Cool-Power® PI33XX-X1 8V to 36Vin, 15A Cool-Power ZVS Buck Regulator Family Description Features The PI33XX is a family of high efficiency, wide input range DC-DC ZVS-Buck regulators integrating controller, power switches, and support components all within a high density System-in-Package (SiP). The integration of a high performance Zero-Voltage Switching (ZVS) topology, within the PI33XX series, increases point of load performance providing best in class power efficiency. The PI33XX requires only an external inductor and minimal capacitors to form a complete DC-DC switching mode buck regulator. Output Voltage Device Iout Max Set Range PI3311-X1-LGIZ 1.0V 1.0 to 1.4V 15A PI3318-X1-LGIZ 1.8V 1.4 to 2.0V 15A PI3312-X1-LGIZ 2.5V 2.0 to 3.1V 15A PI3301-X1-LGIZ 3.3V 2.3 to 4.1V 15A Table 1 - PI33XX-X1 Portfolio. The ZVS architecture also enables high frequency operation while minimizing switching losses and maximizing efficiency. The high switching frequency operation reduces the size of the external filtering components, improves power density, and enables very fast dynamic response to line and load transients. The PI33XX series sustains high switching frequency all the way up to the rated input voltage without sacrificing efficiency and, with its 20ns minimum on-time, supports large step down conversions up to 36Vin. High Efficiency ZVS-Buck Topology Wide input voltage range of 8V to 36V Very-Fast transient response High accuracy pre-trimmed output voltage User adjustable soft-start & tracking Power-up into pre-biased load (select versions) Parallel capable with single wire current sharing Input Over/Under Voltage Lockout (OVLO/UVLO) Output Overvoltage Protection (OVP) Over Temperature Protection (OTP) Fast and slow current limits -40°C to 125°C operating range (TJ) 2 Optional I C functionality & programmability: Vout margining Fault reporting Enable and SYNCI pin polarity Phase delay (interleaving multiple regulators) Applications High efficiency systems Computing, Communications, Industrial, Automotive Equipment High voltage battery operation Package Information 10mm x 14mm x 2.6mm LGA SiP I2C is a trademark of NXP Semiconductors vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 1 of 26 PI33XX-X1 Contents Order Information ...................................................... 3 Application Description .............................................21 Pin Description............................................................ 4 Output Voltage Trim ............................................ 21 Package Pin-Out.......................................................... 4 Soft-Start Adjust and Tracking ............................. 22 Absolute Maximum Ratings ........................................ 5 Inductor Pairing ................................................... 22 PI3311-X1 (1.0 Vout) Electrical Characteristics........... 6 Layout Guidelines ......................................................23 PI3318-X1 (1.8 Vout) Electrical Characteristics........... 9 Recommended PCB Footprint and Stencil ................24 PI3312-X1 (2.5 Vout) Electrical Characteristics......... 12 Package Drawings .....................................................25 PI3301-X1 (3.3 Vout) Electrical Characteristics......... 15 Warranty ...................................................................26 Functional Description .............................................. 18 ENABLE (EN) .........................................................18 Switching Frequency Synchronization..................18 Output Voltage Trim.............................................18 Soft-Start ..............................................................18 Remote Sensing ....................................................18 Output Current Limit Protection ..........................19 Input Under-Voltage Lockout ...............................19 Input Over Voltage Lockout .................................19 Output Over Voltage Protection ..........................19 Over Temperature Protection ..............................19 Pulse Skip Mode (PSM) ........................................19 Variable Frequency Operation .............................20 Parallel Operation ................................................20 2 I C Interface Operation ....................................... 20 vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 2 of 26 PI33XX-X1 Order Information Output Range Set Range Iout Max PI3311-01-LGIZ 1.0V 1.0 to 1.4V 15A 10mm x 14mm 123-pin LGA TRAY PI3318-01-LGIZ 1.8V 1.4 to 2.0V 15A 10mm x 14mm 123-pin LGA TRAY PI3312-01-LGIZ 2.5V 2.0 to 3.1V 15A 10mm x 14mm 123-pin LGA TRAY PI3301-01-LGIZ 3.3V 2.3 to 4.1V 15A 10mm x 14mm 123-pin LGA TRAY Cool-Power Package Transport Media Lower Current Versions (Refer to PI33XX-X0-LGIZ Datasheet) PI3311-00-LGIZ 1.0V 1.0 to 1.4V 10A 10mm x 14mm 123-pin LGA TRAY PI3318-00-LGIZ 1.8V 1.4 to 2.0V 10A 10mm x 14mm 123-pin LGA TRAY PI3312-00-LGIZ 2.5V 2.0V to 3.1V 10A 10mm x 14mm 123-pin LGA TRAY PI3301-00-LGIZ 3.3V 2.3 to 4.1V 10A 10mm x 14mm 123-pin LGA TRAY PI3302-00-LGIZ 5.0V 3.3 to 6.5V 10A 10mm x 14mm 123-pin LGA TRAY PI3303-00-LGIZ 12V 6.5 to 13.0V 8A 10mm x 14mm 123-pin LGA TRAY PI3305-00-LGIZ 15V 10.0 to 16.0V 8A 10mm x 14mm 123-pin LGA TRAY I2C Functionality & Programmability PI3311-21-LGIZ 1.0V 1.0 to 1.4V 15A 10mm x 14mm 123-pin LGA TRAY PI3318-21-LGIZ 1.8V 1.4 to 2.0V 15A 10mm x 14mm 123-pin LGA TRAY PI3312-21-LGIZ 2.5V 2.0 to 3.1V 15A 10mm x 14mm 123-pin LGA TRAY PI3301-21-LGIZ 3.3V 2.3 to 4.1V 15A 10mm x 14mm 123-pin LGA TRAY PI3311-20-LGIZ 1.0V 1.0 to 1.4V 10A 10mm x 14mm 123-pin LGA TRAY PI3318-20-LGIZ 1.8V 1.0 to 1.4V 10A 10mm x 14mm 123-pin LGA TRAY PI3312-20-LGIZ 2.5V 2.0 to 3.1V 10A 10mm x 14mm 123-pin LGA TRAY PI3301-20-LGIZ 3.3V 2.3 to 4.1V 10A 10mm x 14mm 123-pin LGA TRAY PI3302-20-LGIZ 5.0V 3.30 to 6.5V 10A 10mm x 14mm 123-pin LGA TRAY PI3303-20-LGIZ 12V 6.5 to 13.0V 8A 10mm x 14mm 123-pin LGA TRAY PI3305-20-LGIZ 15V 10.0 to 16.0V 8A 10mm x 14mm 123-pin LGA TRAY vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 3 of 26 PI33XX-X1 Pin Description Name Number Description 2 SGND Block 1 Signal ground: Internal logic ground for EA, TRK, SYNCI, SYNCO, ADJ and I C (options) communication returns. SGND and PGND are star connected within the regulator package. PGND Block 2 Power ground: VIN and VOUT power returns VIN Block 3 Input voltage: and sense for UVLO, OVLO and feed forward ramp VOUT Block 5 Output voltage: and sense for power switches and feed-forward ramp VS1 Block 4 Switching node: and ZVS sense for power switches PGD A1 Parallel Good: Used for parallel timing management intended for lead regulator. EAO A2 Error amp output: External connection for additional compensation and current sharing. EN A3 Enable Input: Regulator enable control. Asserted high or left floating – regulator enabled; 2 Asserted low, regulator output disabled. Polarity is programmable via I C interface. REM A5 Remote Sense: High side connection. Connect to output regulation point. ADJ B1 TRK C1 NC K3, A4 Adjust input: An external resistor may be connected between ADJ pin and SGND or VOUT to trim the output voltage up or down. Soft-start and track input: An external capacitor may be connected between TRK pin and SGND to decrease the rate of rise during soft-start. No Connect: Leave pins floating. Synchronization output: Outputs a low signal for ½ of the minimum period for synchronization of other converters. Synchronization input: Synchronize to the falling edge of external clock frequency. SYNCI is a high impedance digital input node and should always be connected to SGND when not in use. SYNCO K4 SYNCI K5 SDA D1 Data Line: Connect to SGND for PI33XX-10 and -11. For use with PI33XX-20 and -21 only. SCL E1 Clock Line: Connect to SGND for PI33XX-10 and -11. For use with PI33XX-20 and -21 only. ADR1 H1 Tri-state Address : No connect for PI33XX-10 and -11. For use with PI33XX-20 and -21 only. ADR0 G1 Tri-state Address : No connect for PI33XX-10 and -11. For use with PI33XX-20 and -21 only. SYNCI 2 SYNCO 1 NC Package Pin-Out 3 4 5 6 7 PGND Block 2 8 9 10 11 SGND K Block 1 J 12 13 14 VIN Block 3 Block 1: B2-4, C2-4, D2-3, E2-3, F1-3, G2-3, H2-3, J1-3, K1-2 ADR1 H Block 2: A8-10, B8-10, C8-10, D8-10, E4-10, F4-10, G4-10, H4-10, J4-10, K6-10 ADR0 G SGND F SCL E Block 3: G12-14, H12-14, J12-14, K12-14 SDA D TRK C VS1 Block 4 ADJ B PGD A REM NC EN EAO VOUT Block 5 123-Lead LGA (10mm x 14mm) Top view vicorpower.com 800 735.6200 Block 4: A12-14, B12-14, C12-14, D12-14, E12-14, Block 5: A6-7, B6-7, C6-7, D6-7 Rev 1.1 11/2012 ® Cool-Power Page 4 of 26 PI33XX-X1 Absolute Maximum Ratings Notes: At 25°C ambient temperature. All voltage nodes are referenced to PGND. VIN -0.7V to 36V VS1 -0.7 to 36V, -4V for 5ns VOUT See relevant product section SGND 100mA PGD, SYNCO, SYNCI, EN, EAO, ADJ, TRK, ADR1, ADR2, SCL, SDA, REM -0.3V to 5.5V / 5mA Storage Temperature -65°C to 150°C Operating Junction Temperature -40°C to 125°C Soldering Temperature for 20 seconds 260°C ESD Rating 2kV HBM VS1 VIN Q2 Q1 Vout VOUT R4 REM Power Control R1 EAO VCC ADJ - ZVS Control + 1V R2 SYNCO SYNCI PGD Memory EN TRK Interface PGND 0Ω ADR1 ADR0 SCL SDA SGND Figure 1: Simplified Block Diagram 2 (I C pins SCL, SDA, ADR0, and ADR1 only active for PI33XX-20 and PI33XX-21 versions) vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 5 of 26 PI33XX-X1 PI3311-X1 (1.0 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=80nH (Note 1) unless other conditions are noted. Parameter Input Specifications Symbol Min Typ Max Units Input Voltage VIN_DC 8 24 36 V Input Current IIN_DC Input Current At Output Short (fault condition duty cycle) 740 25 IIN_Short Input Quiescent Current IQ_VIN Input Voltage Slew Rate VIN_SR Output Specifications Output Voltage Total Regulation VOUT_DC Output Voltage Trim Range Line Regulation Load Regulation VOUT_DC mA 2 2.5 0.987 1.0 1.0 mA V/μs 1.013 1.4 V Note 2. Note 3. 0.1 0.1 Output Voltage Ripple VOUT_AC 45 mVp-p Continuous Output Current Range Current Limit Protection UVLO Start Threshold UVLO Stop Threshold IOUT_DC UVLO/OVLO Fault Delay Time UVLO/OVLO Response Time Output Over Voltage Protection Over-Temperature Fault Threshold Over-Temperature Restart Hysteresis 15 A A 16.5 VUVLO_START VUVLO_STOP 7.20 6.90 7.60 7.25 8.00 7.60 V V VUVLO_HYS VOVLO VOVLO_HYS 4 5 6 37 38.4 0.77 % V V tf_DLY 128 Cycles tf 500 20 135 ns % °C VOVP TOTP TOTP_HYS Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 130 Disabled Enabled (no load) 1 ∆VOUT(∆VIN) ∆VOUT(∆IOUT) UVLO Hysteresis OVLO Threshold OVLO Hysteresis Minimum 1mA load required Vin = 24V, TC = 25°C, Iout=15A mA V % % IOUT_CL Conditions 140 30 @25°C, 8V<Vin<36V @25°C, 0.5A<Iout<15A Iout=5A, Cout=8x100μF, 20MHz BW Note 4. Number of the switching frequency cycles +1% overdrive Above VOUT °C Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Rev 1.1 11/2012 ® Cool-Power Page 6 of 26 PI33XX-X1 PI3311-X1 (1.0 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=80nH (Note 1) unless other conditions are noted. Parameter Symbol Timing Switching Frequency Fault Restart Delay Min Typ Max 500 30 fS tFR_DLY Units kHz ms Conditions Note 6. Sync In (SYNCI) Synchronization Frequency Range ∆fSYNCI SYNCI Threshold Sync Out (SYNCO) VSYNCI SYNCO High SYNCO Low VSYNCO_HI VSYNCO_LO SYNCO Rise Time tSYNCO_RT SYNCO Fall Time tSYNCO_FT Soft Start And Tracking TRK Active Range (Nominal) VTRK VTRK_OV ITRK ITRK_DIS TRK Enable Threshold Charge Current (Soft – Start) Discharge Current (Fault) Soft-Start Time Enable 50 2.5 VEN_HI VEN_LO VEN_HYS 0.9 0.7 100 Source 1mA 0.5 10 20 ns 20pF load 10 20 ns 20pF load 1 V 40 -50 6.8 2.2 60 -30 2.6 mV µA mA ms 1 0.8 200 1.1 0.9 300 V V mV VEN_PU 2 V VEN_PD 0 V Source Current IEN_SO -50 uA Sink Current IEN_SK 50 uA unfaulted) Enable Pull-Down Voltage (floating, faulted) Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 Relative to set switching frequency. Note 3. V V 0 20 -70 % V 4.5 tSS High Threshold Low Threshold Threshold Hysteresis Enable Pull-Up Voltage (floating, 110 Sink 1mA CTRK = 0 Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Rev 1.1 11/2012 ® Cool-Power Page 7 of 26 PI33XX-X1 PI3311-X1 (1.0 Vout) Electrical Characteristics Efficiency (%) Efficiency at 25°C Transient Response: 7.5A to 15A, at 5A/µs 100 95 90 85 80 75 70 65 60 55 50 8Vin 12V in 24V in 36V in 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (A) Regulator and inductor performance 331101 Short Circuit Test 24Vin to 1.0Vout, Cout = 8X 100μF Ceramic Vout (Ch2) = 100mV/Div, Iout (Ch3) = 5A/Div, 200uS/Div 331102 Output Ripple: 24Vin, 1.0Vout at 15A Vout (Ch2) = 500mV/Div, Iin (Ch4) = 500mA/Div, 2ms/Div 331103 Cout = 8X 100µF Ceramic, Vout = 50mV/Div, 2.0us/Div 331104 Output ripple: 24Vin, 1.0Vout at 7A Switching Frequency vs. Load Current 600 Frequency (KHz) 500 400 300 200 8Vin 12Vin 24Vin 36Vin 100 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (A) 331105 vicorpower.com 800 735.6200 Cout = 8X 100µF Ceramic, Vout = 50mV/Div, 2.0us/Div Rev 1.1 11/2012 331106 ® Cool-Power Page 8 of 26 PI33XX-X1 PI3318-X1 (1.8 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted. Parameter Input Specifications Symbol Min Typ Max Units Input Voltage VIN_DC 8 24 36 V Input Current IIN_DC Input Current At Output Short (fault condition duty cycle) 1.25 45 IIN_Short Input Quiescent Current IQ_VIN Input Voltage Slew Rate VIN_SR Output Specifications Output Voltage Total Regulation Output Voltage Trim Range Line Regulation Load Regulation VOUT_DC VOUT_DC A 2 2.5 1 V/μs V V % % 1.8 1.823 1.4 2.0 ∆VOUT(∆VIN) ∆VOUT(∆IOUT) 1.8 0.1 0.1 Output Voltage Ripple VOUT_AC 30 Continuous Output Current Range Current Limit Protection IOUT_DC IOUT_CL 16.5 UVLO Start Threshold UVLO Stop Threshold UVLO Hysteresis OVLO Threshold OVLO Hysteresis VUVLO_START VUVLO_STOP VUVLO_HYS VOVLO VOVLO_HYS UVLO/OVLO Fault Delay Time UVLO/OVLO Response Time Output Over Voltage Protection Over-Temperature Fault Threshold Over-Temperature Restart Hysteresis mVp-p 15 A A 8.00 7.60 6 7.20 6.90 4 7.60 7.25 5 37 38.4 0.77 V V % V V tf_DLY 128 Cycles tf 500 20 ns % VOVP TOTP TOTP_HYS Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 130 135 140 30 Iout=15A mA mA 1.776 Conditions Disabled Enabled (no load) Note 2. Note 3. @25°C, 8V<Vin<36V @25°C, 0.5A<Iout<15A Iout=5A, Cout=8x100μF, 20MHz BW Note 4. Number of the switching frequency cycles +1% overdrive Above VOUT °C °C Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Rev 1.1 11/2012 ® Cool-Power Page 9 of 26 PI33XX-X1 PI3318-X1 (1.8 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted. Parameter Symbol Timing Switching Frequency Fault Restart Delay Min Typ Max 550 30 fS tFR_DLY Units kHz ms Conditions Note 6. Sync In (SYNCI) Synchronization Frequency Range ∆fSYNCI SYNCI Threshold Sync Out (SYNCO) VSYNCI SYNCO High SYNCO Low VSYNCO_HI VSYNCO_LO SYNCO Rise Time tSYNCO_RT SYNCO Fall Time tSYNCO_FT Soft Start And Tracking TRK Active Range (Nominal) VTRK VTRK_OV ITRK ITRK_DIS TRK Enable Threshold Charge Current (Soft – Start) Discharge Current (Fault) Soft-Start Time Enable 50 2.5 VEN_HI VEN_LO VEN_HYS 0.9 0.7 100 Source 1mA 0.5 10 20 ns 20pF load 10 20 ns 20pF load 1 V 40 -50 6.8 2.2 60 -30 2.6 mV µA mA ms 1 0.8 200 1.1 0.9 300 V V mV VEN_PU 2 V VEN_PD 0 V Source Current IEN_SO -50 uA Sink Current IEN_SK 50 uA unfaulted) Enable Pull-Down Voltage (floating, faulted) Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 Relative to set switching frequency. Note 3. V V 0 20 -70 % V 4.5 tSS High Threshold Low Threshold Threshold Hysteresis Enable Pull-Up Voltage (floating, 110 Sink 1mA CTRK = 0 Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Rev 1.1 11/2012 ® Cool-Power Page 10 of 26 PI33XX-X1 PI3318-X1 (1.8 Vout) Electrical Characteristics Efficiency(%) Efficiency at 25°C Transient Response: 7A to 15A, at 5A/µs 100 95 90 85 80 75 70 65 60 55 50 8Vin 12Vin 24Vin 36Vin 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (A) Regulator and inductor performance 331801 24Vin to 1.8Vout, Cout = 8X 100µF Ceramic Vout (Ch3) = 100mV/Div, Iin (Ch4) = 10A/Div, 80us/Div Short Circuit Test 331802 Output Ripple: 24Vin, 1.8Vout at 15A Vout (Ch3) = 500mV/Div, Iin (Ch2) = 1A/Div, 1ms/Div 331803 Switching Frequency vs. Load Current Cout = 8X 100µF Ceramic, Vout = 20mV/Div, 2.0us/Div 331804 Output ripple: 24Vin, 1.8Vout at 7.5A Switching Frequency(kHz) 600 500 400 300 200 100 8Vin 12Vin 24Vin 36Vin 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current(A) Cout = 8X 100µF Ceramic, Vout = 20mV/Div, 2.0us/Div 331805 vicorpower.com 800 735.6200 Rev 1.1 11/2012 331806 ® Cool-Power Page 11 of 26 PI33XX-X1 PI3312-X1 (2.5 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted. Parameter Input Specifications Symbol Min Typ Max Units Input Voltage VIN_DC 8 24 36 V Note 7. Input Current IIN_DC A Vin = 24V, TC = 25°C, Iout=15A Input Current At Output Short (fault condition duty cycle) 1.7 60 IIN_Short Input Quiescent Current IQ_VIN Input Voltage Slew Rate VIN_SR Output Specifications Output Voltage Total Regulation Output Voltage Trim Range VOUT_DC VOUT_DC 2 2.5 ∆VOUT (∆VIN) ∆VOUT (∆IOUT) 2.5 2.5 0.1 0.1 Output Voltage Ripple VOUT_AC 28 Continuous Output Current Range Current Limit Protection UVLO Start Threshold UVLO Stop Threshold UVLO Hysteresis IOUT_DC IOUT_CL Line Regulation Load Regulation OVLO Threshold OVLO Hysteresis UVLO/OVLO Fault Delay Time UVLO/OVLO Response Time Output Over Voltage Protection Over-Temperature Fault Threshold Over-Temperature Restart Hysteresis 2.465 2.0 mA mA V/μs 2.535 3.1 V V Note 2. % % @25°C, 8V<Vin<36V mVp-p 15 A A 8.00 7.60 6 V V % 16.5 7.20 6.90 4 7.60 7.25 5 VOVLO VOVLO_HYS 37 38.4 0.77 V V tf_DLY 128 Cycles tf 500 20 135 ns % °C TOTP_HYS Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 130 Disabled Enabled (no load) 1 VUVLO_START VUVLO_STOP VUVLO_HYS VOVP TOTP Conditions 140 30 Note 3. Note 7. @25°C, 0.5A<Iout<15A Iout=5A, Cout=8x100μF, 20MHz BW Note 7. Number of the switching frequency cycles +1% overdrive Above VOUT °C Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Note 7: Minimum 5V between Vin-Vout must be maintained or a minimum load of 1mA required. Rev 1.1 11/2012 ® Cool-Power Page 12 of 26 PI33XX-X1 PI3312-X1 (2.5 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted. Parameter Symbol Timing Switching Frequency Fault Restart Delay Min Typ Max 650 30 fS tFR_DLY Units kHz ms Conditions Note 6. Sync In (SYNCI) Synchronization Frequency Range ∆fSYNCI SYNCI Threshold Sync Out (SYNCO) VSYNCI SYNCO High SYNCO Low SYNCO Rise Time VSYNCO_HI VSYNCO_LO tSYNCO_RT SYNCO Fall Time tSYNCO_FT Soft Start And Tracking TRK Active Range (Nominal) TRK Enable Threshold Charge Current (Soft – Start) Discharge Current (Fault) Soft-Start Time Enable High Threshold Low Threshold Threshold Hysteresis Enable Pull-Up Voltage (floating, unfaulted) Enable Pull-Down Voltage (floating, faulted) Source Current Sink Current 50 110 0 20 -70 VEN_HI VEN_LO VEN_HYS 0.9 0.7 100 V Source 1mA 10 0.5 20 V V ns 10 20 ns 20pF load 1 60 -30 V mV µA mA 2.2 2.6 ms 1 0.8 200 1.1 0.9 300 V V mV 40 -50 6.8 VEN_PU 2 V VEN_PD 0 V IEN_SO IEN_SK -50 50 uA uA Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 Relative to set switching frequency. Note 3. 2.5 4.5 VTRK VTRK_OV ITRK ITRK_DIS tSS % Sink 1mA 20pF load CTRK = 0 Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Note 7: Minimum 5V between Vin-Vout must be maintained or a minimum load of 1mA required. Rev 1.1 11/2012 ® Cool-Power Page 13 of 26 PI33XX-X1 PI3312-X1 (2.5 Vout) Electrical Characteristics Efficiency (%) Efficiency at 25°C Transient Response: 7.5A to 15A, at 5A/µs 100 95 90 85 80 75 70 65 60 55 50 8Vin 12Vin 24Vin 36Vin 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (A) Regulator and inductor performance 331201 24Vin to 2.5Vout, Cout = 8 x 100µF Ceramic Vout (Ch1) = 200mV/Div, Iout (Ch4) = 5A/Div, 200us/Div 331202 Output Ripple: 24Vin, 2.5Vout at 15A Short Circuit Vout (Ch1) = 1V/Div, Iin (Ch4) = 1A/Div, 800us/Div 331203 Vout = 50mV/Div, 4.0us/Div, Cout = 8 x 100µF Ceramic 331204 Output Ripple: 24Vin, 2.5Vout at 7.5A Switching Frequency vs. Load Current Switching Frequency (kHz) 700 600 500 400 300 200 100 8Vin 12Vin 24Vin 36Vin 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (A) 331205 Vout = 50mV/Div, 4.0us/Div, Cout = 8 x 100µF Ceramic vicorpower.com 800 735.6200 Rev 1.1 11/2012 331206 ® Cool-Power Page 14 of 26 PI33XX-X1 PI3301-X1 (3.3 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=155nH (Note 1) unless other conditions are noted. Parameter Input Specifications Symbol Min Typ Max Units Input Voltage VIN_DC 8 24 36 V Note 7. Input Current IIN_DC A Vin = 24V, TC = 25°C, Iout=15A Input Current At Output Short (fault condition duty cycle) 2.25 75 IIN_Short Input Quiescent Current IQ_VIN Input Voltage Slew Rate VIN_SR Output Specifications Output Voltage Total Regulation Output Voltage Trim Range VOUT_DC VOUT_DC 2 2.5 ∆VOUT(∆VIN) ∆VOUT(∆IOUT) 3.30 3.3 0.10 0.10 Output Voltage Ripple VOUT_AC 37.5 Continuous Output Current Range Current Limit Protection UVLO Start Threshold UVLO Stop Threshold UVLO Hysteresis IOUT_DC IOUT_CL Line Regulation Load Regulation OVLO Threshold OVLO Hysteresis UVLO/OVLO Fault Delay Time UVLO/OVLO Response Time Output Over Voltage Protection Over-Temperature Fault Threshold Over-Temperature Restart Hysteresis 3.25 2.3 mA mA V/μs 3.36 4.1 V V Note 2. % % @25°C, 8<Vin<36V mVp-p 15 A A 8.00 7.60 6 V V % 16.5 7.20 6.90 4 7.60 7.25 5 VOVLO 37 VOVLO_HYS 38.4 0.77 V V tf_DLY 128 Cycles tf 500 20 135 ns % °C TOTP_HYS Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 130 Disabled Enabled (no load) 1 VUVLO_START VUVLO_STOP VUVLO_HYS VOVP TOTP Conditions 140 30 Note 3. Note 7. @25°C, 0.5A<Iout<15A Iout=5A, Cout=8x100μF, 20MHz BW Note 4. Note 7. Number of the switching frequency cycles +1% overdrive Above VOUT °C Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Note 7: Minimum 5V between Vin-Vout must be maintained or a minimum load of 1mA required. Rev 1.1 11/2012 ® Cool-Power Page 15 of 26 PI33XX-X1 PI3301-X1 (3.3 Vout) Electrical Characteristics Specifications apply for -40C < TJ < 125C, Vin =24V, L1=155nH (Note 1) unless other conditions are noted. Parameter Symbol Timing Switching Frequency Fault Restart Delay Min Typ Max 650 30 fS tFR_DLY Units kHz ms Conditions Note 6. Sync In (SYNCI) Synchronization Frequency Range ∆fSYNCI SYNCI Threshold Sync Out (SYNCO) VSYNCI SYNCO High SYNCO Low VSYNCO_HI VSYNCO_LO SYNCO Rise Time tSYNCO_RT SYNCO Fall Time tSYNCO_FT Soft Start And Tracking TRK Active Range (Nominal) VTRK VTRK_OV ITRK ITRK_DIS TRK Enable Threshold Charge Current (Soft – Start) Discharge Current (Fault) Soft-Start Time Enable 50 2.5 VEN_HI VEN_LO VEN_HYS 0.9 0.7 100 Source 1mA 0.5 10 20 ns 20pF load 10 20 ns 20pF load 1 V 40 -50 6.8 2.2 60 -30 2.6 mV µA mA ms 1 0.8 200 1.1 0.9 300 V V mV VEN_PU 2 V VEN_PD 0 V Source Current IEN_SO -50 uA Sink Current IEN_SK 50 uA unfaulted) Enable Pull-Down Voltage (floating, faulted) Note 1: All parameters reflect regulator and inductor system performance. Measurements were made using a standard PI33XX evaluation board with 3x4” dimensions and 4 layer, 2oz copper. Refer to inductor pairing table within Application Description section for specific inductor manufacturer and value. Note 2: Regulator is assured to meet performance specifications by design, test correlation, characterization, and/or statistical process control. vicorpower.com 800 735.6200 Relative to set switching frequency. Note 3. V V 0 20 -70 % V 4.5 tSS High Threshold Low Threshold Threshold Hysteresis Enable Pull-Up Voltage (floating, 110 Sink 1mA CTRK = 0 Note 3: Output current capability may be limited and other performance may vary from noted electrical characteristics when switching frequency or Vout is modified. Note 4: Refer to Output Ripple plots. Note 5: Refer to Load Current vs. Ambient Temperature curves. Note 6: Refer to Switching Frequency vs. Load current curves. Note 7: Minimum 5V between Vin-Vout must be maintained or a minimum load of 1mA required. Rev 1.1 11/2012 ® Cool-Power Page 16 of 26 PI33XX-X1 PI3301-X1 (3.3 Vout) Electrical Characteristics Efficiency (%) Efficiency at 25°C Transient Response: 7.5 to 15A, at 5A/µs 100 95 90 85 80 75 70 65 60 55 50 8Vin 12Vin 24Vin 36Vin 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (A) Regulator and inductor performance 330101 24Vin to 3.3Vout, Cout = 8 x 100µF Ceramic Vout (Ch1) = 200mV/Div, Iout (Ch4) = 5A/Div, 200us/Div 330102 Output Ripple: 24Vin, 3.3Vout at 15A Short Circuit Vout (Ch1) = 1V/Div, Iout (Ch4) = 1A/Div, 800us/Div 330103 Vout = 50mV/Div, 2.0us/Div, Cout = 8 x 100µF Ceramic 330104 Output Ripple: 24Vin, 3.3Vout at 7.5A Switching Frequency vs. Load Current Swicthing Frequency (kHz) 800 700 600 500 400 300 200 100 8Vin 12Vin 24Vin 36Vin 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (A) 330105 vicorpower.com 800 735.6200 Vout = 50mV/Div, 2.0us/Div, Cout = 8 x 100µF Ceramic Rev 1.1 11/2012 330106 ® Cool-Power Page 17 of 26 PI33XX-X1 Functional Description The PI33XX is a family of highly integrated ZVS-Buck regulators. The PI33XX has a set output voltage that is trimmable within a prescribed range shown in Table 1. Performance and maximum output current are characterized with a specific external power inductor (see Table 5). L1 Vin Vin Cin PGND Vout VS1 PI33XX Cout Vout REM SYNCI TRK ADJ EN EAO SGND SYNCO Figure 2 - ZVS-Buck with required components For basic operation, Figure 2 shows the connections and components required. No additional design or settings are required. ENABLE (EN) EN is the enable pin of the converter. The EN Pin is referenced to SGND and permits the user to turn the converter on or off. The EN default polarity is a positive logic assertion. If the EN pin is left floating or asserted high, the converter output is enabled. Pulling EN pin below 0.8 Vdc with respect to SGND will disable the regulator output. The EN input polarity can be programmed (PI33XX-20 2 and PI33XX-21 versions only) via the I C data bus. When the EN pin polarity is programmed for negative logic assertion; and if the EN pin is left floating, the regulator output is enabled. Pulling the EN pin above 1.0 Vdc with respect to SGND, will disable the regulator output. Switching Frequency Synchronization The SYNCI input allows the user to synchronize the controller switching frequency by an external clock referenced to SGND. The external clock can synchronize the unit between 50% and 110% of the preset switching frequency (fS). For PI33XX-20 and PI33XX-21 versions only, the phase delay can be programmed via I2C bus with respect to the clock vicorpower.com 800 735.6200 applied at SYNCI pin. Phase delay allows PI33XX regulators to be paralleled and operate in an interleaving mode. The PI33XX default for SYNCI is to sync with respect to the falling edge of the applied clock providing 180° phase shift from SYNCO. This allows for the paralleling of two PI33XX devices without the need for further user programming or external sync clock circuitry. The user can change the SYNCI polarity to 2 sync with the external clock rising edge via the I C data bus (PI33XX-20 and PI33XX-21 versions only). When using the internal oscillator, the SYNCO pin provides a 5V clock that can be used to sync other regulators. Therefore, one PI33XX can act as the lead regulator and have additional PI33XXs running in parallel and interleaved. Output Voltage Trim The PI33XX output voltage can be trimmed up from the preset output by connecting a resistor from ADJ pin to SGND and can be trimmed down by connecting a resistor from ADJ pin to VOUT. The Table 2 defines the voltage ranges for the PI33XX family. Device PI3311-X1-LGIZ PI3318-X1-LGIZ PI3312-X1-LGIZ PI3301-X1-LGIZ Output Voltage Set 1.0V 1.8V 2.5V 3.3V Range 1.0 to 1.4V 1.4 to 2.0V 2.0 to 3.1V 2.3 to 4.1V Table 2 - PI33XX family output voltage ranges. Soft-Start The PI33XX includes an internal soft-start capacitor to ramp the output voltage in 2ms from 0V to full output voltage. Connecting an external capacitor from the TRK pin to SGND will increase the start-up ramp period. See, “Soft Start Adjustment and Track,” in the Applications Description section for more details. Remote Sensing An internal 100Ω resistor is connected between REM pin and VOUT pin to provide regulation when the Rev 1.1 11/2012 ® Cool-Power Page 18 of 26 PI33XX-X1 REM is left open. With REM open, the converter will regulate 100mV above its set point. Connect REM to the desired reference node to be regulated. Output Current Limit Protection PI33XX has two methods implemented to protect from output short or over current condition. Slow Current Limit protection: prevents the output load from sourcing current higher than the regulator’s maximum rated current. If the output current exceeds the Current Limit (IOUT_CL) for 1024us, a slow current limit fault is initiated and the regulator is shutdown which eliminates output current flow. After Fault Restart Delay (tFR_DLY), a soft-start cycle is initiated. This restart cycle will be repeated indefinitely until the excessive load is removed. Fast Current Limit protection: PI33XX monitors the regulator inductor current pulse-by-pulse to prevent the output from supplying very high current due to a sudden low impedance short. If the regulator senses a high inductor current pulse, it will initiate a fault and stop switching until Fault Restart Delay ends and then initiate a soft-start cycle. Both the Fast and Slow current limit faults are stored in a Fault Register and can be read and cleared (PI33XX-20 and PI33XX-21 versions only) via I2C data bus. Input Under-Voltage Lockout If VIN falls below the input Under Voltage Lockout (UVLO) threshold, but remains high enough to power the internal bias supply, the PI33XX will complete the current cycle and stop switching. If VIN recovers within 128 switching cycles, the PI33XX will resume normal operation. If this time limit is exceeded, the system will enter a low power state and initiate a fault. The system will restart once the input voltage is reestablished and after the Fault Restart Delay. A UVLO fault is stored in a Fault Register and can be read and cleared (PI33XX-20 and PI33XX-21 versions 2 only) via I C data bus. Input Over Voltage Lockout If VIN exceeds the input Over Voltage Lockout (OVLO) threshold (VOVLO), while the controller is running, the vicorpower.com 800 735.6200 PI33XX will complete the current cycle and stop switching. If VIN recovers within 128 switching cycles, the PI33XX will resume normal operation. Otherwise, the system will enter a low power state and sets an OVLO fault. The system will resume operation when the input voltage falls below 98% of the OVLO threshold and after the Fault Restart Delay. The OVLO fault is stored in a Fault Register and can be read and cleared (PI33XX-20 and PI33XX-21 versions only) via I2C data bus. Output Over Voltage Protection The PI33XX family is equipped with output Over Voltage Protection (OVP) to prevent damage to input voltage sensitive devices. If the output voltage exceeds 20% of its set regulated value, the regulator will complete the current cycle, stop switching and issue an OVP fault. The system will resume operation once the output voltage falls below the OVP threshold and after Fault Restart Delay. The OVP fault is stored in a Fault Register and can be read and cleared (PI33XX-20 and PI33XX-21 versions only) via 2 I C data bus. Over Temperature Protection The internal package temperature is monitored to prevent internal components from reaching their thermal maximum. If the Over Temperature Protection Threshold (OTP) is exceeded (TOTP), the regulator will complete the current switching cycle, enter a low power mode, set a fault flag, and will soft-start when the internal temperature falls below Over-Temperature Restart Hysteresis (TOTP_HYS). The OTP fault is stored in a Fault Register and can be read and cleared (PI33XX-20 and PI33XX-21 versions only) 2 via I C data bus. Pulse Skip Mode (PSM) PI33XX features a PSM to achieve high efficiency at light loads. The regulators are setup to skip pulses if EAO falls below a PSM threshold. Depending on conditions and component values, this may result in single pulses or several consecutive pulses followed by skipped pulses. Skipping cycles significantly reduces gate drive power and improves light load Rev 1.1 11/2012 ® Cool-Power Page 19 of 26 PI33XX-X1 efficiency. The regulator will leave PSM once the EAO rises above the Skip Mode threshold. phase with each other reducing output ripple (refer to Switching Frequency Synchronization). Variable Frequency Operation To provide synchronization between regulators over the entire operational frequency range, the Parallel Good (PGD) pin must be connected to the lead regulator’s SYNCI pin and a 2.5kΩ Resistor, R1, must be placed between SYNCO return and the lead regulator’s SYNCI pin, as shown in Figure 3. In this configuration, at system soft-start, the PGD pin pulls SYNCI low forcing the lead regulator to initialize the open-loop startup synchronization. Once the regulators reach regulation, SYNCI is released and the system is now synchronized in a closed-loop configuration which allows the system to adjust, on the fly, when any of the individual regulators begin to enter variable frequency mode in the loop. Each PI33XX is preprogrammed to a base operating frequency, with respect to the power stage inductor (see Table 5), to operate at peak efficiency across line and load variations. At low line and high load applications, the base frequency will decrease to accommodate these extreme operating ranges. By stretching the frequency, the ZVS operation is preserved throughout the total input line voltage range therefore maintaining optimum efficiency. Parallel Operation Paralleling multiple PI33XX modules can be used to increase the output current capability of a single power rail and reduce output voltage ripple. L1 Vin Vin Vout VS1 Vout Cin Cout PGND PI33XX R1 SYNCO REM PGD SYNCI SYNCI EN SYNCO EN EAO EAO TRK TRK SGND I2C Interface Operation L1 Vin Vin VS1 Vout Cin Cout PGND PI33XX PGD SYNCO SYNCI SYNCI SYNCO EN REM EN EAO EAO TRK TRK Multi-phasing three regulators is possible (PI33XX-20 and PI33XX-21 only) with no change to the basic single-phase design. For more information about how to program phase delays within the regulator, please refer to Picor application note PI33XX-2X Multi-Phase Design Guide. SGND Figure 3 - PI33XX parallel operation By connecting the EAO pins and SGND pins of each module together the units will share the current equally. When the TRK pins of each unit are connected together, the units will track each other during soft-start and all unit EN pins have to be released to allow the units to start (See Figure 3). Also, any fault event in any regulator will disable the other regulators. The two regulators will be out of vicorpower.com 800 735.6200 PI33XX-20 and PI33XX-21 provide an I2C digital interface that enables the user to program the EN pin polarity (from high to low assertion) and switching frequency synchronization phase/delay. These are one time programmable options to the device. Also, the PI33XX-20 and PI33XX-21 allow for dynamic Vout margining via I2C that is useful during development (settings stored in volatile memory only and not retained by the device). The PI33XX-20 and PI33XX-21 also have the option for fault telemetry including: Over temperature protection Fast/Slow current limit Output voltage high Input overvoltage Input undervoltage Rev 1.1 11/2012 ® Cool-Power Page 20 of 26 PI33XX-X1 2 For more information about how to utilize the I C interface please refer to Picor application note 2 PI33XX-2X I C Digital Interface Guide. output. The internal resistor value for each regulator is listed below in Table 4. Application Description Output Voltage Trim The PI33XX family of Buck Regulators provides seven common output voltages: 1.0V, 1.8V, 2.5V, 3.3V, 5.0V, 12V and 15V. A post-package trim step is implemented to offset any resistor divider network errors ensuring maximum output accuracy. With a single resistor connected from the ADJ pin to SGND or REM, each device’s output can be varied above or below the nominal set voltage (with the exception of the PI3311-X1 which can only be above the set voltage of 1V). Output Voltage Device PI3311-X1-LGIZ PI3318-X1-LGIZ PI3312-X1-LGIZ PI3301-X1-LGIZ Set Range 1.0V 1.8V 2.5V 3.3V 1.0 to 1.4V 1.4 to 2.0V 2.0 to 3.1V 2.3 to 4.1V Table 3 - PI33XX family output voltage ranges The remote pin (REM) should always be connected to the VOUT pin, if not used, to prevent an output voltage offset. Figure 4 shows the internal feedback voltage divider network. VOUT R4 REM R_low R1 ADJ + R_high R2 1.0Vdc Device R1 R2 PI3311-X1-LGIZ PI3318-X1-LGIZ PI3312-X1-LGIZ PI3301-X1-LGIZ 1k 0.806k 1.5k 2.61k Open 1.0k 1.0k 1.13k R4 100 100 100 100 Table 4 - PI33XX Internal divider values By choosing an output voltage value within the ranges stated in Table 3, VOUT can simply be adjusted up or down by selecting the proper R_high or R_low value, respectively. The following equations can be used to calculate R_high and R_low values: ( ( ) ) ( ( ) ) ( ( ) ) If, for example, a 4.0V output is needed, the user should choose the regulator with a trim range covering 4.0V from Table 3. For this example, the PI3301 is selected (3.3V set voltage). First step would be to use Equation (1) to calculate R_high since the required output voltage is higher than the regulator set voltage. The resistor-divider network values for the PI3301 are can be found in Table 4 and are R1=2.61kΩ and R2=1.13kΩ. Inserting these values in to Equation (1), R_high is calculated as follows: SGND ( ) ( ) Figure 4 - Internal resistor divider network R1, R2, and R4 are all internal 1.0 % resistors and R_low and R_high are external resistors for which the designer can add to modify VOUT to a desired vicorpower.com 800 735.6200 Resistor R-high would be connected as in Figure 4 to achieve the 4.0V regulator output. No R_low resistor would be used since in this example the trim is above the regulator set voltage. Rev 1.1 11/2012 ® Cool-Power Page 21 of 26 PI33XX-X1 Master VOUT Soft-Start Adjust and Tracking The TRK pin offers a means to increase the regulator’s soft-start time or to track with additional regulators. The soft-start slope is controlled by an internal 100nF and a fixed charge current to provide a minimum startup time of 2ms (typical) for all PI33XX regulators. By adding an additional external capacitor to the TRK pin, the soft-start time can be increased further. The following equation can be used to calculate the proper capacitor for a desired soft-start times: ( ) Where, tTRK is the soft-start time and ITRK is a 50uA internal charge current (see Electrical Characteristics for limits). There is typically either proportional or direct tracking implemented within a design. For proportional tracking between several regulators at startup, simply connect all devices TRK pins together. This type of tracking will force all connected regulators to startup and reach regulation at the same time (see Figure 5 (a)). TRK Slave VOUT 2 R2 SGND Figure 6 - Voltage divider connections for direct tracking All connected regulators’ soft-start slopes will track with this method. Direct tracking timing is demonstrated in Figure 5 (b). All tracking regulators should have their Enable (EN) pins connected together to work properly. Inductor Pairing The PI33XX utilizes an external inductor. This inductor has been optimized for maximum efficiency performance. Table 5 details the specific inductor value and part number utilized for each PI33XX device and are manufactured by Picor. Device PI3311-X1 PI3318-X1 PI3312-X1 PI3301-X1 VOUT 1 R1 PI33XX Inductor [nH] 80 125 125 155 Inductor Part Number PI6080-00-FPIZ PI6125-00-FPIZ PI6125-00-FPIZ PI6155-00-FPIZ Manufacturer Picor Picor Picor Picor Table 5 - PI33XX Inductor pairing (a) Master VOUT VOUT 2 (b) t Figure 5 - PI33XX tracking methods For Direct Tracking, choose the regulator with the highest output voltage as the master and connect the master to the TRK pin of the other regulators through a divider (Figure 6) with the same ratio as the slave’s feedback divider (see Table 4 for values). vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 22 of 26 PI33XX-X1 Layout Guidelines To optimize maximum efficiency and low noise performance from a PI33XX design, layout considerations are necessary. Reducing trace resistance and minimizing high current loop returns along with proper component placement will contribute to optimized performance. A typical buck converter circuit is shown in Figure 9. The potential areas of high parasitic inductance and resistance are the circuit return paths, shown as LR below. When Q1 is on and Q2 is off, the majority of CIN’s current is used to satisfy the output load and to recharge the COUT capacitors. When Q1 is off and Q2 is on, the load current is supplied by the inductor and the COUT capacitor as shown in Figure 11. During this period CIN is also being recharged by the VIN. Minimizing CIN loop inductance is important to reduce peak voltage excursions when Q1 turns off. Also, the difference in area between the CIN loop and COUT loop is vital to minimize switching and GND noise. Figure 9 - Typical Buck Converter The path between the COUT and CIN capacitors is of particular importance since the AC currents are flowing through both of them when Q1 is turned on. Figure 10, schematically, shows the reduced trace length between input and output capacitors. The shorter path lessens the effects that copper trace parasitics can have on the PI33XX performance. Figure 11 - Current flow: Q2 closed The recommended component placement, shown in Figure 12, illustrates the tight path between CIN and COUT (and VIN and VOUT) for the high AC return current. This optimized layout is used on the PI33XX evaluation board. Figure 10 - Current flow: Q1 closed Figure 12 - Recommended component placement and metal routing vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 23 of 26 PI33XX-X1 Recommended PCB Footprint and Stencil Figure 13 - Recommended Receiving PCB footprint. Figure 133 details the recommended receiving footprint for PI33XX 10mm x 14mm package. All pads should have a final copper size of 0.55mm x 0.55mm, whether they are solder-mask defined or copper defined, on a 1mm x 1mm grid. All stencil openings are 0.55mm when using a 6mil stencil. vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 24 of 26 PI33XX-X1 Package Drawings vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 25 of 26 PI33XX-X1 Warranty Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor for its use. Vicor makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication. Vicor reserves the right to make changes to any products, specifications, and product descriptions at any time without notice. Information published by Vicor has been checked and is believed to be accurate at the time it was printed; however, Vicor assumes no responsibility for inaccuracies. Testing and other quality controls are used to the extent Vicor deems necessary to support Vicor’s product warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. Specifications are subject to change without notice. Vicor’s Standard Terms and Conditions All sales are subject to Vicor’s Standard Terms and Conditions of Sale, which are available on Vicor’s webpage or upon request. Product Warranty In Vicor’s standard terms and conditions of sale, Vicor warrants that its products are free from non-conformity to its Standard Specifications (the “Express Limited Warranty”). This warranty is extended only to the original Buyer for the period expiring two (2) years after the date of shipment and is not transferable. 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As used herein, life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. Per Vicor Terms and Conditions of Sale, the user of Vicor products and components in life support applications assumes all risks of such use and indemnifies Vicor against all liability and damages. Intellectual Property Notice Vicor and its subsidiaries own Intellectual Property (including issued U.S. and Foreign Patents and pending patent applications) relating to the products described in this data sheet. No license, whether express, implied, or arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Interested parties should contact Vicor's Intellectual Property Department. The products described on this data sheet are protected by the following U.S. Patents Numbers: RE 40,072. Vicor Corporation 25 Frontage Road Andover, MA, USA 01810 USA Picor Corporation 51 Industrial Drive North Smithfield, RI 02896 USA Customer Service: [email protected] Technical Support: [email protected] vicorpower.com 800 735.6200 Rev 1.1 11/2012 ® Cool-Power Page 26 of 26