FAN6555 2A DDR Bus Termination Regulator

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1 A DDR Bus Termination Regulator Features Can source and sink up to A continous, 3A peak No heatsink required Integrated Power MOSFETs Generates termination voltages for DDR SDRAM V REF input available for external voltage divider Separate voltages for and P Buffered V REF output V OUT of ±3% or less at A Minimum external components 16-pin SOIC package -40 C to +85 C operating temperature range Shutdown for standby or suspend mode operation Thermal Shutdown 130ºC Description The switching regulator is designed to convert voltage supplies ranging from.3v to 4V into a desired output voltage or termination voltage for DDR SDRAM memory. The can be implemented to produce regulated output voltages in two different modes. In the default mode, when the V REF pin is open, the output voltage is 50% of the voltage applied to. The can also be used to produce various user-defined voltages by forcing a voltage on the pin. In this case, the output voltage follows the input voltage. The switching regulator is capable of sourcing or sinking up to A of current while regulating an output V TT voltage to within 3% or less. Transient output currents of ±3A can also be accommodated. The can also be used in conjunction with series termination resisitors to provide 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. Block Diagram AV CC P1 7 P OSCILLATOR/ RAMP GENERATOR V L1 (V OUT ) 3 00kΩ 11 00kΩ A 13 + V REF BUFFER + ERROR AMP + S R RAMP COMPARATOR Q Q V L (V OUT ) 6 V FB 10 8 D P P REV /4/03

2 PRODUCT SPECIFICATION Pin Configuration 16-Pin SOIC (M16) 1 16 AV CC P1 15 V L P A P 5 1 V L 6 11 P 7 10 V FB D 8 9 TOP VIEW Pin Description Pin Name Function 1 Digital supply voltage P1 Voltage supply for internal power transistors 3 V L1 Output voltage/ inductor connection 4 P 1 Ground for output power transistors 5 P Ground for output power transistors 6 V L Output voltage/inductor connection 7 P Voltage supply for internal power transistors 8 D Digital ground 9 Digital supply voltage 10 V FB Input for external compensation feedback 11 Input for external reference voltage 1 Shutdown active low. CMOS input level 13 A Ground for internal reference voltage divider 14 Reference voltage output 15 Voltage reference for internal voltage divider 16 AV CC Analog voltage supply REV /4/03

3 PRODUCT SPECIFICATION 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. Parameter Min. Max. Units P 4.5 V Voltage on Any Other Pin 0.3 V IN V Average Switch Current (I AVG ).0 A Junction Temperature 150 C Storage Temperature Range C Lead Temperature (Soldering, 10 sec) 300 C Thermal Resistance: Junction to Case (θ JC ) 30 C/W Junction to Ambient (θ JA ) 88 Output Current, Source or Sink (peak) 3.0 A Operating Conditions Parameter Min. Max. Units Temperature Range C P Operating Range V Operating Range V Electrical Characteristics Unless otherwise specified, AV CC = = P = 3.3V ±10%, T A = Operating Temperature Range (Note 1) Symbol Parameter Conditions Min. Typ. Max. Units Switching Regulator V TT Output Voltage, V TT (See Figure 1) I OUT = 0, V REF = open Note I OUT = ±A, V REF = open T A = 5 C Note Internal Resistor Divider I OUT = 0 Note Notes 1. Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.. AV CC, P = 3.3V ±10% =.3V V =.5V V =.7V V =.3V V =.5V V =.7V V =.3V V =.5V V =.7V V Z IN V REF Reference Pin Input Note = kω Impedance Switching Frequency 650 khz V OFFSET Offset Voltage V TT AV CC =.5V No Load = mv Supply I Q Quiescent Current I OUT = 0, no load =.5V I VCCQ 6 10 µa I AVCC ma I AVCC SD ma I VDD ma I VDD SD ma I PVDD µa Buffer I REF Output Current Capability 3 ma REV /4/03 3

4 PRODUCT SPECIFICATION Functional Description The integrates two power MOSFETs that can be used to source and sink A 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 (V L1, V L ) 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 or inputs. Inputs The input voltage pins ( or ) determine the output voltages (V L1 or V L ). In the default mode, where the pin is floating, the output voltage is 50% of the input. can be the reference voltage for the databus. Output voltage can also be selected by forcing a voltage at the pin. In this case, the output voltage follows the voltage at the input. Simple voltage dividers can be used in this case to produce a wide variety of output voltages between 0.7V and 0.7V. VREF Input and Output The input can be used to force a voltage at the outputs (Inputs section, above). The pin is an output pin that is driven by a small output buffer to provide the V REF 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: P1, P, AV CC, and. The P1 and P provide the power supply to the power MOSFETs. provides the voltage supply to the digital sections, while AV CC supplies the voltage for the analog sections. Again, see the Applications section for recommendations. Feedback Input The V FB 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. R 100Ω C8 0.1µF.5V TO 4V R1 100Ω C9 0.1µF U1 R3 100kΩ C5 470µF V TT TPI TO SDRAMS C1 80µF FV OS-CON L1 3.3µH C3 0.1µF C 0.1µF C4 0.1µF P1 V L1 P 1 P V L P D AV CC A V FB R4 100kΩ R5 1kΩ C7 1nF Figure 1. 4 REV /4/03

5 PRODUCT SPECIFICATION Applications Using the for DDR Bus Termination The circuit schematic in Figure 1 shows a recommended approach for constructing a bus terminating solution for a DDR bus. This circuit can be used in PC memory and Graphics memory applications as shown in Figures 3 and 4. Note that the can provide the voltage reference (V REF ) and terminating voltages (V TT ). Using the layout as shown in Figures 5, 6, and 7, and measuring the V TT performance using the test setup as described in Figure 8, the delivered a V TT ± 0mV for 1A to A loads (see Figure 9). Table 1 provides a recommended parts list. An alternate application circuit for the is shown in Figure. The number of external components is reduced compared to the circuit in Figure 1. This is achieved by replacing four, 0.1µF bypass capacitors with one, low ESR, 10µF ceramic capacitor placed right next to U1. Two 100Ω resistors are also eliminated. High value, surface-mount MLC capacitors were not available when the original application circuit (Figure 1) was developed. Both application circuits offer the same electrical performance but the circuit shown in Figure has a reduced bill-of-materials. Table shows the recommended parts list for the circuit of Figure. Bus Termination Solutions for Others Buses Table 3 provides a summary of various bus termination V REF & V TT requirements. The can be used for those applications..5v TO 4V U1 R3 100kΩ C5 470µF V TT TO SDRAMS C1 80µF FV OS-CON L1 3.3µH C 0.1µF C3 10µF P1 V L1 P 1 P V L P D AV CC A V FB R1 100kΩ R 1kΩ C4 1nF Figure. Alternate Application Circuit REV /4/03 5

6 PRODUCT SPECIFICATION 168/184/08-PIN DIMM CONNECTORS AND SDRAM/SGRAM MODULES TERMINATION RESISTORS PC CHIP SET NORTHBRIDGE DATA LINE, CLOCK LINES, ADDRESS LINES, CONTROL LINES TERMINATION RESISTORS VTT VREF Figure 3. Complete Termination Solution PC Main Memory (PC Motherboard) SO DIMM AND MODULES TERMINATION RESISTORS SGRAM 3D GRAPHIC CHIP DATA LINE, CLOCK LINES, ADDRESS LINES, CONTROL LINES VOLTAGE REGULATOR TERMINATION RESISTORS.5V VTT VREF 5V OR 3.3V AGP/PCI BUS Figure 4. Complete Termination Solution Graphics Memory Bus AGP Graphics Cards 6 REV /4/03

1µF U1 R3 100kΩ C5 470µF V TT TPI TO SDRAMS C1 80µF FV OS-CON L1 3.3µH C3 0.

7 PRODUCT SPECIFICATION Figure 5. Top Silk Figure 6. Top Layer Figure 7. Bottom Layer R 100Ω C8 0.1µF.5V TO 4V R1 100Ω C9 0.1µF U1 R3 100kΩ C5 470µF V TT TPI TO SDRAMS C1 80µF FV OS-CON L1 3.3µH C3 0.1µF C 0.1µF C4 0.1µF P1 V L1 P 1 P V L P D AV CC A V FB R4 100kΩ R5 1kΩ C7 1nF REV /4/03 7

8 PRODUCT SPECIFICATION 3.3V POWER SUPPLY V A ACTIVE CLAMP SUPPLY EVAL V TT I TT CURRENT SOURCE/SINK POWER SUPPLY V A Figure 8. Test Circuit Setup V TT VARIANCE TT (.5V) TESTED WITH EVAL PCB 1.9 I TT A SINKING 1A SINKING V TT (V) A SINKING A SOURCING 1A SOURCING (V) Figure 9. VTT Performance for DDR Bus 8 REV /4/03

9 PRODUCT SPECIFICATION Table 1. Recommend Parts List for Figure 1. Item Qty Description Manufacturer / Part Number Designator Resistors 1 100Ω110 SMD Panasonic/ERJ-8ENF1000V R1, R 1 1kΩ 110 SMD Panasonic/ERJ-8ENF1001V R kΩ110 SMD Panasonic/ERJ-8ENF1003V R3, R4 Capacitors µF 110 Film SMD Panasonic/ECV3VB1E104K C, C8, C9 Panasonic/ECU-V1H104KBW µF V Solid Elect. SMD Sanyo/SV80M Os Con C µF 6.3V Solid Elect. SMD Sanyo/6SVP470M Os Con C nF 110 Film SMD Panasonic/ECU-V1H10KBM C µF 0805 Film Panasonic/ECJ-VF1C104Z C3, C4 ICs 9 1 Bus Terminator M U1 Magnetics µH 5A inductor SMD Coilcraft/D03316P-33HC Pulse Eng./ P T Gowanda/SMP M XFMRS inc./xf0046-s4 L1 Other 11 1 Scope probe socket Tektronics/ TP Pin breakaway strip Sullins/PTC36SAAN (36 PINS) I/O, standoffs Table. Recommend Parts List for Figure. Item Qty Description Manufacturer / Part Number Designator Resistors 1 100kΩ 0805 SMD Panasonic/ERJ-8ENF1000V R1, R3 1 1kΩ 0805 SMD Panasonic/ERJ-8ENF1000V R Capacitors µF, 110 Film SMD Panasonic/ECV3VB1E104K C Panasonic/ECU-V1H104KBW µF V Solid Elect. SMD Sanyo/SV80M Os Con C µF 6.3V Solid Elect. SMD Sanyo/6SVP470M Os Con C nF 110 Film SMD Panasonic/ECU-V1H10KBM C µF 6.3V Ceramic TDK/C01X5R0J106M C3 ICS 8 1 Bus Terminator M U1 Magnetics µH 5A inductor SMD Coilcraft/D03316P-33HC Pulse Eng./ P T Gowanda/SMP M XFMRS inc./xf0046-s4 L1 Other 10 1 Scope probe socket Tektronics/ TP Pin breakaway strip Sullins/PTC36SAAN (36 PINS) I/O, standoffs REV /4/03 9

10 PRODUCT SPECIFICATION Vendor List 1. AVX (07) Sanyo (619) Tektronix (408) Coilcraft (847) Pulse (800) Gowanda (716) Xfmrs Inc. (317) Panasonic (714) Digikey (800) Table 3. Termination Solutions Summary By Bus Type Bus GTL+ DDR (SSTL-) RAMBUS LV-TTL Description Gunning Transceiver Bus Plus Series Stub Terminated Logic for V RAMBUS Signaling Logic Low Voltage TTL Logic or PECL or 3.3V VME Driving Fairchild Method VDDQ VTT V REF Solutions Open Drain 3.3V 1.5V±10% 1.0V±% ; Mode: V REF Input = 1.5V, V CC = 3.3V Symmetric Drive, Series Resistance Open Drain Symmetric Drive.5V±10% 0.5x (Q ) ±3% None Specified.5V, ML6554CU, or ML6553CS; Mode: V REF Input = Floating or Forced, V CC = 3.3V.5V.0V ML6553CS; Mode: V REF Input = Open, V CC = Q 3.3±10% Q / 3.3V ML6553CS; Mode: V REF Input = Open, VCC = VDDQ Industry System Components 300 to 500MHz Processor; PC Chipsets; GTLP 16xxx Buffers; Fairchild, Texas Instr. DDR SDRAM; Hitachi, Fujitsu, NEC, Micro, Mitsubishi ndram, RAMBUS, Intel, Toshiba Processors or backplanes; LV-TTL SDRAM, EDO RAM 10 REV /4/03

11 PRODUCT SPECIFICATION Mechanical Dimensions Inches (Millimeters) Package: M16 16-Pin SOIC Symbol Inches Millimeters Min. Max. Min. Max. A A B C D E e.050 BSC 1.7 BSC H h L N α ccc Notes Notes: 1. Dimensioning and tolerancing per ANSI Y14.5M "D" and "E" do not include mold flash. Mold flash or protrusions shall not exceed.010 inch (0.5mm). 3. "L" is the length of terminal for soldering to a substrate. 4. Terminal numbers are shown for reference only. 5. "C" dimension does not include solder finish thickness. 6. Symbol "N" is the maximum number of terminals E H 1 8 A D A1 α SEATING C e B PLANE LEAD COPLANARITY L ccc C h x 45 C REV /4/03 11

12 PRODUCT SPECIFICATION Ordering Information Part Number Temperature Range Package M -40 C to +85 C 16-Pin SOIC (M16) MX -40 C to +85 C 16-Pin SOIC in tape-and-reel DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, or (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in significant injury of the user.. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. 8/4/03 0.0m 00 Stock#DS Fairchild Semiconductor Corporation

ML6554 3A Bus Termination Regulator

ML6554 3A Bus Termination Regulator 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