NCP1588 Low Voltage Synchronous Buck Controller The NCP1588 is a low cost PWM controller designed to operate from a 5 V or 12 V supply. This device is capable of producing an output voltage as low as 0.8 V. This device is capable of converting voltage from as low as 2.5 V. This 10-pin device provides an optimal level of integration to reduce size and cost of the power supply. The NCP1588 provides a 1.5 A gate driver design and an internally set 300kHz oscillator. In addition to the 1.5 A gate drive capability, other efficiency enhancing features of the gate driver include adaptive non-overlap circuitry. The NCP1588 also incorporates an externally compensated error amplifier. Protection features include programmable short circuit protection and undervoltage lockout (UVLO). Features •VCC Range from 4.5 to 13.2 V •300 kHz Internal Oscillator •Boost Pin Operates to 26.4 V •Voltage Mode PWM Control •0.8 V ±1.0% Internal Reference Voltage •Adjustable Output Voltage •Internal 1.5 A Gate Drivers •80% Max Duty Cycle •Input Under Voltage Lockout •Programmable Current Limit •This is a Pb-Free Device http://onsemi.com MARKING DIAGRAM 1588 ALYWG G DFN10 MT SUFFIX CASE 485C 1588 A L Y W G = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week = Pb-Free Device (Note: Microdot may be in either location) PIN CONNECTIONS PGOOD BOOT 1 10 LX 2 9 VOS UG 3 8 FB LG 4 7 COMP/EN GND 5 6 VCC Applications (Top View) •Graphics Cards •Desktop Computers •Servers / Networking •DSP & FPGA Power Supply •DC-DC Regulator Modules ORDERING INFORMATION Device Package Shipping† NCP1588MTR2G DFN10 (Pb-Free) 3000/Tape & Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. © Semiconductor Components Industries, LLC, 2007 June, 2007 - Rev. 0 1 Publication Order Number: NCP1588/D NCP1588 VIN = 2.5 V - 13.2 V 3x22mF VBST = 4.5 V - 15 V 1500mF VCC = 4.5 V - 13.2 V 1mF 2x0.22mF 1500mF VCC NTD4809 BOOT PGOOD 0.1mF COMP/EN UG R2 17.08kW LG GND C3 0.014mF R3 74.2W R9 R10 2x1800mF 4.7nF 1.02k R1 4.12kW 1.02k R4 3.878kW VOS VOUT 1.65 V 1mH 2.2 FB NTD4806 LX C2 0.007mF ROCSET C1 0.0015mF GND Figure 1. Typical Application Diagram PGOOD PGOOD MONITOR OV and UV VOS 9 ±10% of Vref ±25% of Vref 0.8 V (VREF) POR UVLO 8 - + + 0.8 V (VREF) + LATCH FAULT FB 10 6 VCC 1 BOOT 3 UG 2 LX 4 LG 5 GND VOCP FAULT R S PWM OUT Q + - CLOCK RAMP COMP/EN 7 2V + SOFT START - OSC OSC FAULT Figure 2. Detailed Block Diagram http://onsemi.com 2 VCC NCP1588 PIN FUNCTION DESCRIPTION Pin No. Symbol Description 1 BOOT Supply rail for the floating top gate driver. To form a boost circuit, use an external diode to bring the desired input voltage to this pin (cathode connected to BOOT pin). Connect a capacitor (CBOOT) between this pin and the LX pin. Typical values for CBOOT range from 0.1 mF to 1 mF. Ensure that CBOOT is placed near the IC. 2 LX Switch node pin. This is the reference for the floating top gate driver. Connect this pin to the source of the top MOSFET. 3 UG Top gate MOSFET driver pin. Connect this pin to the gate of the top N-channel MOSFET. 4 LG Bottom gate MOSFET driver pin. Connect this pin to the gate of the bottom N-channel MOSFET. 5 GND IC ground reference. All control circuits are referenced to this pin. 6 VCC Supply rail for the internal circuitry. Operating supply range is 4.5 V to 13.2 V. Decouple with a 1 mF capacitor to GND. Ensure that this decoupling capacitor is placed near the IC. 7 COMP/EN Compensation Pin. This is the output of the error amplifier (EA) and the non-inverting input of the PWM comparator. Use this pin in conjunction with the FB pin to compensate the voltage-control feedback loop. Pull this pin low for disable. 8 FB 9 VOS 10 PGOOD This pin is the inverting input to the error amplifier. Use this pin in conjunction with the COMP pin to com‐ pensate the voltage-control feedback loop. Connect this pin to the output resistor divider (if used) or directly to Vout. Offset voltage pin from Vout. Power Good output. Open drain type output that is flagged low if ±10% of Vout. ABSOLUTE MAXIMUM RATINGS Pin Name Main Supply Voltage Input Bootstrap Supply Voltage Input Switching Node (Bootstrap Supply Return) Symbol VMAX VMIN VCC 15 V -0.3 V BOOT 30 V wrt/GND 38-40 V < 100 ns 15 V wrt/LX -0.3 V LX 25 V 30 V for < 100 ns -5 V High-Side Driver Output (Top Gate) UG 30 V wrt/GND 15 V wrt/LX 40 V for < 100 ns -0.3 V wrt/LX Low-Side Driver Output (Bottom Gate) LG VCC + 0.3 V -0.3 V -2 V < 100 ns FB, VOS 3.6 V -0.3 V COMP/EN 3.6 V -0.3 V PGOOD 7V -0.3 V Symbol Value Unit Thermal Resistance, Junction-to-Ambient RqJA 165 °C/W Thermal Resistance, Junction-to-Case Feedback, VOS COMP/EN PGOOD MAXIMUM RATINGS Rating RqJC 45 °C/W NCP1588 Operating Junction Temperature Range TJ 0 to 150 °C NCP1588 Operating Ambient Temperature Range TA 0 to 70 °C Storage Temperature Range Tstg -55 to +150 °C Moisture Sensitivity Level MSL 1 260 Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. http://onsemi.com 3 NCP1588 ELECTRICAL CHARACTERISTICS (0°C < TA < 70°C, 0°C < TJ < 125°C (NCP1588); 4.5 V < VCC < 13.2 V, 4.5 V < BOOT < 26.4 V, CUG = CLG = 1.0 nF (REF:NTD30N02), for min/max values unless otherwise noted.) Characteristic Conditions Input Voltage Range Boost Voltage Range 13.2 V wrt LX Min Typ Max Unit 4.5 13.2 V 4.5 26.4 V 1.75 mA Supply Current Quiescent Supply Current VFB = 1.0 V, No Switching, VCC = 13.2 V 1.0 Boost Quiescent Current VFB = 1.0 V, No Switching 140 mA Undervoltage Lockout UVLO threshold VCC Rising Edge 3.8 UVLO hysteresis 4.0 0.37 V V Switching Regulator VFB Feedback Voltage, control loop in regulation TA = 0 to 70°C 0.792 0.8 0.808 V Oscillator Frequency TA = 0 to 70°C 270 300 330 KHz Ramp-Amplitude Voltage Minimum Duty Cycle Maximum Duty Cycle 70 LG minimum on time 1.1 V 0 % 75 80 500 % ns Error Amplifier Open loop dc gain Output source current Output sink current 70 Vfb < 0.8 V Vfb > 0.8 V Input Offset Voltage 80 DB 2.0 2.0 -2.0 Input Bias Current Unity Gain Bandwidth 15 Disable Threshold 0.3 mA 0 2.0 mV 0.1 1.0 mA Mhz Output Sink current during disable 0.5 V 100 mA Gate Drivers Upper Gate source VCC = 5 V, VUG - VLX = 2.5 V 1.5 Upper Gate sink W 1.4 Lower Gate source Lower Gate sink A 1.5 A W VCC = 12 V 1.0 UG falling to LG rising delay VCC = 12 V, UG-LX < 2.0 V, LG > 2.0 V 30 90 ns LG falling to UG rising delay VCC = 12 V, LG < 2.0 V, UG > 2.0 V 30 60 ns 7.0 ms 0.4 V Soft-Start Soft-Start time 3.0 Power Good Output Saturation Voltage IPG = 4 mA, VCC = 12 Vdc OVP threshold to part disable 1.0 V UVP threshold to part disable 0.6 V OVP threshold to PGOOD output low 0.88 V UVP threshold to PGOOD output low 0.72 V 10 mA Overcurrent Protection OC Current source Sourced from LG pin, before SS http://onsemi.com 4 NCP1588 TYPICAL CHARACTERISTICS 305 808 806 VREF, REFERENCE (mV) fSW, FREQUENCY (kHz) VCC = 12 V 303 VCC = 5.0 V 301 299 297 804 802 800 798 796 794 295 0 20 40 60 792 0 80 20 TJ, JUNCTION TEMPERATURE (°C) Figure 3. Oscillator Frequency (fSW) vs. Temperature 80 -556 -558 OCP THRESHOLD (mV) 3.5 3.0 ICC (mA) 60 Figure 4. Reference Voltage (VREF) vs. Temperature 4.0 2.5 2.0 1.5 1.0 0 40 TJ, JUNCTION TEMPERATURE (°C) -560 -562 -564 -566 -568 -570 20 40 60 0 80 20 40 60 TJ, JUNCTION TEMPERATURE (°C) TJ, JUNCTION TEMPERATURE (°C) Figure 5. ICC vs. Temperature Figure 6. OCP Threshold with 55k Rset vs. Temperature http://onsemi.com 5 80 NCP1588 APPLICATIONS INFORMATION Overcurrent Protection (OCP) Internal Soft –Start The low-side RDSon sense is implemented by comparing the voltage at the LX, at the end of LG on time to an internally generated fixed voltage. If the phase voltage is lower than OCP trip voltage, an overcurrent condition occurs and a counter is initiated. When the counter completes after two clock cycles, the PWM logic and both HS-FET and LS-FET are turned off. Power has to be recycled to exit out of the overcurrent fault. The minimum turn-on time of the LS-FET is set to be 500 ns. NCP1588 allows to easily program an Overcurrent Threshold ranging from 50 mV to 550 mV, simply by adding a resistor (ROCSET) between LG and GND. During a short period of time following VCC rising over UVLO threshold, an internal 10 mA current (IOCSET) is sourced from LG pin, determining a voltage drop across ROCSET. This voltage drop will be sampled and internally held by the device as OverCurrent Threshold. The OC setting procedure overall time length is about 4.2 ms. Connecting a ROCSET resistor between LG and GND, the programmed threshold will be: The NCP1588 features an internal soft-start function, which reduces the inrush current and overshoot of the output voltage. Figure 7. shows a typical soft-start sequence. Soft-Start is achieved by ramping the internal reference using the oscillator clock (64 steps from 0 V to 0.8 V of VREF). The order of startup sequence is as follows: UVLO → OCP programming → Comp voltage reach the lower end of the Ramp voltage (1.1 V). The typical soft-start time is 4.2 ms. The internal soft-start is held low when the part is in UVLO or Disable mode. I OCth + Power Good Power Good is an open drain and active high output. This output can be pulled up high to the appropriate level with an external resistor. It monitors the output voltage through the VOS pin. The PGOOD is flagged low for ±10% of Vout for OV/UV trip points respectively. The separate VOS input is not slowed down by the compensation on the VFB pin. The PGOOD output can deliver a max of 4 mA sink current at 0.4 V when de-asserted. The PGOOD pin is held low during soft-start. Once soft-start is complete PGOOD goes high if there are no faults without any delays associated to it. I OCSET @ R OCSET Undervoltage Protection R DS(on) If the voltage at VOS pin drops below UV threshold, the device turns off both HS and LS MOSFETs, latching the condition. This requires a POR to recover. RSET values range from 5 kW to 55 kW. In case ROCSET is not connected, the device switches the OCP threshold to a fixed 640 mV value: an internal safety clamp on BG is triggered as soon as LG voltage reaches 700 mV, enabling the 640 mV fixed threshold and ending OC setting phase. The current trip threshold tolerance is ±25 mV. The accuracy of the set point is best at the highest set point. The accuracy will decrease as the set point decreases. Overvoltage Protection If the voltage at VOS pin rises over OV threshold (1V typ), overvoltage protection turns off UG MOSFET and turns on LG MOSFET. The LG MOSFET will be turned off as soon as VOS goes below Vref/2 (0.4 V). The condition is latched, and requires POR to recover. The device still controls the LG MOSFET and can switch it on whenever VOS rises above 0.4 V. http://onsemi.com 6 NCP1588 4.0 V 3.6 V VCC UVLO Fault 1.1 V COMP -0.7 V 700 mV 50 mV OCP UG Program‐ mable LG VOUT 0.8 V Vfb UV Monitor POR UVLO SS NORMAL Figure 7. Typical Startup Sequence http://onsemi.com 7 NCP1588 VOS 1.0V 0.88V 0.8V 0.88V 0.8V 0.72V 0.6V 0.4V PG UG LG Overvoltage Undervoltage Figure 8. Typical Power Good Function Feedback and Compensation Design Example: The NCP1588 allows the output voltage to be adjusted from 0.8 V to 5.0 V via an external resistor divider network. The controller will try to maintain 0.8 V at feedback pin. Thus, if a resistor divider circuit was placed across the feedback pin to VOUT, the controller will regulate the output voltage proportional to the resistor divider network in order to maintain 0.8 V at the FB pin. The same formula applies to the VOS pin and the controller will maintain 0.8 V at the VOS pin. Voltage Mode Control Loop with TYPE III Compensation Converter Parameters: Input Voltage: VIN = 5 V Output Voltage: VOUT = 1.65 V Switching Frequency: 300 kHz Total Output Capacitance: COUT = 3600 mF Total ESR: ESR = 6 mW Output Inductance: LOUT: 1 mH Ramp Amplitude: VRAMP = 1 V VOUT C1 R1 FB R3 C3 R2 C2 R4 VOUT Figure 9. VCOMP VREF ǒVOUTVREF Ǔ * VREF Figure 10. a.. Set a target for the close loop bandwidth at 1/6th of the switching frequency. The same formula can be applied to the feedback resistors at VOS. R9 + R10 E/A + R4 The relationship between the resistor divider network above and the output voltage is shown in the following equation: R4 + R1 R1 ǒVOUTVREF Ǔ * VREF F cross_over :+ 50kHz http://onsemi.com 8 NCP1588 Step 5: Place 2nd zero at the output filter double pole frequency. b.. Output Filter Double Pole Frequency F lc :+ 1 2 @ p @ Ǹ L OUT @ C OUT R3 :+ Step 6: Place 2nd pole at half the switching frequency. 1 2 @ p @ C OUT @ C ESR C3 :+ F ESR + 7.368kHz Step 2: Pick compensation DC gain (R2/R1) for desired close loop bandwidth. R4 :+ V RAMP :+ 1.1V Ǔǒ V RAMP @ Ǔ F lc R1 = 4.12 kW R2 = 17.085 kW R3 = 74.169 W R4 = 3.878 kW C1 = 0.0015 mF C2 = 0.007 mF C3 = 0.014 mF NOTE: Recommend to change values to industry standard component values. 2 @ ǸL OUT @ C OUT R2 10 - 3mF Step 4: Place 1st pole at ESR zero frequency. C1 :+ C2 C2 @ R2 @ 2 @ p @ F ESR * 1 C1 + 1.542 V OUT * V REF The Component values for Type III Compensation are: Step 3: Place 1st zero at half the output filter double pole frequency. C2 + 7.024 V REF @ R1 R4 + 3.878kW F cross_over R2 + 17.085kW C2 :+ ǒ p @ R3 @ FSWǓ Step 7: R4 is sized to maintain the feedback voltage to VREF = 0.8 V. R1 :+ 4.12kW V IN 1 C3 + 0.014mF Step 1: Set a value for R1 between 2 kW and 5 kW ǒ *1 lc R3 + 74.169W c.. ESR Zero Frequency: R2 :+ R1 @ SW 2@F F lc + 2.653kHz F ESR :+ R1 F 10 - 3mF http://onsemi.com 9 NCP1588 PACKAGE DIMENSIONS DFN10, 3x3, 0.5P CASE 485C-01 ISSUE A D PIN 1 REFERENCE 0.15 C 2X A B ÇÇÇ ÇÇÇ ÇÇÇ L1 E DETAIL A Bottom View (Optional) ÉÉ ÉÉ EXPOSED Cu TOP VIEW 0.15 C 2X MOLD CMPD (A3) DETAIL B 0.10 C A1 A 10X SIDE VIEW A1 D2 C 1 DIM A A1 A3 b D D2 E E2 e K L L1 MILLIMETERS MIN MAX 0.80 1.00 0.00 0.05 0.20 REF 0.18 0.30 3.00 BSC 2.45 2.55 3.00 BSC 1.75 1.85 0.50 BSC 0.19 TYP 0.35 0.45 0.00 0.03 DETAIL A e L A3 DETAIL B Side View (Optional) SEATING PLANE 0.08 C 10X NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. DIMENSION b APPLIES TO PLATED TERMINAL AND IS MEASURED BETWEEN 0.25 AND 0.30 MM FROM TERMINAL. 4. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. 5. TERMINAL b MAY HAVE MOLD COMPOUND MATERIAL ALONG SIDE EDGE. MOLD FLASHING MAY NOT EXCEED 30 MICRONS ONTO BOTTOM SURFACE OF TERMINAL b. 6. DETAILS A AND B SHOW OPTIONAL VIEWS FOR END OF TERMINAL LEAD AT EDGE OF PACKAGE. EDGE OF PACKAGE SOLDERING FOOTPRINT* 5 2.6016 E2 10X K 10 10X 0.10 C A B 0.05 C 6 2.1746 b 1.8508 3.3048 BOTTOM VIEW NOTE 3 10X 0.5651 10X 0.3008 0.5000 PITCH DIMENSIONS: MILLIMETERS *For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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