ = 2.5V VCCQ = 2.7V VCCQ = 2.3V VCCQ = 2.5V VCCQ = 2.7V VCCQ = 2.3V VCCQ = 2.5V VCCQ = 2.7V ZIN VREF Reference Pin Input Impedance Switching Frequency DVOFFSET Offset Voltage VTT - VREFOUT SUPPLY IQ Quiescent Current IOUT = 0, no load IVCCQ I AVCC I DVCC BUFFER IREF Output Load Current 3 mA 10 500 7 A A mA VCCA = 2.5V No Load VCCQ = 2.5 -12.5 Note 2 VCCQ = 0 1.12 1.22 1.32 1.09 1.19 1.28 1.139 1.238 1.337 1.15 1.25 1.35 1.15 1.25 1.35 1.15 1.25 1.35 100 650 12.5 1.18 1.28 1.38 1.21 1.31 1.42 1.162 1.263 1.364 V V V V V V V V V kW kHz mV
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions. Note 2: AVCC, PVDD = 3.3V 10% Note 3: Infinite heat sink
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ML6554
FUNCTIONAL DESCRIPTION
This switching regulator is capable of sinking and sourcing 3A of current without an external heatsink. The ML6554 uses a power surface mount package (PSOP) that includes an integrated heat slug. The heat can be piped through the bottom of the device and onto the PCB (Figure 2). The ML6554 integrates two power MOSFETs that can be used to source and sink 3A of current while maintaining a tight voltage regulation. Using the external feedback, the output can be regulated well within 3% or less, depending on the external components chosen. Separate voltage supply inputs have been added to accommodate applications with various power supplies for the databus and power buses. OUTPUTS The output voltage pins (VL1, VL2) are tied to the databus, address, or clock lines via an external inductor. See the Applications section for recommendations. Output voltage is determined by the VCCQ or VREFIN inputs. INPUTS The input voltage pins (VCCQ or VREFIN) determine the output voltages (VL1 or VL2) . In the default mode, where the VREFIN pin is floating, the output voltage is 50% of the VCCQ input. VCCQ can be the reference voltage for the databus. Output voltage can also be selected by forcing a voltage at the VREFIN pin. In this case, the output voltage follows the voltage at the VREFIN input. Simple voltage dividers can be used this case to produce a wide variety of output voltages between 2.3V to 4V. VREF INPUT AND OUTPUT The VREFIN input can be used to force a voltage at the outputs (Inputs section, above). The VREFOUT pin is an output pin that is driven by a small output buffer to provide the VREF signal to other devices in the system. The output buffer is capable of driving several output loads. The output buffer can handle 3mA. OTHER SUPPLY VOLTAGES Several inputs are provide for the supply voltages: PVDD1, PVDD2, AVCC, and VDD. The PVDD1 and PVDD2 and provide the power supply to the power MOSFETs. VDD provides the voltage supply to the digital sections, while AVCC supplies the voltage for the analog sections. Again, see the Applications section for recommendations. FEEDBACK INPUT The VFB pin is an input that can be used for closed loop compensation. This input is derived from the voltage output. See application section for recommendation.
2.5V TO 4V R2 100 R1 100 C9 0.1F C8 0.1F
R3 100k
220F
220F
U1 ML6554
TPI 1 2 VTT C1 820F F2V OS-CON TO SDRAMS L1 3.3H C3 0.1F 3 4 C2 0.1F C4 0.1F 5 6 7 8 VDD PVDD1 VL1 PGND1 PGND2 VL2 PVDD2 DGND AVCC VCCQ VREFOUT AGND SHDN VREFIN VFB VDD 16 15 14 13 12 11 10 9 SHDN VREFIN VCCQ VREFOUT
R4 100k C7 1nF GND
R5 1k GND
Figure 1.
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ML6554
APPLICATIONS
USING THE ML6554 FOR SSTL BUS TERMINATION The circuit schematic in Figure 1 shows a recommended approach for an 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 3 and 4. Note that the ML6554 can provide the voltage reference (VREF) and terminating voltages (VTT). Using the layout as shown in Figures 5, 6, and 7, and measuring the VTT performance using the test setup as described in Figure 8, the ML6554 delivered a VTT 20mV for 1A to 3A loads (see Figure 9). Table 1 provides a recommended parts list. For more recent Applications Notes or Evaluation Boards contact Micro Linear. POWER HANDLING CAPABILITY OF THE PSOP PACKAGE Using the board layout shown in Figures 5,6, and 7; soldering the ML6554 to the board at zero LFPM the temperature around the package measured 55 for 3A C loads. Note that a 1ounce 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. qJA conditions in Figure 10. BUS TERMINATION SOLUTIONS FOR OTHER BUSES Table 2 provides a summary of various bus termination VREF & VTT requirements. The ML6554 can be used for those applications.
HEAT SLUG
Figure 2. Cutaway view of PSOP Package
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5
ML6554
168/184/208-PIN DIMM CONNECTORS AND SDRAM/SGRAM MODULES TERMINATION RESISTORS
PC CHIP SET NORTHBRIDGE
DATA LINE, CLOCK LINES, ADDRESS LINES, CONTROL LINES
TERMINATION RESISTORS
VTT
ML6554 VREF
Figure 3. Complete Termination Solution PC Main Memory (PC Motherboard)
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ML6554
SO DIMM AND MODULES
TERMINATION RESISTORS SGRAM
3D GRAPHIC CHIP
DATA LINE, CLOCK LINES, ADDRESS LINES, CONTROL LINES
TERMINATION RESISTORS 2.5V
VREF ML6554 VTT
VOLTAGE REGULATOR 5V OR 3.3V
AGP/PCI BUS
Figure 4. Complete Termination Solution Graphics Memory Bus - AGP Graphics Cards
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ML6554
Figure 5. Top Silk
Figure 6. Top Layer
Figure 7. Bottom Layer
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ML6554
3.3V POWER SUPPLY
V
A
ACTIVE CLAMP
VDD VCCQ VCCQ SUPPLY ML6554 EVAL GND VTT CURRENT SOURCE/SINK POWER SUPPLY ITT
V
A
Figure 8. Test Circuit Setup
VTT VARIANCE WITH VDD@ITT (VCCQ 2.5V) TESTED WITH EVAL PCB 1.29 ITT 3A SINKING
2A SINKING 1.28 1A SINKING
VTT (V)
0A SINKING 1.27 3A SOURCING
2A SOURCING 1.26 2.0
2.5
3.0 VDD (V)
3.5
4.0
1A SOURCING
Figure 9. VTT Performance for SSTL-2 Bus
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ML6554
ITEM RESISTORS 1 2 3 CAPACITORS 4 5 6 7 8 ICS 9 MAGNETICS 10 1 3.3H 5A inductor SMD Coilcraft/D03316P-332HC Pulse Eng./ P0751.332T Gowanda/SMP3316-331M XFMRS inc./XF0046-S4 Tektronics/131-4353-00 Sullins/PTC36SAAN (36 PINS) L1 2 1 2 3 1 2 1 2 1 100W1210 SMD 1kW 1210 SMD 100kW1210 SMD 0.1F 1210 Film SMD 820F 2V Solid Elect. SMD 330F Tant 6.3V 100mW 1nF 1210 Film SMD 0.1F 0805 Film ML6554 Bus Terminator Power SOP Package Panasonic/ERJ-8ENF1000V Panasonic/ERJ-8ENF1001V Panasonic/ERJ-8ENF1003V Panasonic/ECV3VB1E104K Panasonic/ECU-V1H104KBW Sanyo/ 2SV820M Os Con AVX/ TPSE337M006R0100 Panasonic/ECU-V1H102KBM Panasonic/ECJ-2VF1C104Z ML6554CU R1, R2 R5 R3, R4 C2, C8, C9 C1 C5, C6 C7 C3, C4 U1 QTY DESCRIPTION MANUFACTURER / PART NUMBER DESIGNATOR
OTHER 11 12 1 1 Scope probe socket 12 Pin breakaway strip TP1 I/O, standoffs
Table 1. Recommend Parts List for SSTL-2 Termination Circuit
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
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ML6554
60 60
40 JA (C/W) 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 JA TEST RESULTS 1.27mm PITCH PowerSOPTM 2 SLUG SOLDERED JA (C/W)
40
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 JA TEST RESULTS 1.27mm PITCH PowerSOPTM 2 SLUG SOLDERED
Figure 10. Graphical Results Summary - 1S2P Test Board
DRAWING NUMBER Applicable Jedec Spec Substrate Material Dimensions (LxW) (Overall) Dimensions (LxW) (Metallization) Dimensions (LxW) (Inner Planes) Thickness Pitch Stackup (# Signal Layers, # Cu Planes) Cu Trace Coverage (Signal Layer) Cu Coverage (Internal Layer) Trace Width (Spec/Measured) Trace Cu Thickness (Spec/Measured) Inner Cu Thickness (Spec/Measured) Build #
ENG-CB-1007 REV A JC 51-X (Note 1) (Sroposed Spec) FR-4 114.3 x 76.2mm 55 x 65mm 73 x 73mm 1.6 mm 1.27mm 1S2P 12% 100% 235.525.5/288m 7014/67m 353.5/31m C1797
Note 1: Proposed Spec "Thermal Test Board with Two Internal Solid Copper Planes for leaded Surface Mount Packages".
Figure 11. Test Board Layout for QJA vs. Airflow
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ML6554
BUS
DESCRIPTION
DRIVING METHOD Open Drain
VDDQ
VTT
VREF
MICRO LINEAR SOUTIONS ML6554CU; Mode: VREF Input = 1.5V, VCC = 5V
INDUSTRY SYSTEM COMPONENTS 300 to 500MHz Processor; PC Chipsets; GTLP 16xxx Buffers; Fairchild, Texas Instr. SSTL SDRAM; Hitachi, Fujitsu, NEC, Micro, Mitsubishi nDRAM, RAMBUS, Intel, Toshiba Processors or backplanes; LV-TTL SDRAM, EDO RAM
GTL+
Gunning Transceiver Bus Plus
5v or 3.3V 1.5V10% Note 10 Note12
1.0V2% Note 11
SSTL_2
Series Stub Terminated Logic for 2V
Symmetric Drive, Series Resistance
2.5V10% 0.5x(VDDQ) 3%
2.5V
RAMBUS
RAMBUS Signaling Logic Low Voltage TTL Logic or PECL or 3.3V VME
Open Drain
None Specified
2.5V
2.0V
LV-TTL
Symmetric Drive
3.310%
VDDQ/2
3.3V
ML6554CU or ML6553CS; Mode: VREF Input = Floating or Forced, VCC = 3.3V ML6553CS; Mode: VREF Input = Open, VCC = VDDQ ML6553CS; Mode: VREF Input = Open, VCC = VDDQ
Table 2. Termination Solutions Summary By Buss Type
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ML6554
PHYSICAL DIMENSIONS
inches (millimeters)
Package: U16 16-Pin PSOP
0.386 - 0.393 9.80 - 9.98 16 HEAT SLUG DIMENSIONS: 0.079 x 0.279 (2.01 x 7.09) 0.150 - 0.157 0.230 - 0.244 3.81 - 3.99 (5.84 - 6.20)
PIN 1 ID HEAT SLUG
1 0.017 - 0.027 0.43 - 0.69 (4 PLACES) 0.050 BSC (1.27 BSC) 0.061 - 0.068 (1.55 - 1.73) 0 - 8
0.055 - 0.061 (1.40 - 1.55)
0.014 - 0.019 (0.35 - 0.49)
SEATING PLANE
0.00 - 0.004 (0.127 - 0.25)
0.016 - 0.035 (0.41 - 0.89)
0.0075 - 0.0098 (0.19 - 0.25)
ORDERING INFORMATION
PART NUMBER ML6554CU TEMPERATURE RANGE 0C to 70C PACKAGE 16-Pin PSOP (U16)
Micro Linear Corporation 2092 Concourse Drive San Jose, CA 95131 Tel: (408) 433-5200 Fax: (408) 432-0295 www.microlinear.com (c) Micro Linear 1999. property of their respective owners. is a registered trademark of Micro Linear Corporation. All other trademarks are the
Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; 5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174; 5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223; 5,838,723; 5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending. Micro Linear makes no representations or warranties with respect to the accuracy, utility, or completeness of the contents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. No license, express or implied, by estoppel or otherwise, to any patents or other intellectual property rights is granted by this document. The circuits contained in this document are offered as possible applications only. Particular uses or applications may invalidate some of the specifications and/or product descriptions contained herein. The customer is urged to perform its own engineering review before deciding on a particular application. Micro Linear assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Micro Linear products including liability or warranties relating to merchantability, fitness for a particular purpose, or infringement of any intellectual property right. Micro Linear products are not designed for use in medical, life saving, or life sustaining applications.
DS6554-01
NOVEMBER, 1999
13
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