G2995 Global Mixed-mode Technology Inc. DDR Termination Regulator Features General Description The G2995 is a linear regulator designed to meet the JEDEC SSTL-2 and SSTL-3 (Series Stub Termination Logic) specifications for termination of DDR-SDRAM. It contains a high-speed operational amplifier that provides excellent response to the load transients. This device can deliver 1.5A continuous current and transient peaks up to 3A in the application as required for DDR-SDRAM termination. With an independent VSENSE pin, the G2995 can provide superior load regulation. The G2995 provides a VREF output as the reference for the applications of the chipset and DIMMs. Operation Supply Voltage: 1.6V to 5.5V Low Supply Current: 280µA @ 2.5V Low Output Offset Source and Sink Current Low External Component Count No Inductor Required No external Resistors Required Thermal Shutdown Protection SOP-8L with Power-Pad package Applications DDR-SDRAM Termination Voltage DDR-I / DDR-II Termination Voltage SSTL-2 SSTL-3 The G2995 can easily provide the accurate VTT and VREF voltages without external resistors that PCB areas can be reduced. The quiescent current is as low as 280µA @ 2.5V. So the power consumption can meet the low power consumption applications. Ordering Information ORDER NUMBER ORDER NUMBER (Pb free) MARKING TEMP. RANGE PACKAGE G2995P1U G2995F1U G2995P1Uf G2995F1Uf G2995 G2995 -40°C to 85°C -40°C to 85°C SOP-8 SOP-8 (FD) Note: P1:SOP-8 U: Tape & Reel F1:SOP-8(FD) (FD): Thermal Pad Pin Configuration Typical Application Circuit G2995 NC 8 1 GND 2 7 VSENSE 3 6 VREF 4 5 VTT PVIN VDDQ VDDQ=2.5V Thermal Pad VDD=2.5V AVIN AVIN VREF 47µF VDDQ VREF=1.25V 0.01µF VSENSE PVIN + + VTT GND VTT=1.25V + 220µF SOP-8 TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 1 G2995 Global Mixed-mode Technology Inc. Absolute Maximum Ratings Recommend Operation Range (1) Supply Voltage PVIN, AVIN, VDDQ to GND……………-0.3V to +6V Operating Ambient Temperature Range TA…….…………………………….……...-40°C to +125°C Maximum Junction Temperature, TJ…..……….….150°C Storage Temperature Range, TSTG….….-65°C to+150°C Reflow Temperature (Soldering, 10 sec)…………260°C Electrostatic Discharge, VESD Human body mode..………………………………2000V(2) SOP-8L Thermal Resistance (θJA)…….………130°C/W SOP-8L (FD) Thermal Resistance (θJA)……...50°C/W(3) SOP-8L (FD) Thermal Resistance (θJA)………41°C/W(4) SOP-8L (FD) Thermal Resistance (θJc)……….12°C/W Operating Ambient Temperature Range TA…….…………………………….……….-40°C to +85°C AVIN to GND………………………..………1.6V to +5.5V PVIN, VDDQ to GND.………………………1.6V to AVIN Note: (1) :Absolute maximum rating indicates limits beyond which damage to the device may occurs. (2) : Human body model : C = 100pF, R = 1500Ω, 3 positive pulses plus 3 negative pulses (3) : The package is placed on a 2-layer PCB (2oz/2oz) with 6 vias. (4) : The package is placed on a 2-layer PCB (2oz/2oz) with 6 vias. The airflow is used. Electrical Characteristics Specifications with standard typeface are for TA=25°C. Unless otherwise specified, AVIN=PVIN=2.5V, VDDQ=2.5V PARAMETER SYMBOL VREF Voltage VREF VREF Output impendence ZREF VTT Output voltage VTT Output Voltage Offset (VREF- VTT) Quiescent Current VDDQ input Impedence VSENSE input current Thermal Shutdown Thermal Shutdown Hystersis VTT VosVtt IQ CONDITION VDDQ=2.3V VDDQ=2.5V VDDQ=2.7V IREF =-30µA to + 30µA IOUT=0A VDDQ=2.3V VDDQ=2.5V VDDQ=2.7V IOUT=±1.5A VDDQ=2.3V VDDQ=2.5V VDDQ=2.7V IOUT=0A IOUT=-1.5A IOUT=+1.5A IOUT=0A ZVDDQ ISENSE TSD THsy MIN TYP MAX UNIT 1.11 1.21 1.31 --- 1.145 1.245 1.345 1.15 1.19 1.29 1.39 --- V V V kΩ 1.11 1.21 1.31 1.152 1.252 1.352 1.19 1.29 1.39 V V V 1.11 1.21 1.31 -40 -40 -40 ----------- 1.152 1.252 1.352 0 0 0 280 100 20 150 25 1.19 1.29 1.39 40 40 40 500 --------- V V V mV mV mV µA KΩ nA °C °C TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 2 G2995 Global Mixed-mode Technology Inc. Typical Performance Characteristics AVIN=2.5V, PVIN=2.5V, VDDQ=2.5V, CAVIN=0.1µF, CPVIN=47µF, CVREF=0.01µF, CVTT=220µF, TA=25°C, unless otherwise noted. VREF vs IREF 1.3 250 1.28 230 1.26 VREF(V) IQ(µA) IQ vs AVIN 270 210 1.24 190 1.22 170 1.2 150 1.18 2 2.5 3 3.5 4 4.5 5 5.5 -30 -20 -10 0 10 20 30 IREF(µA) AVIN(V) VTT vs IOUT Temperature VREF vs VDDQ 3 1.252 2.5 1.248 VTT(V) VREF(V) 2 1.5 1.244 1.24 0°C 1 25°C 1.236 0.5 85°C 1.232 -100 0 2 2.5 3 3.5 4 4.5 5 5.5 VDDQ(V) -75 -50 -25 0 25 50 75 100 IOUT(mA) TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 3 G2995 Global Mixed-mode Technology Inc. Typical Performance Characteristics AVIN=2.5V, PVIN=2.5V, VDDQ=2.5V, CAVIN=0.1µF, CPVIN=47µF, CVREF=0.01µF, CVTT=220µF, TA=25°C, unless otherwise noted. IQ vs AVIN Temperature VTT vs VDDQ 3 270 2.5 250 2 230 25°C IQ(µA) VTT(V) 85°C 1.5 1 190 0.5 170 0 0°C 210 150 2 2.5 3 3.5 4 4.5 5 5.5 2 2.5 3 VDDQ(V) 4 4.5 5 5.5 AVIN(V) Maximum Sourcing Current vs AVIN (VDDQ=2.5V, PVIN=1.8V) Maximum Sourcing Current vs AVIN (VDDQ=2.5V, PVIN=2.5V) 1.4 1.8 1.2 1.7 OUTPUT CURRENT(A) OUTPUT CURRENT(A) 3.5 1 0.8 0.6 0.4 0.2 1.6 1.5 1.4 1.3 1.2 0 1.1 2 2.5 3 3.5 4 4.5 5 5.5 2 AVIN(V) 2.5 3 3.5 4 4.5 5 5.5 AVIN(V) Maximum Sourcing Current vs AVIN (VDDQ=2.5V, PVIN=3.3V) OUTPUT CURRENT(A) 3 2.8 2.6 2.4 2.2 2 2 2.5 3 3.5 4 4.5 5 5.5 AVIN(V) TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 4 G2995 Global Mixed-mode Technology Inc. Typical Performance Characteristics AVIN=2.5V, PVIN=2.5V, VDDQ=2.5V, CAVIN=0.1µF, CPVIN=47µF, CVREF=0.01µF, CVTT=220µF, TA=25°C, unless otherwise noted. Maximum Sourcing Current vs AVIN (VDDQ=1.8V, PVIN=1.8V) 3 1.4 2.8 1.2 OUTPUT CURRENT(A) OUTPUT CURRENT(A) Maximum Sinking Current vs AVIN (VDDQ=2.5V) 2.6 2.4 2.2 2 1.8 1 0.8 0.6 0.4 0.2 1.6 0 1.4 2 2.5 3 3.5 4 4.5 5 2 5.5 2.5 3 3.5 4 4.5 5 5.5 AVIN(V) AVIN(V) Maximum Sourcing Current vs AVIN (VDDQ=1.8V, PVIN=3.3V) Maximum Sinking Current vs AVIN (VDDQ=1.8V) 2.8 IO=200m 3 2.4 OUTPUT CURRENT(A) OUTPUT CURRENT(A) 2.6 2.2 2 1.8 1.6 1.4 2.8 2.6 2.4 2.2 1.2 2 1 2 2.5 3 3.5 4 4.5 5 2 5.5 AVIN(V) 2.5 3 3.5 4 4.5 5 5.5 AVIN(V) VOSVTT vs Temperature(VDDQ=2.5V) 30 Sourcing 1.5A VOSVTT(mV) 20 10 No Load 0 -10 Sinking 1.5A -20 -30 0 25 50 75 100 125 Temperature(℃) TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 5 Global Mixed-mode Technology Inc. G2995 Typical Performance Characteristics (continued) AVIN=2.5V, PVIN=2.5V, VDDQ=2.5V, CAVIN=0.1µF/Ceramic X7R/0603/6.3V/TDK, CPVIN=68µF/6.3V POSCAP Series/SANYO, CVTT=330µF*2/6.3V POSCAP Series/SANYO, TA=25°C, unless otherwise noted. ILoad=0.5A Transient (Sinking) ILoad=0.5A Transient (Sourcing) ILoad=1A Transient (Sinking) ILoad=1A Transient (Sourcing) ILoad=1.5A Transient (Sinking) ILoad=1.5A Transient (Sourcing) TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 6 G2995 Global Mixed-mode Technology Inc. Pin Description NUMBER NAME 1 2 NC GND FUNCTION 3 4 VSENSE VREF Feedback pin for regulating VTT Buffered output that is a reference output of VDDQ/2 5 6 VDDQ AVIN Input for internal reference which equals to VDDQ/2 Analog input pin 7 8 PVIN VTT Power input pin Output voltage for connection to termination resistors, equal to VDDQ/2 Ground Block Diagram VDDQ AVIN PVIN 50k VREF + + - - 50k VTT VSENSE GND Description VTT VDD The G2995 is a linear bus termination regulator designed to meet the JEDEC SSTL-2 and SSTL-3 (Series Stub Termination Logic) specifications for termination of DDR-SDRAM. The output, VTT, is capable of sinking and sourcing current while regulating the output voltage equal to VDDQ/2. The G2995 is designed to maintain the excellent load regulation and with fast response time to minimum the transition preventing shoot-through. The G2995 also incorporates two distinct power rails that separates the analog circuitry (AVIN) from the power output stage (PVIN). This power rails split can be utilized to reduce the internal power dissipation. And this also permits G2995 to provide a termination solution for the next generation of DDR-SDRAM (DDR II). RT RS MENORY CHIPSET VREF Figure 1. SSTL-Termination Scheme AVIN, PVIN AVIN and PVIN are two independent input supply pins for the G2995. AVIN is used to supply all the internal analog circuits. PVIN is only used to supply the output stage to create the regulated VTT. To keep the regulation successfully, AVIN should be equal to or larger than PVIN. Using a higher PVIN voltage will produce a larger sourcing capability from VTT. But the internal power loss will also increase and then the heat increases. If the junction temperature exceeds the thermal shutdown threshold than the G2995 will enter the shutdown state, where VTT is tri-state and VREF remains active. For SSTL-2 applications, the AVIN and PVIN can be short together at 2.5V to minimize the PCB complexity and to reduce the bypassing capacitors for the two supply pins separately. Series Stub Termination Logic (SSTL) was created to improve signal integrity of the data transmission across the memory bus. This termination scheme is essential to prevent data error from signal reflections while transmitting at high frequencies encountered with DDR-SDRAM. The most common form of termination is Class II single parallel termination. This involves one RS series resistor from the chipset to the memory and one RT termination resistor, both 25Ω typically. The resistors can be changed to scale the current requirements from the G2995. This implementation can be seen below in Figure 1. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 7 Global Mixed-mode Technology Inc. VDDQ A voltage divider of two 50kΩ is connected between VDDQ and ground, to create the internal reference voltage (VDDQ/2). This guarantees that VTT will track VDDQ/2 precisely. The optimal implementation of VDDQ is as a remote sensing. This can be achieved by connecting VDDQ directly to the 2.5V rail (SSTL-2 applications) at the DIMM instead of AVIN and PVIN. This will ensure that the reference voltage tracks the DDR memory rails precisely without a large voltage drop from the power lines. G2995 mal performance. The RDS of MOS will increase when the junction temperature increases. If the heat is not dealt with well, the maximum output current will be degraded. When the temperature exceeds the junction temperature, the thermal shutdown protection is activated. That will drive the VTT output into tri-state until the temperature returns below the hysteretic trigger point. Capacitors The G2995 does not require the capacitors for input stability, but it is recommended for improving the performance during large load transition to prevent the input power rail from dropping, especially for PVIN. The input capacitor for PVIN should be as close as possible. The typical recommended value is 50µF for AL electrolytic capacitors, 10uF with X5R for the ceramic capacitors. To prevent the excessive noise coupling into this device, an additional 0.1µF ceramic capacitor can be placed on the AVIN power rail for the better performance. Vsense The VSENSE pin is the feedback sensing pin of the operation amplifier which regulates the VTT voltage. In most motherboard applications, the termination resistors will connect VTT in a long plane. If using the remote sensing pin – VSENSE to the middle of the bus, the significant long-trace IR drop resulting in a termination voltage which is lower at one end than the other can be avoided. This will provide a better distribution across the entire termination bus. If the remote load regulation is not used, the VSENSE pin must still be connected to VTT for correct regulation. Care should be taken when a long VSENSE trace is implemented in close proximity to the memory. Noise pickup in the VSENSE trace can cause problems with precise regulation of VTT. A small 0.1µF ceramic capacitor placed next to the VSENSE pin can help to filter any high frequency signals and preventing errors. The output capacitor of the G2995 is suggested to use the capacitors with low ESR. Using the capacitors with low ESR (as ceramic, OS-CON, tantalum) will have the better transition performance which is with smaller voltage drop when the peak current occurring at the transition. As a general recommendation the output capacitor should be sized above 220µF with the low ESR for SSTL applications with DDR-SDRAM. Thermal Dissipation When the current is sinking to or sourcing from VTT, the G2995 will generate internal power dissipation resulting in the heat. Care should be taken to prevent the device from damages caused by the junction temperature exceeding the maximum rating. The maximum allowable internal temperature rise (TRMAX) can be calculated under the given maximum ambient temperature (TAMAX) of the application and the maximum allowable junction temperature (TJMAX). VREF VREF provides a buffered output of the internal reference voltage (VDDQ/2). It can support the reference voltage of Northbridge chipset and memory. For better performance, using an output bypass capacitor close this pin is more helpful for the noise. A ceramic capacitor in the range of 0.1µF to 0.01µF is recommended. VTT VTT is the regulated output that is used to terminate the bus resistors of DDR-SDRAM. It can precisely track the VDDQ/2 voltage with the sinking and sourcing current capability. The G2995 is designed to deliver 1.5A continuous current and peak current up to 3A with a fast transient response @ 2.5V supply rail. The maximum continuous current sourcing from VTT is a function of PVIN. Using a higher PVIN will increase the source current from VTT, but it also increase the internal power dissipation and reduce the efficiency. Although the G2995 can deliver the larger current, care should be taken for the thermal dissipation when larger current is required. The G2995 is packaged with Power-Pad to increase the power dissipation capability. When driving larger current, the larger heat-sink in the PCB is strongly recommended to have a better ther- TRMAX= TJMAX - TAMAX From this equation, the maximum power dissipation (PDMAX) of the G2995 can be calculated: PDMAX = TRMAX /θJA θJA of the G2995 will be dependent on several variables: the packages used, the thickness and size of the copper, the number of vias and the airflow. In the package, the G2995 use the SO-8 with Power-PAD to improve the θJA . If the layout of the PCB can put a larger size of copper to contact the Power-PAD of this device, the θJA will be further improved. The better θJA is not only protecting the device well, but also increasing the maximum current capability at the same ambient temperature. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 8 G2995 Global Mixed-mode Technology Inc. Typical Application Circuits ment the SSTL-2 termination scheme, it is recommended to connect all the input rails to 2.5V rail, as seen in Figure 2. This provides an optimal trade-off between power dissipation and component count. There are several application circuits shown in Figure 2 through 8 to illustrate some of the possible configurations of the G2995. Figure 2~4 are the SSTL-2 applications. For the majority of applications that imple- VREF VDDQ VDDQ=2.5V VREF=1.25V + CREF VDD=2.5V CIN AVIN VSENSE PVIN VTT + VTT=1.25V + GND COUT Figure 2. Recommended SSTL-2 Implementation device and improve the efficiency, but the disadvantage is the maximum continuous current sourcing from VTT is reduced. This configuration is applied when the power dissipation and efficiency are concerned. In Figure 3, the power rails are split. The power rail of the output stage (PVIN) can be as low as 1.8V, the power rail of the analog circuit (AVIN) is operated above 2V. The lower output stage power rail can lower the internal power dissipation when sourcing from the VDDQ VDDQ=2.5V VREF + VREF=1.25V CREF AVIN=1.8V or 5.5V PVIN=1.8V CIN AVIN VSENSE PVIN VTT + VTT=1.25V + GND COUT Figure 3. Lower Power Dissipation SSTL-2 Implementation In Figure 4, the power rail of the output stage (PVIN) is connected to 3.3V to increase the maximum continuous current sourcing from VTT. AVIN should be always equal to or larger than PVIN. This configuration can increase the source capability of this device, but the power dissipation increases at the same time. It should be more careful to prevent the junction temperature from exceeding the maximum rating. Because of this risk, it is not recommended to supply the output stage power rail (PVIN) with a voltage higher than a nominal 3.3V rail. VDDQ VDDQ=2.5V VREF + VREF=1.25V CREF AVIN=3.3V or 5V PVIN=3.3V CIN + AVIN VSENSE PVIN VTT GND VTT=1.25V + COUT Figure 4. SSTL-2 Implementation with higher voltage rails TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 9 G2995 Global Mixed-mode Technology Inc. is possible to use the G2995 in applications utilizing DDR-II memory. Figure 6 is used to increase the driving capability. The risk is the same as figure 4. In Figure 5 & 6, they are the application configurations of DDR-II SDRAM bus terminations. Figure 5 is the typical application scheme of DDR-II SDRAM. With the separate VDDQ pin and an internal resistor divider, it VREF VDDQ VDDQ=1.8V AVIN=1.8V or 5.5V AVIN VSENSE PVIN=1.8V PVIN VTT CIN + + VTT=0.9V + GND VREF=0.9V CREF COUT Figure 5. Recommended DDR-II Termination VREF VDDQ VDDQ=1.8V AVIN=3.3V or 5.5V AVIN VSENSE PVIN=3.3V PVIN VTT CIN + + VTT=0.9V + GND VREF=0.9V CREF COUT Figure 6. DDR-II Termination with higher voltage rails Figure 7 & 8 are used to scale the VTT to the wanted value when the standard voltages of SSTL-2 do not meet the requirements. Using R1 & R2, Figure 7 can VDDQ VDDQ VDD AVIN shift VTT up to VDDQ/2 * (1+R1/R2) and figure 8 can shift VTT down to VDDQ/2 * (1-R1/R2). VSENSE PVIN CIN + VTT VTT R1 + COUT R2 GND Figure 7. Increasing VTT by Level Shifting R2 VDDQ VDDQ VDD AVIN VSENSE R1 PVIN VTT VTT + CIN + GND COUT Figure 8. Decreasing VTT by Level Shifting TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 10 G2995 Global Mixed-mode Technology Inc. Package Information C E H L D θ 7 ° (4X) A2 A A1 y e B SOP-8L Package Note: 1. Package body sizes exclude mold flash and gate burrs 2. Dimension L is measured in gage plane 3. Tolerance 0.10mm unless otherwise specified 4. Controlling dimension is millimeter converted inch dimensions are not necessarily exact. 5. Followed from JEDEC MS-012 MIN. DIMENSION IN MM NOM. MAX. MIN. DIMENSION IN INCH NOM. MAX. A A1 1.35 0.10 1.60 ----- 1.75 0.25 0.053 0.004 0.063 ----- 0.069 0.010 A2 B C D E ----0.33 0.19 4.80 3.80 1.45 ----------------- ----0.51 0.25 5.00 4.00 ----0.013 0.007 0.189 0.150 0.057 ----------------- ----0.020 0.010 0.197 0.157 e H ----5.80 1.27 ----- ----6.20 ----0.228 0.050 ----- ----0.244 L y θ 0.40 ----- --------- 1.27 0.10 0.016 ----- --------- 0.050 0.004 0º ----- 8º 0º ----- 8º SYMBOL TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 11 G2995 Global Mixed-mode Technology Inc. C E1 E H D1 L D θ 7 ° (4X) A2 A A1 y e B SOP- 8L (FD) Package Note: 1. Package body sizes exclude mold flash and gate burrs 2. Dimension L is measured in gage plane 3. Tolerance 0.10mm unless otherwise specified 4. Controlling dimension is millimeter converted inch dimensions are not necessarily exact. 5. Followed from JEDEC MS-012 MIN. DIMENSION IN MM NOM. MAX. MIN. DIMENSION IN INCH NOM. A 1.45 1.50 1.55 0.057 0.059 0.061 A1 A2 0.00 ----- ----1.45 0.10 ----- 0.000 ----- ----0.057 0.004 ----- B C 0.33 0.19 --------- 0.51 0.25 0.013 0.007 --------- 0.020 0.010 D E 4.80 3.80 --------- 5.00 4.00 0.189 0.150 --------- 0.197 0.157 e H ----5.80 1.27 ----- ----6.20 ----0.228 0.050 ----- ----0.244 L 0.40 ----- 1.27 0.016 ----- 0.050 y θ ----- ----- 0.10 ----- ----- 0.004 D1 0º 2.22 --------- 8º 2.60 0º 0.087 --------- 8º 0.102 E1 2.60 ----- 2.98 0.102 ----- 0.117 SYMBOL MAX. Taping Specification PACKAGE Q’TY/REEL SOP-8 2,500 ea SOP-8 (FD) 2,500 ea Feed Direction Typical SOP Package Orientation GMT Inc. does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and GMT Inc. reserves the right at any time without notice to change said circuitry and specifications. TEL: 886-3-5788833 http://www.gmt.com.tw Ver: 1.7 May 10, 2005 12