® RT8877C Dual-Output PWM Controller for AMD SVI2 CPU Power Supply General Description Features The RT8877C is a 4 + 2 phases PWM controller. Moreover, it is compliant with AMD SVI2 Voltage Regulator Specification to support both CPU core (VDD) and Northbridge portion of the CPU (VDDNB). The RT8877C features CCRCOT (Constant Current Ripple Constant OnTime) with G-NAVP (Green-Native AVP), which is a Richtek's proprietary topology. G-NAVP makes it an easy setting controller to meet all AMD AVP (Active Voltage Positioning) VDD/VDDNB requirements. The droop is easily programmed by setting the DC gain of the error amplifier. With proper compensation, the load transient response can achieve optimized AVP performance. The controller also uses the interface to issue VOTF Complete and to send digitally encoded voltage and current values for the VDD and VDDNB domains. It can operate in single phase and diode emulation mode and reach up to 90% efficiency in different modes according to different loading conditions. The RT8877C provides special purpose offset capabilities by pin setting. The RT8877C also provides power good indication, over current indication (OCP_L) and dual OCP mechanism for AMD SVI2 CPU core and NB. It also features complete fault protection functions including over voltage, under voltage and negative voltage. 4/3/2/1-Phase (VDD) + 2/1/0-Phase (VDDNB) PWM Controller G-NAVPTM Topology Support Dynamic Load Line and Zero Load Line Diode Emulation Mode at Light Load Condition SVI2 Interface to Comply AMD Power Management Protocol Build-in ADC for VOUT and IOUT Reporting Immediate OV, UV and NV Protections and UVLO Programmable Dual OCP Mechanism 0.5% DAC Accuracy Fast Transient Response Power Good Indicator Over Current Indicator 52-Lead WQFN Package RoHS Compliant and Halogen Free Applications AMD SVI2 CPU Desktop Computer Simplified Application Circuit RT8877C OCP_L PWM1 RT9624A MOSFET PWM2 RT9624A MOSFET PWM3 RT9624A MOSFET SVC To CPU SVD SVT PWM4 RT9624A MOSFET PWMA1 RT9624A MOSFET PWMA2 RT9624A MOSFET Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 VVDD VVDDNB is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8877C Ordering Information Pin Configurations RT8877C Note : Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Marking Information RT8877CZQW : Product Number RT8877C ZQW YMDNN YMDNN : Date Code 52 51 50 49 48 47 46 45 44 43 42 41 40 PWM4 TONSET ISEN2P ISEN2N ISEN1N ISEN1P ISEN3P ISEN3N ISEN4N ISEN4P VSEN FB COMP 1 39 2 38 3 37 4 36 5 35 6 7 34 GND 33 8 32 9 10 31 30 53 11 29 12 28 13 27 PGOOD PGOODA EN ISENA1P ISENA1N ISENA2N ISENA2P VSENA FBA COMPA IBIAS VCC OCP_L 14 15 16 17 18 19 20 21 22 23 24 25 26 RGND IMON V064 IMONA VDDIO PWROK SVC SVD SVT OFS OFSA SET1 SET2 Package Type QW : WQFN-52L 6x6 (W-Type) Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) PWM3 PWM2 PWM1 NC NC NC DVD NC NC NC PWMA1 PWMA2 TONSETA (TOP VIEW) WQFN-52L 6x6 Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Functional Pin Description Pin No. Pin Name 1, 52, 51, 50 Pin Function PWM4 to PWM1 PWM Outputs for Channel 1, 2, 3 and 4 of VDD Controller. TONSET VDD Controller On-Time Setting. Connect this pin to the converter input voltage, Vin, through a resistor, RTON, to set the on-time of UGATE and also the output voltage ripple of VDD controller. 5, 4, 8, 9 ISEN1N to ISEN4N Negative Current Sense Input of Channel 1, 2, 3 and 4 for VDD Controller. 6, 3, 7, 10 ISEN1P to ISEN4P Positive Current Sense Input of Channel 1, 2, 3 and 4 for VDD Controller. 11 VSEN VDD Controller Voltage Sense Input. This pin is connected to the terminal of VDD controller output voltage. 12 FB Output Voltage Feedback Input of VDD Controller. This pin is the negative input of the error amplifier for the VDD controller. 13 COMP 14 RGND 15 IMON 16 V064 17 IMONA 18 VDDIO 19 PWROK 20 SVC Serial VID Clock Input from Processor. 21 SVD Serial VID Data input from Processor. This pin is a serial data line. 22 SVT Serial VID Telemetry Input from VR. This pin is a push-pull output. 23 OFS Over Clocking Offset Setting for the VDD Controller. 24 OFSA Over Clocking Special Purpose Offset Setting for the VDDNB Controller. 25 SET1 OCP_TDC threshold setting individually for VDD and VDDNB controllers and also the internal ramp slew rate setting (RSET and RSETA) individually for VDD and VDDNB controllers 26 SET2 Quick response threshold setting individually for VDD and VDDNB controllers (QRTH and QRTHA) and also the OCP_TDC trigger delay time setting for both controllers and over clocking offset enable setting. 27 OCP_L Over Current Indicator for Dual OCP Mechanism. This pin is an open drain output. 28 VCC Controller Power Supply Input. Connect this pin to 5V with an 1F or greater ceramic capacitor for decoupling. 2 Error Amplifier Output Pin of the VDD Controller. Return Ground of VDD and VDDNB Controller. This pin is the common negative input of output voltage differential remote sense for VDD and VDDNB controllers. Current Monitor Output for the VDD Controller. This pin outputs a voltage proportional to the output current. Fixed 0.64V Reference Voltage Output. This voltage is only used to offset the output voltage of IMON pin and IMONA pin. Connect a 0.47F capacitor from this pin to GND. Current Monitor Output for the VDDNB Controller. This pin outputs a voltage proportional to the output current. Processor memory interface power rail and serves as the reference for PWROK, SVD, SVC and SVT. This pin is used by the VR to reference the SVI pins. System Power Good Input. If PWROK is low, the SVI interface is disabled and VR returns to BOOT-VID state with initial load line slope and initial offset. If PWROK is high, the SVI interface is running and the DAC decodes the received serial VID codes to determine the output voltage. Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8877C Pin No. Pin Name Pin Function 29 IBIAS Internal Bias Current Setting. Connect only a 100k resistor from this pin to GND to generate bias current for internal circuit. Place this resistor as close to IBIAS pin as possible. 30 COMPA Error Amplifier Output of the VDDNB Controller. 31 FBA Output Voltage Feedback Input of VDDNB Controller. This pin is the negative input of the error amplifier for the VDDNB controller. 32 VSENA VDDNB Controller Voltage Sense Input. This pin is connected to the terminal of VDDNB controller output voltage. 37 ISENA2P, ISENA1P ISENA2N, ISENA1N EN 38 PGOODA Power Good Indicator for the VDDNB Controller. This pin is an open drain output. 39 PGOOD Power Good Indicator for the VDD Controller. This pin is an open drain output. TONSETA VDDNB Controller On-Time Setting. Connect this pin to the converter input voltage, Vin, through a resistor, RTONNB, to set the on-time of UGATE_VDDNB and also the output voltage ripple of VDDNB controller. PWMA2, PWMA1 PWM Output for Channel 1 and 2 of VDDNB Controller. 33, 36 34, 35 40 41, 42 Positive Current Sense Input of Channel 1 and 2 for VDDNB Controller. Negative Current Sense Input of Channel 1 and 2 for VDDNB Controller. Controller Enable pin. A logic high signal enables the controller. 43, 44, 45, 47, 48, 49 46 NC No Internal Connection. DVD 53 (Exposed Pad) GND External Driver Power Supply Input Voltage Detection Pin. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C PGOODA OCP_L PGOOD VCC DVD EN PWROK VDDIO SVT SVD SVC VSEN VSENA OFSA IMONI IMONAI OFS SET2 SET1 Function Block Diagram UVLO MUX GND ADC OFS/OFSA SVI2 Interface Configuration Registers Control Logic IBIAS RSET/RSETA From Control Logic RGND TONSETA OCP Threshold DAC Soft-Start & Slew Rate Control VSETA ERROR AMP + Offset Cancellation + - + PWM CMPA PWMA1 QRA - + x2 - ISENA1N IBA1 V064 + 0.4 - RSETA Current mirror ISENA2P + x2 - ISENA2N Average IBA2 Current Balance IMONAI IBA1 IMONA OCP_TDCA, OCP_SPIKEA From Control Logic + OCA To Protection Logic - VSENA VSET FB OV/UV/NV TONSET ERROR AMP + Offset Cancellation + - + PWM1 PWM CMP - Current mirror ISEN1P ISEN1N + x1 - ISEN2P + x1 - PWM3 PWM4 TON IB1 + 0.4 - RSET Current mirror IB2 Average Current Balance IMONI Current mirror + x1 - PWM2 TON GEN QR COMP ISEN3N IBA2 DAC Soft-Start & Slew Rate Control ISEN3P PWMA2 Current mirror ISENA1P ISEN2N TON GENA TONA FBA COMPA RGND Loop Control Protection Logic Load Line /Load Line A IB1 IB2 IB3 IB4 IB3 Current mirror ISEN4P ISEN4N + x1 - IB4 OCP_TDC, OCP_SPIKE + OC - VSEN To Protection Logic OV/UV/NV IMON V064 Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8877C Operation MUX and ADC Error Amp The MUX supports the inputs from SET1, SET2, OFS, OFSA, IMON, IMONA, VSEN, or VSENA. The ADC converts these analog signals to digital codes for reporting or performance adjustment. Error amplifier generates COMP/COMPA signal by the difference between VSET/VSETA and FB/FBA. SVI2 Interface The SVI2 interface uses SVC, SVD, and SVT pins to communicate with CPU. RT8877C's performance and behavior can be adjusted by commands sent by CPU or platform. Offset cancellation This block cancels the output offset voltage from voltage ripple and current ripple to achieve accurate output voltage. PWM CMPx The PWM comparator compares COMP signal and current feedback signal to generate a signal for TONGENx. UVLO TONGEN/TONGENA The UVLO detects DVD and VCC pin voltages for under voltage lockout protection and power on reset operation. This block generates an on-time pulse which high interval is based on the on-time setting and current balance. Loop Control Protection Logic Current Balance Loop control protection logic detects EN and UVLO signals to initiate soft-start function and control PGOOD, PGOODA and OCP_L signals after soft-start is finished. When OCP event is triggered, the OCP_L pin voltage will be pulled low. Per-phase current is sensed and adjusted by adjusting on-time of each phase to achieve current balance for each phase. DAC The DAC receives VID codes from the SVI2 control logic to generate an internal reference voltage (VSET/VSETA) for controller. Soft-Start and Slew-Rate Control OC/OV/UV/NV VSEN/VSENA and output current are sensed for over current, over voltage, under voltage, and negative voltage protection. RSET/RSETA The Ramp generator is designed to improve noise immunity and reduce jitter. This block controls the slew rate of the internal reference voltage when output voltage changes. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Table 1. Serial VID Codes SVID [7:0] Voltage (V) SVID [7:0] Voltage (V) SVID [7:0] Voltage (V) SVID [7:0] Voltage (V) 0000_0000 1.55000 0010_0111 1.30625 0100_1110 1.06250 0111_0101 0.81875 0000_0001 1.54375 0010_1000 1.30000 0100_1111 1.05625 0111_0110 0.81250 0000_0010 1.53750 0010_1001 1.29375 0101_0000 1.05000 0111_0111 0.80625 0000_0011 1.53125 0010_1010 1.28750 0101_0001 1.04375 0111_1000 0.80000 0000_0100 1.52500 0010_1011 1.28125 0101_0010 1.03750 0111_1001 0.79375 0000_0101 1.51875 0010_1100 1.27500 0101_0011 1.03125 0111_1010 0.78750 0000_0110 1.51250 0010_1101 1.26875 0101_0100 1.02500 0111_1011 0.78125 0000_0111 1.50625 0010_1110 1.26250 0101_0101 1.01875 0111_1100 0.77500 0000_1000 1.50000 0010_1111 1.25625 0101_0110 1.01250 0111_1101 0.76875 0000_1001 1.49375 0011_0000 1.25000 0101_0111 1.00625 0111_1110 0.76250 0000_1010 1.48750 0011_0001 1.24375 0101_1000 1.00000 0111_1111 0.75625 0000_1011 1.48125 0011_0010 1.23750 0101_1001 0.99375 1000_0000 0.75000 0000_1100 1.47500 0011_0011 1.23125 0101_1010 0.98750 1000_0001 0.74375 0000_1101 1.46875 0011_0100 1.22500 0101_1011 0.98125 1000_0010 0.73750 0000_1110 1.46250 0011_0101 1.21875 0101_1100 0.97500 1000_0011 0.73125 0000_1111 1.45625 0011_0110 1.21250 0101_1101 0.96875 1000_0100 0.72500 0001_0000 1.45000 0011_0111 1.20625 0101_1110 0.96250 1000_0101 0.71875 0001_0001 1.44375 0011_1000 1.20000 0101_1111 0.95625 1000_0110 0.71250 0001_0010 1.43750 0011_1001 1.19375 0110_0000 0.95000 1000_0111 0.70625 0001_0011 1.43125 0011_1010 1.18750 0110_0001 0.94375 1000_1000 0.70000 0001_0100 1.42500 0011_1011 1.18125 0110_0010 0.93750 1000_1001 0.69375 0001_0101 1.41875 0011_1100 1.17500 0110_0011 0.93125 1000_1010 0.68750 0001_0110 1.41250 0011_1101 1.16875 0110_0100 0.92500 1000_1011 0.68125 0001_0111 1.40625 0011_1110 1.16250 0110_0101 0.91875 1000_1100 0.67500 0001_1000 1.40000 0011_1111 1.15625 0110_0110 0.91250 1000_1101 0.66875 0001_1001 1.39375 0100_0000 1.15000 0110_0111 0.90625 1000_1110 0.66250 0001_1010 1.38750 0100_0001 1.14375 0110_1000 0.90000 1000_1111 0.65625 0001_1011 1.38125 0100_0010 1.13750 0110_1001 0.89375 1001_0000 0.65000 0001_1100 1.37500 0100_0011 1.13125 0110_1010 0.88750 1001_0001 0.64375 0001_1101 1.36875 0100_0100 1.12500 0110_1011 0.88125 1001_0010 0.63750 0001_1110 1.36250 0100_0101 1.11875 0110_1100 0.87500 1001_0011 0.63125 0001_1111 1.35625 0010_0110 1.11250 0110_1101 0.86875 1001_0100 0.62500 0010_0000 1.35000 0100_0111 1.10625 0110_1110 0.86250 1001_0101 0.61875 0010_0001 1.34375 0100_1000 1.10000 0110_1111 0.85625 1001_0110 0.61250 0010_0010 1.33750 0100_1001 1.09375 0111_0000 0.85000 1001_0111 0.60625 0010_0011 1.33125 0100_1010 1.08750 0111_0001 0.84375 1001_1000 0.60000 0010_0100 1.32500 0100_1011 1.08125 0111_0010 0.83750 1001_1001 0.59375 0010_0101 1.31875 0100_1100 1.07500 0111_0011 0.83125 1001_1010 0.58750 0010_0110 1.31250 0100_1101 1.06875 0111_0100 0.82500 1001_1011 0.58125 Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8877C SVID [7:0] Voltage (V) SVID [7:0] Voltage (V) SVID [7:0] Voltage (V) SVID [7:0] Voltage (V) 1001_1100 0.57500 1011_0101 * 0.41875 1100_1110 * 0.26250 1110_0111* 0.10625 1001_1101 0.56875 1011_0110 * 0.41250 1100_1111 * 0.25625 1110_1000* 0.10000 1001_1110 0.56250 1011_0111 * 0.40625 1101_0000 * 0.25000 1110_1001* 0.09375 1001_1111 0.55625 1011_1000 * 0.40000 1101_0001 * 0.24375 1110_1010* 0.08750 1010_0000 0.55000 1011_1001 * 0.39375 1101_0010 * 0.23750 1110_1011* 0.08125 1010_0001 0.54375 1011_1010 * 0.38750 1101_0011 * 0.23125 1110_1100* 0.07500 1010_0010 0.53750 1011_1011 * 0.38125 1101_0100 * 0.22500 1110_1101* 0.06875 1010_0011 0.53125 1011_1100 * 0.37500 1101_0101 * 0.21875 1110_1110* 0.06250 1010_0100 0.52500 1011_1101 * 0.36875 1101_0110 * 0.21250 1110_1111* 0.05625 1010_0101 0.51875 1011_1110 * 0.36250 1101_0111 * 0.20625 1111_0000* 0.05000 1010_0110 0.51250 1011_1111 * 0.35625 1101_1000 * 0.20000 1111_0001* 0.04375 1010_0111 0.50625 1100_0000 * 0.35000 1101_1001 * 0.19375 1111_0010* 0.03750 1010_1000 * 0.50000 1100_0001 * 0.34375 1101_1010 * 0.18750 1111_0011* 0.03125 1010_1001 * 0.49375 1100_0010 * 0.33750 1101_1011 * 0.18125 1111_0100* 0.02500 1010_1010 * 0.48750 1100_0011 * 0.33125 1101_1100 * 0.17500 1111_0101* 0.01875 1010_1011 * 0.48125 1100_0100 * 0.32500 1101_1101 * 0.16875 1111_0110* 0.01250 1010_1100 * 0.47500 1100_0101 * 0.31875 1101_1110 * 0.16250 1111_0111* 0.00625 1010_1101 * 0.46875 1100_0110 * 0.31250 1101_1111 * 0.15625 1111_1000* 0.00000 1010_1110 * 0.46250 1100_0111 * 0.30625 1110_0000* 0.15000 1111_1001* OFF 1010_1111 * 0.45625 1100_1000 * 0.30000 1110_0001* 0.14375 1111_1010* OFF 1011_0000 * 0.45000 1100_1001 * 0.29375 1110_0010* 0.13750 1111_1011* OFF 1011_0001 * 0.44375 1100_1010 * 0.28750 1110_0011* 0.13125 1111_1100* OFF 1011_0010 * 0.43750 1100_1011 * 0.28125 1110_0100* 0.12500 1111_1101* OFF 1011_0011 * 0.43125 1100_1100 * 0.27500 1110_0101* 0.11875 1111_1110* OFF 1011_0100 * 0.42500 1100_1101 * 0.26875 1110_0110* 0.11250 1111_1111* OFF * Indicates TOB is 80mV for this VID code; unconditional VR controller stability required at all VID codes Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Table 2. SET1 Pin Setting for VDD Controller RSET SET1 Pin Voltage Before Current Injection VSET1 (mV) 34 145% 836 145% 59 130% 861 130% 115% 886 100% 911 135 85% 936 85% 160 70% 961 70% 235 145% 1036 145% 260 130% 1061 130% 115% 1086 100% 1112 335 85% 1137 85% 360 70% 1162 70% 435 145% 1237 145% 460 130% 1262 130% 115% 1287 100% 1312 535 85% 1337 85% 560 70% 1362 70% 636 145% 1437 145% 661 130% 1462 130% 115% 1487 100% 1512 736 85% 1537 85% 761 70% 1562 70% SET1 Pin Voltage Before Current Injection VSET1 (mV) OCP_TDC (Respect to OCP_SPIKE) 85 110 285 310 485 510 686 711 45% 50% 55% 60% Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 OCP_TDC (Respect to OCP_SPIKE) 65% 70% 75% Disable RSET 115% 100% 115% 100% 115% 100% 115% 100% is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8877C Table 3. SET1 Pin Setting for VDDNB Controller SET1 Pin Voltage OCP_TDCA Difference VSET1 (Respect to (Before and After OCP_SPIKEA) Current Injection) (mV) RSETA SET1 Pin Voltage OCP_TDCA Difference VSET1 (Respect to (Before and After OCP_SPIKEA) Current Injection) (mV) RSETA 34 145% 836 145% 59 130% 861 130% 115% 886 100% 911 135 85% 936 85% 160 70% 961 70% 235 145% 1036 145% 260 130% 1061 130% 115% 1086 100% 1112 335 85% 1137 85% 360 70% 1162 70% 435 145% 1237 145% 460 130% 1262 130% 115% 1287 100% 1312 535 85% 1337 85% 560 70% 1362 70% 636 145% 1437 145% 661 130% 1462 130% 115% 1487 100% 1512 736 85% 1537 85% 761 70% 1562 70% 85 110 285 310 485 510 686 711 45% 50% 55% 60% Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 65% 70% 75% Disable 115% 100% 115% 100% 115% 100% 115% 100% is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Table 4. SET2 Pin Setting SET2 Pin Voltage Before Current Injection VSET2 (mV) QRTH (for VDD) OCPTRGDELAY [1:0] OCPTRGDELAY (for VDD/VDDNB) 00 10ms 01 20ms 10 30ms 172 11 40ms 222 00 10ms 01 20ms 10 30ms 373 11 40ms 423 00 10ms 01 20ms 10 30ms 573 11 40ms 623 00 10ms 01 20ms 10 30ms 773 11 40ms 823 00 10ms 01 20ms 10 30ms 974 11 40ms 1024 00 10ms 01 20ms 10 30ms 1174 11 40ms 1224 00 10ms 01 20ms 10 30ms 1375 11 40ms 1425 00 10ms 01 20ms 10 30ms 11 40ms 19 72 122 272 323 473 523 673 723 874 924 1074 1124 1274 1324 1475 1525 1575 Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 Disable 35mV 39mV 43mV 47mV 51mV 55mV 60mV is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT8877C Table 5. Quick Response Threshold for VDDNB Controller SET2 Pin Voltage Difference VSET2 (Before and After Current Injection) (mV) QRTH [2:0] QRTHA (for VDDNB) 19 000 Disable 72 001 35mV 122 010 39mV 011 43mV 100 47mV 272 101 51mV 323 110 55mV 111 59mV 000 Disable 473 001 35mV 523 010 39mV 011 43mV 100 47mV 673 101 51mV 723 110 55mV 773 111 59mV 823 000 Disable 874 001 35mV 924 010 39mV 011 43mV 100 47mV 1074 101 51mV 1124 110 55mV 111 59mV 000 Disable 1274 001 35mV 1324 010 39mV 011 43mV 100 47mV 1475 101 51mV 1525 110 55mV 1575 111 59mV OFSENABLE 172 0 222 373 423 0 573 1 623 974 0 1024 1174 1224 1375 1425 Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 OFSAENABLE 1 1 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Absolute Maximum Ratings (Note 1) VCC to GND --------------------------------------------------------------------------------------------------------RGND to GND ------------------------------------------------------------------------------------------------------TONSET to GND ---------------------------------------------------------------------------------------------------Other Pins -----------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C WQFN-52L 6x6 ----------------------------------------------------------------------------------------------------- 3.77W Package Thermal Resistance (Note 2) WQFN-52L 6x6, θJA ------------------------------------------------------------------------------------------------ 26.5°C/W WQFN-52L 6x6, θJC ----------------------------------------------------------------------------------------------- 6.5°C/W Junction Temperature ---------------------------------------------------------------------------------------------- 150°C Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------ 260°C Storage Temperature Range ------------------------------------------------------------------------------------- −65°C to 150°C ESD Susceptibility (Note 3) HBM (Human Body Model) --------------------------------------------------------------------------------------- 2kV Recommended Operating Conditions −0.3V to 6.5V −0.3V to 0.3V −0.3V to 28V −0.3V to (VCC + 0.3V) (Note 4) Supply Voltage, VCC ---------------------------------------------------------------------------------------------- 4.5V to 5.5V Junction Temperature Range ------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VCC = 5V, TA = 25°C, unless otherwise specified) Parameter Input Power Supply Supply Current Shutdown Current Reference and DAC DC Accuracy Symbol Test Conditions IVCC ISHDN EN = 3V, Not Switching EN = 0V VFB VFB = 1.0000 1.5500 (No Load, CCM Mode) VFB = 0.8000 1.0000 VFB = 0.3000 0.8000 VFB = 0.2500 0.3000 RGND Current RGND Current Slew Rate Dynamic VID Slew Rate Error Amplifier Input Offset DC Gain VEAOFS ADC Gain-Bandwidth Product Output Voltage Range Maximum Source Current GBW CLOAD = 5pF VCOMP IEA, SRC Maximum Sink Current IEA, SNK January 2014 Typ Max Unit --- --- 12 5 mA A 0.5 0 0.5 %SVID 5 8 80 0 0 0 5 8 80 mV -- -- 200 A IRGND EN = 3V, Not Switching SR SetVID Fast 7.5 12 -- mV/s RL = 47k -70 -80 2 -- mV dB -0.3 1 10 --- -3.6 -- MHz V mA 1 -- -- mA Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 Min is a registered trademark of Richtek Technology Corporation. www.richtek.com 13 RT8877C Parameter Symbol Test Conditions Min Typ Max Unit 0.2 -- 0.2 mV Current Mirror Gain for CORE AMIRROR, VDD 97 -- 103 % Current Mirror Gain for NB AMIRROR, VDDNB 194 -- 206 % Impedance at Negative Input RISENxN 1 -- -- M Impedance at Positive Input Internal Sum Current Sense DC Gain for CORE Internal Sum Current Sense DC Gain for NB Maximum Source Current RISENxP 1 -- -- M Current Sense Amplifier Input Offset Voltage VOSCS Ai, VDD VDD Controller -- 0.4 -- V/V Ai, VDDNB VDDNB Controller -- 0.8 -- V/V ICS, SRC 0 < VFB < 2.35 100 -- -- A Maximum Sink Current ICS, SNK 0 < VFB < 2.35 12 -- -- A Zero Current Detection Zero Current Detection Threshold Ton Setting VZCD_TH VZCD_TH = GND VPHASEx -- 1 -- mV TONSETx Pin Minimum Voltage VTON, MIN -- 0.5 -- V TONSETx Ton TON IRTON = 80A, VFB = 1.1V 270 305 340 ns TONSETx Input Current Range IRTON VFB = 1.1V 25 -- 280 A Minimum TOFF TOFF -- 250 -- ns 1.97 2 2.03 V 0.61 0.64 0.67 V 800 -- -- A IBIAS IBIAS Pin Voltage VIBIAS RIBIAS = 100k V064 Reference Voltage Output V064 Sink Current Capability IV064, SNK Source Current Capability IV064, SRC -- -- 100 A VFB Limit VFB, LIMIT 0 -- 2.35 V OFS Update Rate FOFS -- 50 -- kHz Board Offset Resolution VOFS -- 6.25 -- mV Logic-High VIH_EN 2 -- -- Logic-Low VIL_EN -- -- 0.8 Leakage Current of EN ILEK_EN 1 -- 1 Logic-High SVC, SVD, SVT, PWROK Logic-Low VIH_SVI Respect to VDDIO 70 -- 100 VIL_SVI Respect to VDDIO 0 -- 35 Hysteresis of SVC, SVD, SVT, PWROK VHYS_SVI Respect to VDDIO 10 -- -- V064 = 0.64V Board OFSx Logic Inputs EN Input Voltage Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 14 V A % % is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Parameter Symbol Test Conditions Min Typ Max Unit 4 4.2 4.4 V -- 100 -- mV -- 3 -- s 275 325 375 mV -- 1 -- s 375 325 275 mV -- 3 -- s -- 0 -- mV -- 10 -- A -- 1 -- s 162 180 198 A 6 -- 12 s 12 -- 24 s 0 -- 0.2 V 2 -- -- s Protection Under Voltage Lockout Threshold VUVLO Under Voltage Lockout Hysteresis VUVLO Under Voltage Lockout Delay T UVLO Over Voltage Protection Threshold VOVP Over Voltage Protection Delay T OVP Under Voltage Protection Threshold VUVP Under Voltage Protection Delay T UVP Negative Voltage Protection Threshold VNV Per Phase OCP Threshold IOCP_PERPHASE Delay of Per Phase OCP T PHOCP OCP_SPIKE Threshold IOCP_SPIKE OCP_SPIKE Action Delay OCP_TDC Action Delay VCC Falling edge VCC Rising above UVLO Threshold VSEN Rising above Threshold VSEN Falling below Threshold IISENxN Per-Phase OCP Threshold. DCR = 0.95m, RSENSE = 680, RIMON = 10k T OCPSPIKE _ACTION_DLY T OCPTDC _ACTION_DLY OCP_L, PGOOD and PGOODA Output Low Voltage at OCP_L VOCP_L OCP_L Assertion Time T OCP_L Output Low Voltage at PGOOD, PGOODA VPGOOD, VPGOODA , IPGOOD = 4mA, IPGOODA = 4mA 0 -- 0.2 V PGOOD and PGOODA Threshold Voltage VTH_PGOOD VTH_PGOODA Respect to VBOOT -- 300 -- mV PGOOD and PGOODA Delay Time Current Report Maximum Reported Current (FFh = OCP) T PGOOD T PGOODA VSEN = VBOOT to PGOOD/PGOODA High 70 100 130 s -- 100 -- %IDD_SP IKE_OCP Minimum Reported Current (00h) -- 0 -- %IDD_SP IKE_OCP IDDSpike Current Accuracy -- -- 3 % IOCP_L = 4mA Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 15 RT8877C Parameter Symbol Test Conditions Min Typ Max Unit Maximum Reported Voltage (0_00h) -- 3.15 -- V Minimum Reported Voltage (1_F8h) -- 0 -- V Voltage Accuracy 2 -- 2 LSB QRTHx [2:0] = [001] -- 35 -- mV VQRTH, MAXx QRTHx [2:0] = [111] -- 60 -- mV PWMx Source Resistance R PWM_SRC -- 20 -- PWMx Sink Resistance R PWM_SNK -- 10 -- Voltage Report QR Setting of VDD and VDDNB Quick Response Threshold Voltage Setting Range Minimum Value Quick Response Threshold Voltage Setting Range Maximum Value VQRTH, MINx PWM Driving Capability Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 16 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Typical Application Circuit 510k 12V 46 300k 0.1µF DVD VCC5 1µF 2.2 5V VDDIO 28 VCC 0.1µF 20k VCC5 VCC5 VCC5 VCC5 23 OFS 24 OFSA 20k 124k 124k 1k 25 SET1 1.27k 1k 26 SET2 43.2k 470 6.32k 0.1µF 6.32k VIN 2 TONSET 0.1µF 1 VIN RTONNB 147k 40 IBIAS Chip Enable 37 82pF 39pF 10k 32.32k 100 100 270µF 0 0.36μH / 0.72m VVDDNB LOAD 2.2 820µF x3 1µF 510 UGATE PGND PHASE 0 1 16 11.5k 15 RIMON 2.34k RNTC 100k 17 RIMONA 2.84k RNTC 100k COMPA 31 FBA 14 RGND COMP 13 42 0 PWMA1 5V PWM1 50 0.36μH / 0.72m 1µF 510 UGATE PGND PHASE 0 1 ISENA1P 35 ISENA1N ISEN1N 5 PWM2 51 5V VIN ISENA2P 34 ISENA2N ISEN2P ISEN2N PGND UGATE PWM 2.2 270µF 0 0.36μH / 0.72m 510 1µF VVDD 820µF x8 LOAD 0.1µF 2.2 VIN 270µF 0 0.36μH / 0.72m PHASE 0 1 510 1µF RSENSE2 560 BOOT UGATE PGND PHASE 0 VIN 12V VCC VCC 1µF PWM LGATE EN RT9624A 1µF 1 PWM4 PWM3 52 5V PWM 5V BOOT PGND UGATE 0.1µF 2.2 270µF 0 0.36μH / 0.72m PHASE LGATE EN RT9624A 0 1 510 1µF 3.3nF 3.3nF 10 RSENSE4 560 Copyright © 2014 Richtek Technology Corporation. All rights reserved. January 2014 1 3 4 12V 0.1µF DS8877C-01 BOOT LGATE EN RT9624A 5V 33 1 0 3.3nF RSENSEA2 560 510 100 0.36μH / 0.72m PHASE 12V 3.3nF 1µF 100 270µF 0 RSENSE1 560 VCC PWMA2 0.1µF 2.2 3.3nF ISEN1P 6 1µF 41 BOOT PGND UGATE PWM 1µF PWM LGATE EN RT9624A VSS_SENSE LGATE EN RT9624A 5V VCC BOOT VVDD_SENSE VIN 1µF 12V 270µF 10k VCC 36 2.2 82pF 12V RSENSEA1 560 0.1µF 27pF FB 12 3.3nF VIN 13.739k 50.65k 1µF PWM LGATE EN RT9624A 0.47µF 15.82k GND 53 (Exposed Pad) VCC BOOT To CPU 30 12V 0.1µF 10k RIBIAS 29 100k VSEN 11 VSS_SENSE VIN 3.3V 10.94k IMONA EN 32 VSENA VVDDNB_SENSE IMON TONSETA 0.1µF 4.7k 10k 20 SVC 21 SVD 22 SVT 0.1µF RTON 150k 1 4.7k OCP_L 27 19 PWROK PGOOD 39 PGOODA 38 V064 0 2.2 RT8877C VDDIO 18 9 ISEN4P ISEN3P 7 ISEN4N ISEN3N 8 RSENSE3 560 is a registered trademark of Richtek Technology Corporation. www.richtek.com 17 RT8877C Typical Operating Characteristics CORE VR Power Off from EN CORE VR Power On from EN VVDD (500mV/Div) EN (5V/Div) VVDD (500mV/Div) EN (5V/Div) PGOOD (5V/Div) PGOOD (5V/Div) UGATE1 (20V/Div) UGATE1 (20V/Div) Boot VID = 0.8V Time (200μs/Div) Time (200μs/Div) CORE VR OCP_TDC CORE VR OCP_SPIKE I LOAD (200A/Div) I LOAD (250A/Div) PGOOD (5V/Div) OCP_L (2V/Div) PGOOD (5V/Div) OCP_L (2V/Div) UGATE1 (20V/Div) UGATE1 (20V/Div) ILOAD = 80A to 160A ILOAD = 50A to 200A Time (4ms/Div) Time (8μs/Div) CORE VR OVP and NVP CORE VR UVP VVDD (500mV/Div) PGOOD (5V/Div) UGATE1 (50V/Div) LGATE1 (20V/Div) VID = 1.1V Time (20μs/Div) Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 18 Boot VID = 0.8V VVDD (500mV/Div) PGOOD (5V/Div) UGATE1 (50V/Div) LGATE1 (20V/Div) VID = 1.1V Time (10μs/Div) is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C CORE VR Dynamic VID Up CORE VR Dynamic VID Up VVDD (500mV/Div) VVDD (500mV/Div) I LOAD (22A/Div) SVD (2V/Div) SVT (2V/Div) I LOAD (55A/Div) SVD (2V/Div) SVT (2V/Div) VID = 0.4V to 1V, ILOAD = 11A Time (20μs/Div) Time (20μs/Div) CORE VR Dynamic VID Up CORE VR Dynamic VID Up VVDD (500mV/Div) VVDD (500mV/Div) I LOAD (55A/Div) SVD (2V/Div) SVT (2V/Div) I LOAD (55A/Div) SVD (2V/Div) SVT (2V/Div) VID = 1V to 1.1V, ILOAD = 55A VID = 1V to 1.2V, ILOAD = 55A Time (20μs/Div) Time (20μs/Div) CORE VR Dynamic VID Up CORE VR Load Transient VVDD (500mV/Div) VVDD (100mV/Div) I LOAD (55A/Div) SVD (2V/Div) SVT (2V/Div) I LOAD (120A/Div) VID = 1V to 1.4V, ILOAD = 55A Time (20μs/Div) Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 VID = 1V to 1.06875V, ILOAD = 55A January 2014 fLOAD = 10kHz, ILOAD = 55A to 150A Time (4μs/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 19 RT8877C NB VR Power On from EN CORE VR Load Transient V VDDNB (500mV/Div) EN (5V/Div) VVDD (100mV/Div) PGOODA (5V/Div) I LOAD (120A/Div) fLOAD = 10kHz, ILOAD = 150A to 55A UGATEA1 (20V/Div) Boot VID = 0.8V Time (4μs/Div) Time (200μs/Div) NB VR Power Off from EN NB VR OCP_TDC I LOAD (100A/Div) V VDDNB (500mV/Div) EN (5V/Div) PGOODA (5V/Div) PGOODA (5V/Div) OCP_L (2V/Div) UGATEA1 (20V/Div) UGATEA1 (20V/Div) Boot VID = 0.8V ILOAD = 30A to 60A Time (200μs/Div) Time (4ms/Div) NB VR OCP_SPIKE NB VR OVP and NVP I LOAD (100A/Div) PGOODA (5V/Div) OCP_L (2V/Div) UGATEA1 (20V/Div) ILOAD = 20A to 80A Time (8μs/Div) Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 20 V VDDNB (500mV/Div) PGOODA (5V/Div) UGATEA1 (50V/Div) LGATEA1 (20V/Div) VID = 1.1V Time (20μs/Div) is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C NB VR Dynamic VID Up NB VR UVP V VDDNB (500mV/Div) V VDDNB (500mV/Div) PGOODA (5V/Div) UGATEA1 (50V/Div) LGATEA1 (20V/Div) VID = 1.1V I LOAD (9A/Div) SVD (2V/Div) SVT (2V/Div) Time (10μs/Div) Time (20μs/Div) NB VR Dynamic VID Up NB VR Dynamic VID Up V VDDNB (500mV/Div) V VDDNB (500mV/Div) I LOAD (21A/Div) SVD (2V/Div) SVT (2V/Div) I LOAD (21A/Div) SVD (2V/Div) SVT (2V/Div) VID = 1V to 1.06875V, ILOAD = 20.5A VID = 1V to 1.1V, ILOAD = 20.5A Time (20μs/Div) Time (20μs/Div) NB VR Dynamic VID Up NB VR Dynamic VID Up V VDDNB (500mV/Div) V VDDNB (500mV/Div) I LOAD (21A/Div) SVD (2V/Div) SVT (2V/Div) I LOAD (21A/Div) SVD (2V/Div) SVT (2V/Div) VID = 1V to 1.2V, ILOAD = 20.5A Time (20μs/Div) Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 VID = 0.4V to 1V, ILOAD = 4.1A January 2014 VID = 1V to 1.4V, ILOAD = 20.5A Time (20μs/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 21 RT8877C NB VR Load Transient NB VR Load Transient V VDDNB (100mV/Div) V VDDNB (100mV/Div) I LOAD (45A/Div) I LOAD (45A/Div) fLOAD = 10kHz, ILOAD = 20A to 60A fLOAD = 10kHz, ILOAD = 60A to 20A Time (4μs/Div) Time (4μs/Div) Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 22 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Application Information Power Ready (POR) Detection During start-up, the RT8877C will detect the voltage at the voltage input pins : VCC, EN and DVD. When VCC > VCC + 4.2V DVD + 2.2V EN CMP POR + 2V CMP CMP Chip EN - higher. Current Mirror 2V + - 4.2V and VDVD > 2.2V, the IC will recognize the power state of system to be ready (POR = high) and wait for enable command at the EN pin. After POR = high and VEN >2V, the IC will enter start-up sequence for both VDD rail and VDDNB rail. If the voltage at any voltage input pin drops below low threshold (POR = low), the IC will enter power down sequence and all the functions will be disabled. Normally, connecting system power to the EN pin and power stage VIN (12V, through a voltage divider) to the DVD pin is recommended. The SVID will be ready in 2ms (max) after the chip has been enabled. All the protection latches (OVP, OCP, UVP) will be cleared only after POR = low. The condition of VEN = low will not clear these latches. While VDD and VDDNB regulate, DVD falls lower than 1.5V. Then IC will shut down immediately until POR recycle. accuracy, etc. In other words, the IBIAS pin can only be connected with a 100kΩ resistor to GND. The resistance accuracy of this resistor is recommended to be 1% or + - IBIAS 100k Figure 2. IBIAS Setting Boot VID When EN goes high, both VDD and VDDNB output begin to soft-start to the boot VID in CCM. Table 6 shows the Boot VID setting. The Boot VID is determined by the SVC and SVD input states at EN rising edge and it is stored in the internal register. The digital soft-start circuit ramps up the reference voltage at a controlled slew rate to reduce inrush current during start up. When all the output voltages are above power good threshold (300mV below Boot VID) at the end of soft-start, the controller asserts power good after a time delay. Figure 1. Power Ready (POR) Detection Table 6. 2-Bit Boot VID Code Initial Startup VID (Boot VID) Precise Reference Current Generation The RT8877C includes complicated analog circuits inside the controller. The IC needs very precise reference voltage/ current to drive these analog circuits. The IC will auto generate a 2V voltage source at IBIAS pin, and a 100kΩ resistor is required to be connected between IBIAS and analog ground, as shown in Figure 2. Through this connection, the IC will generate a 20μA current from the IBIAS pin to analog ground, and this 20μA current will be mirrored for internal use. Note that other type of connection or other values of resistance applied at the IBIAS pin may cause functional failure, such as slew rate control, OFS Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 SVC SVD VDD/VDDNB Output Voltage (V) 0 0 1.1 0 1 1.0 1 0 0.9 1 1 0.8 Start-Up Sequence After EN goes high, the RT8877C starts up and operates according to the initial settings. Figure 3 shows the simplified sequence timing diagram. The detailed operation is described in the following. is a registered trademark of Richtek Technology Corporation. www.richtek.com 23 RT8877C T0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 VCC SVID Send Byte SVC SVID Send Byte SVD VOTF Complete VOTF Complete SVT EN PWROK CCM VVDD/ Boot VID CCM VID CCM Boot VID CCM CCM VID CCM CCM VVDDNB PGOOD/ PGOODA Figure 3. Simplified Sequence Timing Diagram Description of Figure 3 : T0 : The RT8877C waits for VCC POR. T1 : The SVC pin and SVD pin set the Boot VID. Boot VID is latched at EN rising edge. SVT is driven high by the RT8877C. T2 : The enable signal goes high and all output voltages ramp up to the Boot VID in CCM. The soft-start slew rate is 3mV/μs. T3 : All output voltages are within the regulation limits and the PGOOD and PGOODA signal goes high. T4 : The PWROK pin goes high and the SVI2 interface starts running. The RT8877C waits for SVID command from processor. T5 : A valid SVID command transaction occurs between the processor and the RT8877C. T7 : The PWROK pin goes low and the SVI2 interface stops running. All output voltages go back to the boot VID in CCM. T8 : The PWROK pin goes high again and the SVI2 interface starts running. The RT8877C waits for SVID command from processor. T9 : A valid SVID command transaction occurs between the processor and the RT8877C. T10 : The RT8877C starts VID-on-the-fly transition according to the received SVID command and send a VOTF Complete if the VID reaches target VID. T11 : The enable signal goes low and all output voltages enter soft-shutdown mode. T6 : The RT8877C starts VOTF (VID-on-the-fly) transition according to the received SVID command and send a VOTF Complete if the VID reaches target VID. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 24 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Power Down Sequence SVI2 Wire Protocol If the voltage at EN pin falls below the enable falling threshold, the controller is disabled. The voltage at the PGOOD and PGOODA pin will immediately go low at the loss of enable signal at the EN pin and the controller executes soft-shutdown operation. The internal digital circuit ramps down the reference voltage at the same slew rate as that of in soft-start, making VDD and VDDNB output voltages gradually decrease in CCM. Each of the controller channels stops switching when the voltage at the voltage sense pin VSEN/VSENA, cross about 0.2V. The Boot VID information stored in the internal register is cleared at POR. This event forces the RT8877C to check the SVC and SVD inputs for a new boot VID when the EN voltage goes high again. The RT8877C complies with AMD's Voltage Regulator Specification, which defines the Serial VID Interface 2 (SVI2) protocol. With SVI2 protocol, the processor directly controls the reference voltage level of each individual controller channel and determines which controller operates in power saving mode. The SVI2 interface is a three wire bus that connects a single master to one or above slaves. The master initiates and terminates SVI2 transactions and drives the clock, SVC, and the data, SVD, during a transaction. The slave drives the telemetry, SVT during a transaction. The AMD processor is always the master. The voltage regulator controller (RT8877C) is always the slave. The RT8877C receives the SVID code and acts accordingly. The SVI protocol supports 20MHz high speed mode I2C, which is based on SVD data packet. Table 7 shows the SVD data packet. A SVD packet consists of a “Start” signal, three data bytes after each byte, and a “Stop” signal. The 8-bit serial VID codes are listed in Table1. After the RT8877C has received the stop sequence, it decodes the received serial VID code and executes the command. The controller has the ability to sample and report voltage and current for the VDD and VDDNB domains. The controller reports this telemetry serially over the SVT wire which is clocked by the processor driven SVC. A bit TFN at SVD packet along with the VDD and VDDNB domain selector bits are used by the processor to change the telemetry functionality. The telemetry bit definition is listed in Figure 4. The detailed SVI2 specification is outlined in the AMD Voltage Regulator and Voltage Regulator Module (VRM) and Serial VID Interface 2.0 (SVI2) Specification. PGOOD and PGOODA The PGOOD and PGOODA are open-drain logic outputs. The 2 pins provide the power good signal when VDD and VDDNB output voltage are within the regulation limits and no protection is triggered. These pins are typically tied to 3.3V or 5V power source through a pull-high resistor. During shutdown state (EN = low) and the soft-start period, the PGOOD and PGOODA voltages are pulled low. After a successful soft-start and VDD and VDDNB output voltages are within the regulation limits, the PGOOD and PGOODA are released high individually. The voltages at the PGOOD pin and PGOODA pin are pulled low individually during normal operation when any of the following events occurs: over voltage protection, under voltage protection, over current protection, and logic low EN voltage. If one rail triggers protection, another rail's PGOOD will be pull low after 5μs delay. Table 7. SVD Data Packet Bit Time Description 1:5 8 Always 11000b VDD domain selector bit, if set then the following two data bytes contain the VID for VDD, the PSI state for VDD, and the load line slope trim and offset trim state for VDD. VDDNB domain selector bit, if set then the following two data bytes contain the VID for VDDNB, the PSI state for VDDNB, and the load line slope trim and offset trim state for VDDNB. Always 0b 10 PSI0_L 6 7 11 : 17 19 VID Code bits [7:1] VID Code bit [0] Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 25 RT8877C Bit Time Description 20 PSI1_L 21 TFN (Telemetry Functionality) 22 : 24 Load Line Slope Trim [2:0] 25 : 26 Offset Trim [1:0] Voltage and Current Mode Selection Bit Time…… START 1 2 3 VDDNB Voltage Bit in Voltage Only Mode; Current Bit in Voltage and Current Mode VDD Voltage Bits 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 STOP SVC SVT Figure 4. Telemetry Bit Definition PWROK and SVI2 Operation VID-on-the-Fly Transition The PWROK pin is an input pin, which is connected to the global power good signal from the platform. Logic high at this pin enables the SVI2 interface, allowing data transaction between processor and the RT8877C. Once the RT8877C receives a valid SVID code, it decodes the information from processor to determine which output plane is going to move to the target VID. The internal DAC then steps the reference voltage in a controlled slew rate, making the output voltage shift to the required new VID. Depending on the SVID code, more than one controller channels can be targeted simultaneously in the VID transition. For example, VDD and VDDNB voltages can ramp up/down at the same time. After the RT8877C has received a valid SVID code, it enters CCM mode and executes the VID-on-the-fly transition by stepping up/down the reference voltage of the required controller channel(s) in a controlled slew rate, hence allowing the output voltage(s) to ramp up/down to the target VID. The output voltage slew rate during the VID-on-thefly transition is faster than that in a soft-start/soft-shutdown operation. If the new VID level is higher than the current VID level, the controller begins stepping up the reference voltage with a typical slew rate of 12.5mV/μs upward to the target VID level. If the new level is lower than the current VID level, the controller begins stepping down the reference voltage with a typical slew rate of −12.5mV/μs downward to the target VID level. If the PWROK input goes low during normal operation, the SVI2 protocol stops running. The RT8877C immediately drives SVT high and modifies all output voltages back to the boot VID, which is stored in the internal register right after the controller is enabled. The controller does not read SVD and SVC inputs after the loss of PWROK. If the PWROK input goes high again, the SVI2 protocol resumes running. The RT8877C then waits to decode the SVID command from processor for a new VID and acts as previously described. The SVI2 protocol is only running when the PWROK input goes high after the voltage at the EN pin goes high; otherwise, the RT8877C will not soft-start due to incorrect signal sequence. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 26 During the VID-on-the-fly transition, the RT8877C will force the controller channel to operate in CCM mode. If the controller channel operates in the power-saving mode prior to the VID-on-the-fly transition, it will be in CCM mode during the transition and then back to the power saving mode at the end of the transition. The voltage at the PGOOD pin and PGOODA pin will keep high during the VID-on-the-fly transition. The RT8877C checks the output voltage for voltage-related protections and send a VOTF complete at the end of VID-on-the-fly transition. In the event of receiving a VID off code, the RT8877C steps the reference voltage of required controller channel down to zero, hence making the required output voltage decrease to zero. The voltage at the PGOOD pin and PGOODA pin will remain high since the VID code is valid. is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Operation Mode Transition SET1 and SET2 Pin Setting The RT8877C supports operation mode transition function in VDD and VDDNB controller for the PSI[x]_L and command from AMD processor. Referring to Table 7, the PSI[x]_L bit in the SVI2 protocol controls the operating mode of the RT8877C controller channels. The default operation mode of VDD and VDDNB controller is CCM. When the VDD controller is in full-phase configuration and receives PSI0_L = 0 and PSI1_L = 1, the VDD controller will keep full-phase operation. When the VDD controller receives PSI0_L = 0 and PSI1_L = 0, the VDD controller takes phase shedding operation and enters diode emulation mode. In reverse, the VDD controller goes back to full-phase operation in CCM upon receiving PSI0_L = 1 and PSI1_L = 0 or 1, or PSI0_L = 0 and PSI1_L = 1. When the VDDNB controller receives PSI0_L = 0 and PSI1_L = 1, it enters single-phase CCM, when the VDDNB controller receives PSI0_L = 0 and PSI1_L = 0, it enters single-phase diode emulation mode. When the VDDNB controller goes back to full-phase CCM operation after receiving PSI0_L = 1 and PSI1_L = 0 or 1. The RT8877C provides SET1 pin for platform users to set the VDD and VDDNB controller OCP_TDC threshold and internal ramp amplitude (RSET & RSETA), SET2 pin to set VDD and VDDNB controller OCP trigger delay (OCPTRGDELAY) and quick response threshold (QRTH & QRTHA). To set these pin, platform designers should use resistive voltage divider on these pins, refer to Figure 6 and Figure 7. The voltage at SET1 and SET2 pin is VSET1 40A ROCPTDC,U ROCPTDC,D ROCPTDC,U ROCPTDC,D (3) Differential Remote Sense Setting VSET2 40A RQRTH,U RQRTH,D RQRTH,U RQRTH,D (4) The VDD and VDDNB controllers have differential, remotesense inputs to eliminate the effects of voltage drops along the PC board traces, processor internal power routes and socket contacts. The processor contains on-die sense pins, VDD_SENSE, VDDNB_SENSE and VSS_SENSE. Connect RGND to VSS_SENSE. For VDD controller, connect FB to VDD_SENSE with a resistor to build the negative input path of the error amplifier. Connect FB_NB to VDDNB_SENSE with a resistor using the same way in VDD controller. Connect VSS_SENSE to RGND using separate trace as shown in Figure 5. The precision reference voltages refer to RGND for accurate remote sensing. Processor VDD_SENSE VDDNB_SENSE VDD Controller FB FB_NB RGND RGND_NB VSET1 VCC ROCPTDC,D ROCPTDC,U ROCPTDC,D (1) VSET2 VCC RQRTH,D RQRTH,U RQRTH,D (2) The ADC monitors and decodes the voltage at this pin only once after power up. After ADC decoding (only once), a 40μA current (when VCC = 5V) will be generated at the SET1 and SET2 pin for internal use. That is the voltage at SET1 and SET2 pin is From equation (1) to equation (4) and Table 2 to Table 5, platform users can set the OCP_TDC threshold, OCP trigger delay, internal ramp amplitude and quick response threshold for VDD and VDDNB controller. RSET = VOCPTDC,DIV OCPTDC = VOCPTDC,DIV 40µA (VCC = 5V) VCC ADC 2.24V VOCPTDC,DIV VOCPTDC,DIV VOCPTDC Register VOCPTDC,2 ROCPTDC,U SET1 ROCPTDC,D RT8877C Figure 6. OCP_TDC/RSET Setting VDD NB Controller VSS_SENSE Figure 5. Differential Remote Voltage Sense Connection Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 27 RT8877C OCPTRGDELAY = VQRTH,DIV QRTH = VQRTH,DIV AVP. A near-DC offset canceling is added to the output of EA to eliminate the inherent output offset of finite gain peak current mode controller. 40µA (VCC = 5V) VIN VCC VQRTH,DIV VQRTH Register VQRTH,2 SET2 CCRCOT PWM Logic RQRTH,U RQRTH,D RT8877C Figure 7. QRTH/OCPTRGDELAY Setting + CMP - VQRTH,DIV 2.24V COMP2 ADC 0.4 x1 VCS + - Loop Control The VDD controller adopts Richtek's proprietary G-NAVPTM topology. G-NAVPTM is based on the finite gain peak current mode with CCRCOT (Constant Current Ripple Constant On-Time) topology. The output voltage, VVDD will decrease with increasing output load current. The control loop consists of PWM modulators with power stages, current sense amplifiers and an error amplifier as shown in Figure 8. Similar to the peak current mode control with finite compensator gain, the HS_FET on-time is determined by CCRCOT on-time generator. When load current increases, VCS increases, the steady state COMP voltage also increases and induces VVDD to decrease, thus achieving Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 28 RX EA + CX RC C ISENxP ISENxN RCSx RIMON IMON + PWM controller. Pulling ISEN4N to VCC programs a 3phase operation, pulling ISEN3N to VCC programs a 2phase operation, and pulling ISEN2N to VCC programs a 1-phase operation. At EN rising edge, VDD controller detects whether the voltages of ISEN2N, ISEN3N and ISEN4N are higher than “VCC − 0.5V” respectively to decide how many phases should be active. Phase selection is only active during POR. When POR = high, the number of active phases is determined and latched. The unused ISENxP pins are recommended to be connected to VCC and unused PWM pins can be left floating. Driver VREF VDD Controller The number of active phases is determined by the internal circuitry that monitors the ISENxN voltages during startup. Normally, the VDD controller operates as a 4-phase HS_FET VVDD L RSENSE LS_FET Offset Canceling Active Phase Determination : Before POR PWMx C1 C2 R2 COMP FB RGND R1 VVDD_SENSE VSS_SENSE VDAC,VDD Figure 8. VDD Controller : Simplified Schematic for Droop and Remote Sense in CCM Droop Setting It's very easy to achieve Active Voltage Positioning (AVP) by properly setting the error amplifier gain due to the native droop characteristics as shown in Figure 9. This target is to have VVDD = VDAC, VDD − ILOAD x RDROOP (5) Then solving the switching condition VCOMP2 = VCS in Figure 8 yields the desired error amplifier gain as GI (6) A V R2 R1 RDROOP GI RSENSE RIMON 4 RCSx 10 (7) where GI is the internal current sense amplifier gain. RSENSE is the current sense resistor. If no external sense resistor present, it is the equivalent resistance of the inductor. RDROOP is the equivalent load line resistance as well as the desired static output impedance. VVDD AV2 > AV1 AV2 AV1 0 Load Current Figure 9. VDD Controller : Error Amplifier gain (AV) Influence on VVDD Accuracy is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Loop Compensation Optimized compensation of the VDD controller allows for best possible load step response of the regulator's output. A type-I compensator with one pole and one zero is adequate for proper compensation. Figure 10 shows the compensation circuit. Previous design procedure shows how to select the resistive feedback components for the error amplifier gain. Next, C1 and C2 must be calculated for compensation. The target is to achieve constant resistive output impedance over the widest possible frequency range. The pole frequency of the compensator must be set to compensate the output capacitor ESR zero : fP 1 2 C RC (8) Where C is the capacitance of output capacitor, and RC is the ESR of output capacitor. C2 can be calculated as follows : C x RC (9) C2 R2 The zero of compensator has to be placed at half of the switching frequency to filter the switching related noise. Such that, 1 C1 (10) R1 fSW COMP C1 R2 R1 FB + EA + C2 RGND VVDD_SENSE VSS_SENSE VDAC Figure 10. VDD Controller : Compensation Circuit TON Setting High frequency operation optimizes the application for the smaller component size, trading off efficiency due to higher switching losses. This may be acceptable in ultra portable devices where the load currents are lower and the controller is powered from a lower voltage supply. Low frequency operation offers the best overall efficiency at the expense of component size and board space. Figure 11 shows the On-Time setting Circuit. Connect a resistor (RTON) between VIN and TONSET to set the on-time of UGATE : Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 12 24.4 10 RTON (11) VIN VDAC where tON is the UGATE turn on period, VIN is Input voltage of the VDD controller, and VDAC is the DAC voltage. tON (0.5V VDAC 1.8V) When VDAC is larger than 1.8V, the equivalent switching frequency may be over 500kHz, and this too fast switching frequency is unacceptable. Therefore, the VDD controller implements a pseudo constant frequency technology to avoid this disadvantage of CCRCOT topology. When VDAC is larger than 1.8V, the on-time equation will be modified to : 12 13.55 10 RTON VDAC (12) tON (VDAC 1.8V) VIN VDAC On-time translates only roughly to switching frequencies. The on-times guaranteed in the Electrical Characteristics are influenced by switching delays in external HS-FET. Also, the dead-time effect increases the effective on-time, which in turn reduces the switching frequency. It occurs only in CCM and during dynamic output voltage transitions. When the inductor current reverses at light or negative load currents, with reversed inductor current, the phase goes high earlier than normal, extending the on-time by a period equal to the HS-FET rising dead time. For better efficiency of the given load range, the maximum switching frequency is suggested to be : 1 fS(MAX) (kHz) x TON THSDelay VDAC(MAX) ILOAD(MAX) x RON _ LS FET DCRL RDROOP VIN(MAX) ILOAD(MAX) x RON _ LSFET RON _ HSFET (13) Where fS(MAX) is the maximum switching frequency, tHSDELAY is the turn-on delay of HS-FET, VDAC(MAX) is the Maximum VDAC of application, VIN(MAX) is the Maximum application Input voltage, ILOAD(MAX) is the maximum load of application, RON_LS-FET is the Low side FET RDS(ON), RON_HS-FET is the High side FET RDS(ON) , DCRL is the equivalent resistance of the inductor, and RDROOP is the load line setting. CCRCOT On-Time Computer TONSET VDAC RTON R1 VIN C1 On-Time Figure 11. VDD Controller : On-Time Setting with RC filter is a registered trademark of Richtek Technology Corporation. www.richtek.com 29 RT8877C Current Sense Setting Per-Phase Over Current Protection The current sense topology of the VDD controller is continuous inductor current sensing. Therefore, the controller has less noise sensitive. Low offset amplifiers are used for current balance, loop control and over current detection. The ISENxP and ISENxN pins denote the positive and negative input of the current sense amplifier of each phase. The VDD controller provides over current protection in each phase. For VDD controller in four-phase configuration, either phase can trigger Per-Phase Over Current Protection (PHOCP). Users can either use a current sense resistor or the inductor's DCRL for current sensing. Using the inductor's DCRL allows higher efficiency as shown in Figure 12. IL L RX ISENxN + - 10µA Current Mirror ISENAxN DCRL CX RCSx Figure 12. VDD Controller : Lossless Inductor Sensing In order to optimize transient performance, RX and CX must be set according to the equation below : L R C (14) X X DCRL Then the proportion between the phase current, IL, and the sensed current, ISENxN, is driven by the value of the effective sense resistance, RCSx, and the DCRL of the inductor. The resistance value of RCSx is limited by the internal circuitry. The recommended value is from 500Ω to 1.2kΩ. DCRL (15) ISENxN IL RCSx Considering the inductance tolerance, the resistor RX has to be tuned on board by examining the transient voltage. If the output voltage transient has an initial dip below the minimum load line requirement and the recovery is too fast causing a ring back. Vice versa, with a resistance too large the output voltage transient has only a small initial dip with a slow recovery. Using current sense resistor in series with the inductor can have better accuracy, but the efficiency is a trade-off. Considering the equivalent inductance (LESL) of the current sense resistor, an RC filter is recommended. The RC filter calculation method is similar to the above mentioned inductor equivalent resistance sensing method. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 30 1 I 8 SENAxN PHOCP trigger VVDD ISENxP ISENxN The VDD controller senses each phase inductor current IL, and PHOCP comparator compares sensed current with PHOCP threshold current, as shown in Figure 13. Figure 13. VDD Controller : Per-Phase OCP Setting The resistor RCSx determines PHOCP threshold. DCRL 1 = 10A RCSx 8 IL,PERPHASE(MAX) DCRL RCSx 8 10A (16) IL,PERPHASE(MAX) (17) The controller will turn off all high side/low side MOSFETs to protect CPU if the per-phase over current protection is triggered. Current Balance The VDD controller implements internal current balance mechanism in the current loop. The VDD controller senses and compares per-phase current signal with average current. If the sensed current of any particular phase is larger than average current, the on-time of this phase will be adjusted to be shorter. Initial Offset and External Offset (Over Clocking Offset Function) The VDD controller features over clocking offset function which provides the possibility of wide range off set of output voltage. The initial offset function can be implemented through the SVI interface. When the OFS pin voltage < 0.3V at EN rising edge, the initial offset is disabled. The external offset function can be implemented by SET2 pin setting. For example, referring to Table 8, when the both rail external offset functions are enabled, the output voltage is : is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C VVDD VDAC ILOAD x RDROOP + VExternal _ OFS + VInitial _ OFS Current Monitoring and Current Reporting (18) VInitial_OFS is the initial offset voltage set by SVI interface, and the external offset voltage, VExternal_OFS is set by supplying a voltage into OFS pin. It can be calculated as below : VExternal _ OFS = VOFS 1.2V (19) If supplying 1.3V at OFS pin , it will achieve 100mV offset at the output. Connecting a filter capacitor between the OFS pin and GND is necessary. Designers can design the offset slew rate by properly setting the filter bandwidth. Table 8. External Offset Function Setting for VDD and VDDNB Controller Core_ NB_ OFFSET_ OFFSET_ Description EN EN 0 0 Disable external offset function. NB rail external offset is set by 0 1 OFS pin voltage. 1 1 0 Core rail external offset is set by OFSA pin voltage. 1 Core rail external offset is set by OFS pin voltage, and NB rail external offset is set by OFSA pin voltage. Dynamic VID Enhancement DCRL VIMON = IL,SUM RIMON 0.64 RCSx (20) Where IL is the phase current, RCSx is the effective sense resistance, and RIMON is the current monitor current setting resistor. Note that the IMON pin cannot be monitored. The ADC circuit of the VDD controller monitors the voltage variation at the IMON pin from 0V to 3.19375V, and this voltage is decoded into digital format and stored into Output_Current register. The ADC divides 3.19375V into 511 levels, so LSB = 3.19375V / 511 = 6.25mV. Quick Response The VDD controller utilizes a quick response feature to support heavy load current demand during instantaneous load transient. The VDD controller monitors the current of the VVDD_SENSE, and this current is mirrored to internal quick response circuit. At steady state, this mirrored current will not trigger a quick response. When the VVDD_SENSE voltage drops abruptly due to load apply transient, the mirrored current flowing into quick response circuit will also increase instantaneously. The QR threshold setting for VDD controller refers to Table 4. QRTH QR Pulse Generation Circuit + CMP - + During a dynamic VID event, the charging (dynamic VID up) or discharging (dynamic VID down) current causes unwanted load-line effect which degrades the settling time performance. The RT8877C will hold the inductor current to hold the load-line during a dynamic VID event. The VDD controller will always enter four-phase configuration when VDD controller receives dynamic VID up and VDD controller will hold the operating state when VDD controller receives dynamic VID down. The VDD controller provides current monitoring function via inductor current sensing. In G-NAVPTM technology, the output voltage is dependent on output current, and the current monitoring function is achieved by this characteristic of output voltage. The equivalent output current will be sensed from inductor current sensing and mirrored to IMON pin. The resistor connected to IMON pin determines voltage of the IMON output. VVDD_SENSE Ramp Amplitude Adjust When the VDD controller takes phase shedding operation and enters diode emulation mode, the internal ramp of VDD controller will be modified for the reason of stability. In case of smooth transition into DEM, the CCM ramp amplitude should be designed properly. The RT8877C provides SET1 pin for platform users to set the ramp amplitude of the VDD controller in CCM. Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 Figure 14. VDD Controller : Quick Response Triggering Circuit When quick response is triggered, the quick response circuit will generate a quick response pulse. The pulse width of quick response is almost the same with tON. is a registered trademark of Richtek Technology Corporation. www.richtek.com 31 RT8877C After generating a quick response pulse, the pulse is then applied to the on-time generating circuit, and all the active phases' on-time will be overridden by the quick response pulse. Over Current Protection The RT8877C has dual OCP mechanism. The dual OCP mechanism has two types of thresholds. The first type, referred to as OCP-TDC, is a time and current based threshold. OCP-TDC should trip when the average output current exceeds TDC by some percentage and for a period of time. This period of time is referred to as the trigger delay. The second type, referred to as OCP-SPIKE, is a current based threshold. OCP-SPIKE should trip when the cycle-by-cycle output current exceeds IDDSPIKE by some percentage. If either mechanism trips, then the VDD controller asserts OCP_L and delays any further action. This delay is called an action delay. Refer to action delay time. After the action delay has expired and the VDD controller has allowed its current sense filter to settle out and the current has not decreased below the threshold, then the VDD controller will turn off both high side MOSFETs and low side MOSFETs of all channels. Users can set OCP-SPIKE threshold, IL,SUM (SPIKE), by the current monitor resistor RIMON of the following equation : R IL,SUM (SPIKE) = 3.19375 0.64 CSx (21) DCRL RIMON And set the OCP-TDC threshold, IL(TDC), refer to some percentage of OCP-SPIKE through Table 2. Over Voltage Protection (OVP) The over voltage protection circuit of the VDD controller monitors the output voltage via the VSEN pin after POR. When VID is lower than 0.9V, once VSEN exceeds “0.9V + 325mV”, OVP is triggered and latched. When VID is larger than 0.9V, once VSEN exceeds the internal reference by 325mV, OVP is triggered and latched. The VDD controller will try to turn on low side MOSFETs and turn off high side MOSFETs of all active phases of the VDD controller to protect the CPU. When OVP is triggered by one rail, the other rail will also enter soft shut down sequence. A 1μs delay is used in OVP detection circuit to prevent false trigger. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 32 Negative Voltage Protection (NVP) During OVP latch state, the VDD controller also monitors the VSEN pin for negative voltage protection. Since the OVP latch continuously turns on all low side MOSFETs of the VDD controller, the VDD controller may suffer negative output voltage. As a consequence, when the VSEN voltage drops below 0V after triggering OVP, the VDD controller will trigger NVP to turn off all low side MOSFETs of the VDD controller while the high side MOSFETs remains off. After triggering NVP, if the output voltage rises above 0V, the OVP latch will restart to turn on all low side MOSFETs. The NVP function will be active only after OVP is triggered. Under Voltage Protection (UVP) The VDD controller implements under voltage protection of VOUT,VDD. If VSEN is less than the internal reference by 325mV, the VDD controller will trigger UVP latch. The UVP latch will turn off both high side and low side MOSFETs. When UVP is triggered by one rail, the other rail will also enter soft shut down sequence. A 3μs delay is used in UVP detection circuit to prevent false trigger. Under Voltage Lock Out (UVLO) During normal operation, if the voltage at the VCC or DVD pin drops below POR threshold, the VDD controller will trigger UVLO. The UVLO protection forces all high side MOSFETs and low side MOSFETs off by shutting down internal PWM logic drivers. A 3μs delay is used in UVLO detection circuit to prevent false trigger. VDDNB Controller VDDNB Controller Disable The VDDNB controller can be disabled by connecting ISENA1N to a voltage higher than VCC. If not in use, ISENAxP is recommended to be connected to VCC, while PWMAx is left floating. When VDDNB controller is disabled, all SVID commands related to VDDNB controller will be rejected. Loop Control The VDDNB controller adopts Richtek's proprietary GNAVPTM topology. G-NAVPTM is based on the finite gain peak current mode with CCRCOT (Constant Current Ripple is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Constant On-Time) topology. The output voltage, VVDDNB will decrease with increasing output load current. The control loop consists of PWM modulators with power stages, current sense amplifiers and an error amplifier as shown in Figure 15. Similar to the peak current mode control with finite compensator gain, the HS_FET on-time is determined by CCRCOT on-time generator. When load current increases, VCS increases, the steady state COMPA voltage also increases and induces VVDDNB to decrease, thus achieving AVP. A near-DC offset canceling is added to the output of EA to eliminate the inherent output offset of finite gain peak current mode controller. VIN COMP2 + CMP - CCRCOT PWMAx PWM Logic HS_FET VVDDNB L RSENSE Driver RX LS_FET 0.4 x2 VCS + - CX RC C ISENAxP ISENAxN RCSx IMONA RIMONA Offset Canceling VREF + COMPA FBA EA RGND + VDAC, VDDNB C2 R2 C1 R1 VVDDNB_SENSE VSS_SENSE Figure 15. VDDNB Controller : Simplified Schematic for Droop and Remote Sense in CCM Droop Setting It's very easy to achieve Active Voltage Positioning (AVP) by properly setting the error amplifier gain due to the native droop characteristics as shown in Figure 16. This target is to have VVDDNB = VDAC,VDDNB − ILOAD x RDROOP (22) Then solving the switching condition VCOMP2 = VCS in Figure 17 yields the desired error amplifier gain as GI A V R2 R1 RDROOP VVDDNB AV2 AV1 0 Loop Compensation Optimized compensation of the VDDNB controller allows for best possible load step response of the regulator’s output. A type-I compensator with one pole and one zero is adequate for proper compensation. Figure 17 shows the compensation circuit. Previous design procedure shows how to select the resistive feedback components for the error amplifier gain. Next, C1 and C2 must be calculated for compensation. The target is to achieve constant resistive output impedance over the widest possible frequency range. The pole frequency of the compensator must be set to compensate the output capacitor ESR zero : fP 1 2 C RC Where C is the capacitance of output capacitor, and RC is the ESR of output capacitor. C2 can be calculated as follows : C x RC (26) C2 R2 The zero of compensator has to be placed at half of the switching frequency to filter the switching related noise. Such that, 1 C1 (27) R1 fSW COMPA EA + C2 C1 R2 R1 FBA + January 2014 (25) (23) RSENSE (24) RIMON 8 RCSx 10 where GI is the internal current sense amplifier gain. RSENSE is the current sense resistor. If no external sense resistor present, it is the equivalent resistance of the inductor. RDROOP is the equivalent load line resistance as well as the desired static output impedance. DS8877C-01 Load Current Figure 16. VDDNB Controller : Error Amplifier gain (AV) Influence on VVDDNB Accuracy where GI Copyright © 2014 Richtek Technology Corporation. All rights reserved. AV2 > AV1 RGND VVDDNB_SENSE VSS_SENSE VDAC,VDDNB Figure 17. VDDNB Controller : Compensation Circuit is a registered trademark of Richtek Technology Corporation. www.richtek.com 33 RT8877C TON Setting High frequency operation optimizes the application for the smaller component size, trading off efficiency due to higher switching losses. This may be acceptable in ultra portable devices where the load currents are lower and the controller is powered from a lower voltage supply. Low frequency operation offers the best overall efficiency at the expense of component size and board space. Figure 18 shows the On-Time setting Circuit. Connect a resistor (RTON) between VIN and TONSETA to set the on-time of UGATE : 24.4 1012 RTON (28) tON (0.5V VDAC 1.8V) VIN VDAC,VDDNB where tON is the UGATE turn on period, VIN is Input voltage of the VDDNB controller, and VDAC,VDDNB is the DAC voltage. When VDAC,VDDNB is larger than 1.8V, the equivalent switching frequency may be over 500kHz, and this too fast switching frequency is unacceptable. Therefore, the VDDNB controller implements a pseudo constant frequency technology to avoid this disadvantage of CCRCOT topology. When VDAC,VDDNB is larger than 1.8V, the on-time equation will be modified to : tON (VDAC 1.8V) 12 13.55 10 RTON VDAC,VDDNB (29) VIN VDAC,VDDNB On-time translates only roughly to switching frequencies. The on-times guaranteed in the Electrical Characteristics are influenced by switching delays in external HS-FET. Also, the dead-time effect increases the effective on-time, which in turn reduces the switching frequency. It occurs only in CCM and during dynamic output voltage transitions When the inductor current reverses at light or negative load currents, with reversed inductor current, the phase goes high earlier than normal, extending the on-time by a period equal to the HS-FET rising dead time. For better efficiency of the given load range, the maximum switching frequency is suggested to be : fS(MAX) (kHz) 1 x TON THSDelay VDAC(MAX) ILOAD(MAX) x RON _ LSFET DCRL RDROOP VIN(MAX) ILOAD(MAX) x RON _ LSFET RON _ HSFET (30) Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 34 Where fS(MAX) is the maximum switching frequency, tHSDELAY is the turn-on delay of HS-FET, VDAC(MAX) is the Maximum V DAC,VDDNB of application, V IN(MAX) is the Maximum application Input voltage, I LOAD(MAX) is the maximum load of application, RON_LS-FET is the Low side FET RDS(ON) , RON_HS-FET is the High side FET RDS(ON) , DCRL is the equivalent resistance of the inductor, and RDROOP is the load line setting. CCRCOT On-Time Computer TONSETA RTON R1 VIN C1 VDAC,VDDNB On-Time Figure 18. VDDNB Controller : On-Time Setting with RC Filter Current Sense Setting The current sense topology of the VDDNB controller is continuous inductor current sensing. Therefore, the controller has less sensitive noise. Low offset amplifiers are used for current balance, loop control and over current detection. The ISENAxP and ISENAxN pins denote the positive and negative input of the current sense amplifier of each phase. Users can either use a current sense resistor or the inductor's DCRL for current sensing. Using the inductor's DCRL allows higher efficiency as shown in Figure 19. VVDDNB IL L RX ISENAxN + - DCRL CX ISENAxP ISENAxN RCSx Figure 19. VDDNB Controller : Lossless Inductor Sensing In order to optimize transient performance, RX and CX must be set according to the equation below : L R C (31) X X DCRL Then the proportion between the phase current, IL, and the sensed current, ISENAxN, is driven by the value of the effective sense resistance, RCSx, and the DCRL of the is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C inductor. The resistance value of RCSx is limited by the internal circuitry. The recommended value is from 500Ω to 1.2kΩ. DCRL (32) ISENAxN IL RCSx Considering the inductance tolerance, the resistor RX has to be tuned on board by examining the transient voltage. If the output voltage transient has an initial dip below the minimum load line requirement and the recovery is too fast causing a ring back. Vice versa, with a resistance too large the output voltage transient has only a small initial dip with a slow recovery. Initial Offset and External Offset (Over Clocking Offset Function) Using current sense resistor in series with the inductor can have better accuracy, but the efficiency is a trade-off. Considering the equivalent inductance (LESL) of the current sense resistor, an RC filter is recommended. The RC filter calculation method is similar to the above mentioned inductor equivalent resistance sensing method. VVDDNB VDAC,VDDNB ILOAD RDROOP The VDDNB controller features over clocking offset function which provides the possibility of wide range offset of output voltage. The initial offset function can be implemented through the SVI interface. When the OFSA pin voltage < 0.3V at EN rising edge, the initial offset is disabled. The external offset function can be implemented by SET2 pin setting. For example, referring to Table 8, when the both rail external offset functions are enabled, the output voltage is : + VExternal _ OFSA + VInitial _ OFSA (35) VInitial_OFSA is the initial offset voltage set by SVI interface, and the external offset voltage, VExternal_OFSA is set by supplying a voltage into OFSA pin. It can be calculated as below : Per-Phase Over Current Protection VExternal _ OFSA = VOFSA 1.2V The VDDNB controller provides over current protection in each phase. For VDDNB controller in two-phase configuration, either phase can trigger Per-Phase Over Current Protection (PHOCP). If supplying 1.3V at OFSA pin, it will achieve 100mV offset at the output. Connecting a filter capacitor between the OFSA pin and GND is necessary. Designers can design the offset slew rate by properly setting the filter bandwidth. The VDDNB controller senses each phase inductor current IL, and PHOCP comparator compares sensed current with PHOCP threshold current, as shown in Figure 20. Dynamic VID Enhancement Current Mirror 1 I 8 SENAxN PHOCP trigger 10µA ISENAxN (36) During a dynamic VID event, the charging (dynamic VID up) or discharging (dynamic VID down) current causes unwanted load-line effect which degrades the settling time performance. The RT8877C will hold the inductor current to hold the load-line during a dynamic VID event. The VDDNB controller will always enter two-phase configuration when VDDNB controller receives dynamic VID up and VDDNB controller will hold the operating state when VDDNB controller receives dynamic VID down. Figure 20. VDDNB Controller : Per-Phase OCP Setting Ramp Amplitude Adjust The resistor RCSx determines PHOCP threshold. DCRL 1 IL,PERPHASE(MAX) = 10A RCSx 8 When the VDDNB controller takes phase shedding (33) IL,PERPHASE(MAX) DCRL (34) 8 10A The controller will turn off all high side/low side MOSFETs to protect CPU if the per-phase over current protection is triggered. RCSx Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 operation and enters diode emulation mode, the internal ramp of VDDNB controller will be modified for the reason of stability. In case of smooth transition into DEM, the CCM ramp amplitude should be designed properly. The RT8877C provides SET1 pin for platform users to set the ramp amplitude of the VDDNB controller in CCM. is a registered trademark of Richtek Technology Corporation. www.richtek.com 35 RT8877C Current Monitoring and Current Reporting The VDDNB controller provides current monitoring function via inductor current sensing. In G-NAVPTM technology, the output voltage is dependent on output current, and the current monitoring function is achieved by this characteristic of output voltage. The equivalent output current will be sensed from inductor current sensing and mirrored to IMONA pin. The resistor connected to IMONA pin determines voltage of the IMONA output. DCRL (37) RIMONA 0.64 RCSx Where IL is the phase current, RCSx is the effective sense resistance, and RIMONA is the current monitor current setting resistor. Note that the IMONA pin cannot be monitored. VIMONA = IL,SUM 2 The ADC circuit of the VDDNB controller monitors the voltage variation at the IMONA pin from 0V to 3.19375V, and this voltage is decoded into digital format and stored into Output_Current register. The ADC divides 3.19375V into 511 levels, so LSB = 3.19375V / 511 = 6.25mV. Quick Response The VDDNB controller utilizes a quick response feature to support heavy load current demand during instantaneous load transient. The VDDNB controller monitors the current of the VVDDNB_SENSE, and this current is mirrored to internal quick response circuit. At steady state, this mirrored current will not trigger a quick response. When the VVDDNB_SENSE voltage drops abruptly due to load apply transient, the mirrored current flowing into quick response circuit will also increase instantaneously. The QR threshold setting for VDDNB controller refers to Table 5. QRTHA + CMP - + QR Pulse Generation Circuit VVDDNB_SENSE Figure 21. VDDNB Controller : Quick Response Triggering Circuit When quick response is triggered, the quick response circuit will generate a quick response pulse. The pulse width of quick response is almost the same with tON. Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 36 After generating a quick response pulse, the pulse is then applied to the on-time generation circuit, and all the active phases' on-times will be overridden by the quick response pulse. Over Current Protection The RT8877C has dual OCP mechanism. The dual OCP mechanism has two types of thresholds. The first type, referred to as OCP-TDCA, is a time and current based threshold. OCP-TDCA should trip when the average output current exceeds TDCA by some percentage and for a period of time. This period of time is referred to as the trigger delay. The second type, referred to as OCPSPIKEA, is a current based threshold. OCP-SPIKEA should trip when the cycle-by-cycle output current exceeds IDDSPIKEA by some percentage. If either mechanism trips, then the VDDNB controller asserts OCP_L and delays any further action. This delay is called an action delay. Refer to action delay time. After the action delay has expired and the VDDNB controller has allowed its current sense filter to settle out and the current has not decreased below the threshold, then the VDDNB controller will turn off both high side MOSFETs and low side MOSFETs of all channels. Users can set OCP-SPIKEA threshold, IL,SUM (SPIKEA), by the current monitor resistor R IMONA of the following equation : R IL,SUM (SPIKEA) = 3.19375 0.64 CSx (38) 2 DCRL RIMONA And set the OCP-TDCA threshold, IL(TDCA), refer to some percentage of OCP-SPIKEA through Table 3. Over Voltage Protection (OVP) The over voltage protection circuit of the VDDNB controller monitors the output voltage via the VSENA pin after POR. When VID is lower than 0.9V, once VSENA exceeds “0.9V + 325mV”, OVP is triggered and latched. When VID is larger than 0.9V, once V SENA exceeds the internal reference by 325mV, OVP is triggered and latched. The VDDNB controller will try to turn on low side MOSFETs and turn off high side MOSFETs of all active phases of the VDDNB controller to protect the CPU. When OVP is triggered by one rail, the other rail will also enter soft shut down sequence. A 1μs delay is used in OVP detection circuit to prevent false trigger. is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C During OVP latch state, the VDDNB controller also monitors the VSENA pin for negative voltage protection. Since the OVP latch continuously turns on all low side MOSFETs of the VDDNB controller, the VDDNB controller may suffer negative output voltage. As a consequence, when the VSENA voltage drops below 0V after triggering OVP, the VDDNB controller will trigger NVP to turn off all low side MOSFETs of the VDDNB controller while the high side MOSFETs remains off. After triggering NVP, if the output voltage rises above 0V, the OVP latch will restart to turn on all low side MOSFETs. The NVP function will be active only after OVP is triggered. Under Voltage Protection (UVP) The VDDNB controller implements under voltage protection of VOUT,VDDNB. If VSENA is less than the internal reference by 325mV, the VDDNB controller will trigger UVP latch. The UVP latch will turn off both high side and low side MOSFETs. When UVP is triggered by one rail, the other rail will also enter soft shut down sequence. A 3μs delay is used in UVP detection circuit to prevent false trigger. Under Voltage Lock Out (UVLO) During normal operation, if the voltage at the VCC or DVD pin drops below POR threshold, the VDDNB controller will trigger UVLO. The UVLO protection forces all high side MOSFETs and low side MOSFETs off by shutting down internal PWM logic drivers. A 3μs delay is used in UVLO detection circuit to prevent false trigger. For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For WQFN-52L 6x6 package, the thermal resistance, θJA, is 26.5°C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : PD(MAX) = (125°C − 25°C) / (26.5°C/W) = 3.77W for WQFN-52L 6x6 package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 22 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. 4.0 Maximum Power Dissipation (W)1 Negative Voltage Protection (NVP) Four-Layer PCB 3.6 3.2 2.8 2.4 2.0 1.6 1.2 0.8 0.4 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 22. Derating Curve of Maximum Power Dissipation Thermal Considerations For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : PD(MAX) = (TJ(MAX) − TA) / θJA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8877C-01 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 37 RT8877C Outline Dimension 1 1 2 2 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Symbol Dimensions In Millimeters Dimensions In Inches Min. Max. Min. Max. A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.150 0.250 0.006 0.010 D 5.950 6.050 0.234 0.238 D2 4.650 4.750 0.183 0.187 E 5.950 6.050 0.234 0.238 E2 4.650 4.750 0.183 0.187 e 0.400 0.016 L 0.350 0.450 0.014 0.018 L1 0.300 0.400 0.012 0.016 W-Type 52L QFN 6x6 Package Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 38 is a registered trademark of Richtek Technology Corporation. DS8877C-01 January 2014 RT8877C Richtek Technology Corporation 14F, No. 8, Tai Yuen 1st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. DS8877C-01 January 2014 www.richtek.com 39