NCP1406, NCV1406 25 V/25 mA PFM Step-Up DC-DC Converter The NCP1406 is a monolithic step−up DC−DC converter operating in a Pulse Frequency Modulation (PFM) scheme with constant peak current control. It integrates a 0.8 A, 0.7 W internal power switch and sensing resistor to monitor inductor current. This control scheme maintains high efficiencies over the entire load current range. The wide input voltage range, from 1.4V to 5.5 V, enables the user to operate the device from a Li−Ion battery or a two−cell Alkaline NiMH. Its ability to boost voltages up to 25 V, and to provide 1 W output power, makes the NCP1406 the perfect solution for biasing small and large OLED panels. This device also makes a perfect solution for biasing a great number of white LEDs in series. A Chip Enable pin allows the user to control the device to extend the battery life during standby, and can be pulse−width modulated for white LED applications. The versatility of the NCP1406 allows it to be configured not only as a step−up converter, but also as an inverter and as a step−down converter. This solution is proposed in a space−saving TSOP−5 package. Features • • • • • • • • • • • • 87% Efficiency at VOUT = 25 V, IOUT = 25 mA, VIN = 5 V Adjustable Output Voltage up to 25 V 0.8 A, 26 V Internal Power Switch Operating Input Voltage from 1.4 V to 5.5 V Low Startup Voltage of 1.8 V Typical at No Load Low Operating Current of 15 mA (Not Switching) Low Shutdown Current of 0.3 mA Operating Switching Frequency up to 1 MHz Output Voltage Soft−Start Thermal Shutdown Protection These are Pb−Free Devices NCV Prefix for Automotive and Other Applications Requiring Unique Site and Control Change Requirements; AEC−Q100 Qualified and PPAP Capable Typical Applications • • • • • LCD Bias Supplies Small and Large OLED Display Drivers White LED Driver for Backlight Displays Personal Digital Assistants (PDA) Portable Applications: ♦ Cell Phones, Digital Cameras ♦ PDAs, Games, and Portable Video Players © Semiconductor Components Industries, LLC, 2012 October, 2012 − Rev. 6 http://onsemi.com MARKING DIAGRAM 5 5 1 TSOP−5/SOT23−5/SC59−5 SN SUFFIX CASE 483 XXX AYW G G 1 DAM = Device Marking − NCP1406 AET = Device Marking − NCV1406 A = Assembly Location Y = Year W = Work Week G = Pb−Free Package (Note: Microdot may be in either location) PIN CONNECTIONS CE 1 FB 2 VDD 3 5 LX 4 GND (Top View) ORDERING INFORMATION Device Package Shipping† NCP1406SNT1G TSOP−5 (Pb−Free) 3000 Tape & Reel NCV1406SNT1G TSOP−5 (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 Specification Brochure, BRD8011/D. 1 Publication Order Number: NCP1406/D NCP1406, NCV1406 100 VOUT 15 V D SUMIDA CR43−8R2MC VDD Enable CE OLED CIN 10 mF CC 68 pF R2 1.3 mW LX FB GND R1 110 kW 5.0 V 4.2 V 3.7 V 90 EFFICIENCY (%) L 8.2 mH VIN 2.4 V 3.0 V 80 2.4 V VOUT = 15 V L1 = 8.2 mH, Sumida CR43−8R2MC C1 = 10 mF C2 = 4.7 mF C3 = 68 pF TA = 25°C Figure 4 VIN = 2.0 V 70 COUT 4.7 mF 60 0 20 40 60 IOUT, OUTPUT CURRENT (mA) Figure 1. Typical Application Circuit Figure 2. Efficiency versus Output Current L1 8.2 mH VIN 2.0 V to 5.5 V FB 2 VDD 3 Enable MBR0530T1 VOUT 25 V LX 5 NCP1406 CE 1 C1 10 mF D1 C2 3.3 mF C3 82 pF R1 2.2 MW GND 4 R2 110 kW ǒ Ǔ ǒ Ǔ R VOUT + 1.19 1 ) 1 R2 Figure 3. Typical 25 V Step−Up Application Circuit L1 8.2 mH C1 10 mF Enable CE 1 FB 2 VDD 3 MBR0520T1 VOUT 15 V LX 5 NCP1406 VIN 2.0 V to 5.5 V D1 C2 4.7 mF C3 68 pF GND 4 R1 1.3 MW R2 110 kW R VOUT + 1.19 1 ) 1 R2 Figure 4. Typical 15 V Step−Up Application Circuit http://onsemi.com 2 80 NCP1406, NCV1406 L1 8.2 mH VIN 2.0 V to 5.5 V FB 2 VDD 3 Enable MBR0520T1 VOUT 8V LX 5 NCP1406 CE 1 C1 10 mF D1 C2 4.7 mF C3 12 pF R1 620 kW GND 4 R2 110 kW ǒ Ǔ R VOUT + 1.19 1 ) 1 R2 Figure 5. Typical 8 V Step−Up Application Circuit LX VDD Thermal Shutdown UVLO TSD FB + CS PFM PFM Comparator Bandgap 1.2 V Current Sense Soft−Start EN Driver FB_P FB Fault Protection Enable CE GND Figure 6. Representative Block Diagram PIN FUNCTION DESCRIPTION Pin Symbol Description 1 CE Chip Enable Pin (1) The chip is enabled if a voltage which is equal to or greater than 0.9 V is applied. (2) The chip is disabled if a voltage which is less than 0.3 V is applied. (3) The chip will be enabled if it is left floating. 2 FB Output feedback voltage. Connected to the inverting input of the PFM comparator. 3 VDD Power supply pin for internal circuit 4 GND Analog and power ground pin 5 LX External inductor connection pin. Connected to the drain of the NMOS internal switch. http://onsemi.com 3 NCP1406, NCV1406 MAXIMUM RATINGS Symbol Value Unit Power Supply Voltage (Pin 3) Rating VDD −0.3 to 6.0 V Input/Output Pin LX (Pin 5) LX Peak Sink Current FB (Pin 2) VLX ILX VFB −0.3 to 27 1.5 −0.3 to 6.0 V A V CE (Pin 1) Input Voltage Range VCE −0.3 to 6.0 V Power Dissipation and Thermal Characteristics Maximum Power Dissipation @ TA = 25_C Thermal Resistance, Junction−to−Air PD RqJA 500 250 mW _C/W TA −40 to +85 −40 to +105 _C TJ −40 to +150 _C Tstg −55 to +150 _C Operating Ambient Temperature Range NCP1406 NCV1406 Operating Junction Temperature Range Storage Temperature Range 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. 1. This device series contains ESD protection and exceeds the following tests: Human Body Model (HBM) "2.0 kV per JEDEC standard: JESD22−A114 for all pins Machine Model (MM) "200 V per JEDEC standard: JESD22−A115 for all pins 2. Latchup Current Maximum Rating: "150 mA per JEDEC standard: JESD78 3. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A DISSIPATION RATINGS Package Power Rating @TA 255C Derating Factor @TA 255C Power Rating @TA = 705C Power Rating @TA = 855C Power Rating @TA = 1055C TSOP−5 500 mW 4.0 mW/°C 320 mW 260 mW 180 mW http://onsemi.com 4 NCP1406, NCV1406 ELECTRICAL CHARACTERISTICS (VOUT = 25 V, TA = −40_C to +85_C (NCP1406), TA = −40_C to +105_C (NCV1406) for min/max values, typical values are at TA = 25_C, unless otherwise noted.) Characteristic Symbol Min Typ Max Unit Minimum Off Time (VDD = 3.0 V, VFB = 0 V) toff 0.08 0.13 0.20 ms Maximum On Time (Current Not Asserted) ton 0.58 0.90 1.40 ms Maximum Duty Cycle DMAX 84 90 96 % Minimum Startup Voltage (IOUT = 0 mA) Vstart − 1.8 2.0 V DVstart − 1.6 − mV/°C Vhold − 1.7 1.9 V tSS − 3.0 8.0 ms ON/OFF TIMING CONTROL Minimum Startup Voltage Temperature Coefficient (TA = −40 to +105°C) Minimum Hold Voltage (IOUT = 0 mA) Soft−Start Time LX (PIN 5) Internal Switch Voltage (Note 4) (Note 5) VLX − − 26 V Rsw(on) − 0.7 − W Current Limit (When ILX reaches ILIM, the LX switch is turned off by the LX switch protection circuit) (Note 5) ILIM − 0.80 − A Off−State Leakage Current (VLX = 26 V) ILKG − 0.1 1.0 mA CE Input Voltage (VDD = 3.0 V, VFB = 0 V) High State, Device Enabled Low State, Device Disabled VCE(high) VCE(low) 0.9 − − − − 0.3 V V CE Input Current High State, Device Enabled (VDD = VCE = 5.5 V) Low State, Device Disabled (VDD = 5.5 V, VCE = VFB = 0 V) ICE(high) ICE(low) − −500 10 −150 500 − nA nA VDD 1.4 − 5.5 V VUVLO − 1.0 1.3 V VFB 1.178 1.170 1.190 1.190 1.202 1.210 V IFB − 15 45 nA Operating Current 1 (VFB = 0 V, VDD = VCE = 3.0 V, Maximum Duty Cycle) IDD1 − 0.7 1.5 mA Operating Current 2 (VDD = VCE = VFB = 3.0 V, Not Switching) IDD2 − 15 25 mA Off−State Current (VDD = 5.0 V, VCE = 0 V) IOFF − 0.3 1.3 mA Thermal Shutdown (Note 5) TSD − 140 − °C TSDHYS − 10 − °C LX Pin On−State Resistance (VLX = 0.4 V, VDD = 5.0 V) CE (PIN 1) TOTAL DEVICE Supply Voltage Undervoltage Lockout (VDD Falling) Feedback Voltage TA = 25°C TA = −40 to +105°C Feedback Pin Bias Current (VFB = 1.19 V) Thermal Shutdown Hysteresis (Note 5) 4. Recommended maximum VOUT up to 25 V. 5. Guaranteed by design, not tested. http://onsemi.com 5 NCP1406, NCV1406 TYPICAL CHARACTERISTICS 100 100 4.2 V 5.0 V 90 80 VOUT = 25 V L1 = 8.2 mH, Sumida CR43−8R2MC C1 = 10 mF C2 = 3.3 mF C3 = 82 pF TA = 25°C Figure 3 3.7 V 3.0 V VIN = 2.4 V 70 60 0 10 20 EFFICIENCY (%) EFFICIENCY (%) 90 30 40 80 2.4 V 70 VIN = 2.0 V 5 10 IOUT, OUTPUT CURRENT (mA) 20 25 30 Figure 8. Efficiency versus Output Current (VOUT = 25 V, L = 10 mH) 100 100 5.0 V 4.2 V 3.7 V 90 3.0 V 80 2.4 V VOUT = 15 V L1 = 8.2 mH, Sumida CR43−8R2MC C1 = 10 mF C2 = 4.7 mF C3 = 68 pF TA = 25°C Figure 4 VIN = 2.0 V 70 60 0 20 40 60 VOUT = 15 V L1 = 10 mH, Sumida CMD4D11−100MC C1 = 10 mF C2 = 4.7 mF C3 = 120 pF TA = 25°C Figure 4 70 10 20 30 40 50 60 IOUT, OUTPUT CURRENT (mA) Figure 9. Efficiency versus Output Current (VOUT = 15 V, L = 8.2 mH) Figure 10. Efficiency versus Output Current (VOUT = 15 V, L = 10 mH) 100 100 2.4 V 3.7 V 3.0 V VIN = 2.0 V VOUT = 8.0 V L1 = 8.2 mH, Sumida CR43−8R2MC C1 = 10 mF C2 = 4.7 mF C3 = 12 pF TA = 25°C Figure 5 70 25 4.2 V 50 75 100 125 5.0 V 90 5.0 V EFFICIENCY (%) 90 60 0 3.7 V 3.0 V VIN = 2.0 V IOUT, OUTPUT CURRENT (mA) 80 2.4 V 80 60 0 80 5.0 V 4.2 V 90 EFFICIENCY (%) EFFICIENCY (%) 15 IOUT, OUTPUT CURRENT (mA) Figure 7. Efficiency versus Output Current (VOUT = 25 V, L = 8.2 mH) EFFICIENCY (%) VOUT = 25 V L1 = 10 mH, Sumida CMD4D11−100MC C1 = 10 mF C2 = 3.3 mF C3 = 150 pF TA = 25°C Figure 3 3.7 V 3.0 V 60 0 50 5.0 V 4.2 V 80 3.0 V IOUT, OUTPUT CURRENT (mA) 25 4.2 V 3.7 V VOUT = 8.0 V L1 = 10 mH, Sumida CMD4D11−100MC C1 = 10 mF C2 = 4.7 mF C3 = 20 pF TA = 25°C Figure 5 70 60 0 150 VIN = 2.0 V 2.4 V 50 75 IOUT, OUTPUT CURRENT (mA) Figure 11. Efficiency versus Output Current (VOUT = 8 V, L = 8.2 mH) Figure 12. Efficiency versus Output Current (VOUT = 8.0 V, L = 10 mH) http://onsemi.com 6 100 NCP1406, NCV1406 TYPICAL CHARACTERISTICS 1.2 ton, MAXIMUM ON TIME (ms) VFB, FEEDBACK VOLTAGE (V) 1.22 1.20 1.18 1.16 1.1 1.0 0.9 0.8 0.7 VDD = 3.0 V 1.14 −50 −25 0 25 50 75 0.6 −50 100 TA, AMBIENT TEMPERATURE (°C) 25 50 75 100 toff, MINIMUM OFF TIME (ms) IDD1, OPERATING CURRENT 1 (mA) 1000 0.16 0.14 0.12 0.10 VDD = 3.0 V −25 0 25 50 75 900 MAXIMUM DUTY CYCLE OPERATION 800 700 600 500 −50 100 TA, AMBIENT TEMPERATURE (°C) VDD = VCE = 3.0 V VFB = 0 V −25 0 25 50 75 100 TA, AMBIENT TEMPERATURE (°C) Figure 15. Minimum Off Time versus Ambient Temperature Figure 16. Operating Current 1 versus Ambient Temperature 25 1000 20 IOFF, OFF−STATE CURRENT (nA) IDD2, OPERATING CURRENT 2 (mA) 0 Figure 14. Maximum On Time versus Ambient Temperature 0.18 NOT SWITCHING 15 10 5 VDD = VCE = VFB = 3.0 V 0 −50 −25 TA, AMBIENT TEMPERATURE (°C) Figure 13. Feedback Voltage versus Ambient Temperature 0.08 −50 VDD = 3.0 V −25 0 25 50 75 800 600 400 200 0 −50 100 TA, AMBIENT TEMPERATURE (°C) VDD = 5.0 V VCE = 0 V −25 0 25 50 75 TA, AMBIENT TEMPERATURE (°C) Figure 17. Operating Current 2 versus Ambient Temperature Figure 18. Off−State Current versus Ambient Temperature http://onsemi.com 7 100 NCP1406, NCV1406 TYPICAL CHARACTERISTICS 0.5 IIN, NO LOAD INPUT CURRENT (mA) tss, SOFT−START TIME (ms) 6 5 4 3 2 1 0 −50 −25 0 25 50 75 100 VOUT = 25 V L1 = 8.2 mH D1 = MBR0530LT1 C1 = 10 mF C2 = 3.3 mF C3 = 82 pF R1 = 2.2 MW R2 = 110 kW TA = 25°C 0.4 0.3 0.2 0.1 0 1 2 TA, AMBIENT TEMPERATURE (°C) RSW(on), SWITCH−ON RESISTANCE (W) ILIMIT, CURRENT LIMIT (A) 1.0 0.9 0.8 0.7 0 25 50 5 6 Figure 20. No Load Input Current versus Input Voltage 1.1 −25 4 VIN, INPUT VOLTAGE (V) Figure 19. Soft−start Time versus Ambient Temperature 0.6 −50 3 75 100 1.4 1.2 1.0 TA = 85°C 0.8 TA = 25°C 0.6 0.4 TA = −40°C 1 2 3 4 5 TA, AMBIENT TEMPERATURE (°C) VIN, INPUT VOLTAGE (V) Figure 21. Current Limit versus Ambient Temperature Figure 22. Switch−ON Resistance versus Input Voltage L1 = 8.2 mH, C1 = 10 mF, C2 = 4.7 mF, VIN = 3.7 V 1. VOUT = 15 V (AC Coupled), 100 mV/div 2. IOUT = 1.0 mA to 20 mA, 20 mA/div 6 L1 = 8.2 mH, C1 = 10 mF, C2 = 4.7 mF, IOUT = 15 mA 1. VOUT = 15 V (AC Coupled), 100 mV/div 2. VIN = 3.0 V to 4.0 V, 2.0 V/div Figure 23. Load Transient Response (VOUT = 15 V) Figure 24. Line Transient Response (VOUT = 15 V) http://onsemi.com 8 NCP1406, NCV1406 TYPICAL CHARACTERISTICS L1 = 8.2 mH, C1 = 10 mF, C2 = 3.3 mF, VIN = 4.2 V, VOUT = 25 V, IOUT = 30 mA 1. VLX, 10 V/div 2. IL, 200 mA/div 3. Vripple, 50 mV/div L1 = 8.2 mH, C1 = 10 mF, C2 = 3.3 mF, VIN = 4.2 V, VOUT = 25 V, IOUT = 5.0 mA 1. VLX, 10 V/div 2. IL, 200 mA/div 3. Vripple, 50 mV/div Figure 26. Operating Waveforms (Heavy Load) Figure 25. Operating Waveforms (Light Load) L1 = 8.2 mH, C1 = 10 mF, C2 = 3.3 mF, VIN = 4.2 V, IOUT = 20 mA 1. VCE, 0 V to 1.0 V to 0 V, 1.0 V/div 2. IL, 500 mA/div 3. VOUT, 10 mV/div Figure 27. Startup/Shutdown Waveforms (VOUT = 25 V) 4.0 VOUT = 25 V L1 = 10 mH, Sumida CMD4D11−100MC C1 = 10 mF C2 = 3.3 mF D1 = MBR0530LT1 Figure 3 TA = 25°C 3.0 2.0 1.0 0 0 5 10 15 20 IOUT, OUTPUT CURRENT (mA) 25 Figure 28. Startup/Shutdown Waveforms (VOUT = 15 V) 5.0 VSTART, STARTUP VOLTAGE (V) 5.0 VSTART, STARTUP VOLTAGE (V) L1 = 8.2 mH, C1 = 10 mF, C2 = 4.7 mF, VIN = 4.2 V, IOUT = 25 mA 1. VCE, 0 V to 1.0 V to 0 V, 1.0 V/div 2. IL, 500 mA/div 3. VOUT, 10 mV/div 4.0 3.0 2.0 1.0 0 30 VOUT = 15 V L1 = 10 mH, Sumida CMD4D11−100MC C1 = 10 mF C2 = 4.7 mF D1 = MBR0520LT1 Figure 4 TA = 25°C 0 5 10 15 20 IOUT, OUTPUT CURRENT (mA) Figure 30. Startup Voltage versus Input Voltage (VOUT = 15 V) Figure 29. Startup Voltage versus Input Voltage (VOUT = 25 V) http://onsemi.com 9 25 NCP1406, NCV1406 SIMPLIFIED OPERATING DESCRIPTION Operation Figure 31 depicts the three phases of operation in DCM in a simplified way. During the first interval, the switch is turned on and the diode is reverse biased. The inductor stores energy through the battery while the load is supplied by the output capacitor to maintain regulation. During the second interval, the switch is turned off and the diode is forward biased, this allows the energy stored in the inductor to be supplied to both the load and the capacitor. During the third interval, the switch is kept off and the diode is reverse biased, the capacitor supplies the current to the load. In DCM, the voltage ratio can be expressed as: The NCP1406 is a monolithic DC−DC switching converter optimized for single Lithium, two− or three−cell AA/AAA size battery−powered portable products. The NCP1406 operates in a Pulse Frequency Modulation (PFM) scheme with constant peak current control. This scheme maintains high efficiencies over the entire load current range. The device is designed to operate in Discontinuous Conduction Mode (DCM). When the inductor releases its energy to the output and its current reaches zero before a new cycle starts, the converter is said to operate in DCM. If a new cycle starts before the inductor current reaches zero, the converter is said to operate in Continuous Conduction Mode (CCM). The operation of the NCP1406 is not limited to the discontinuous conduction mode. The device can also be operated in continuous conduction mode, but its stability is not guaranteed. 1 ) Ǹ1 ) 4 VOUT + VIN 2 T Where D + ON , TSW L D VL VD VSW − VIN VL − C + VOUT R VIN TON TIDLE L D VL VD − IC = IO L R C TOFF TIDLE VOUT TON IL + VIN VL − C TOFF TIDLE ISW IAVG Time Time VSW ID VIN 1 2 3 IOUT TSW VOUT IL = ID = IC + IO IC = IO L + R C TOFF TON IL 2 L VOUT (eq. 1) Unlike in CCM, the voltage ratio of a boost converter in DCM is load dependent. + VIN KD + D2 K IO Time 1 2 3 Figure 31. Simplified Boost Converted Operation− Discontinuous Mode http://onsemi.com 10 Time R VOUT NCP1406, NCV1406 Current Limit The detailed operation of NCP1406 can be best understood by referring to the block diagram and typical application circuits in Figures 1, 3, 4, and 5. The PFM comparator monitors the output voltage via the external feedback resistor divider by comparing the feedback voltage with the reference voltage. When the feedback voltage is lower than the reference voltage, the PFM controller and driver circuit turn the internal switch on and the current ramps up in the inductor. The switch will remain on for the maximum on−time, 0.90 ms, or until the current limit is reached (0.8 A), whichever occurs first. The internal switch is then turned off and the inductor current ramps down. The energy stored in the inductor will be discharged to the output capacitor and load through the Schottky diode. The internal switch will be turned off for at least the minimum off−time, 0.13 ms, and will remain off until the feedback voltage becomes lower than the reference voltage. If the inductor current reaches zero before then, the Schottky diode will be reverse biased and the output capacitor will sustain the regulation by providing current to the load, while the switch pin will be left floating. The switch will turn back on when the feedback voltage becomes again lower than reference voltage. This switching cycle is then repeated to attain voltage regulation. The device operating current is typically 15 mA (not switching), and can be further reduced to about 0.3 mA when the chip is disabled (VCE < 0.3 V). The current limit circuit limits the maximum current flowing through the LX pin to a typical of 0.8 A during the internal switch turn−on period. When the current limit is exceeded, the switch will be turned off. Since the peak inductor current is limited to the current limit, saturation of inductor is prevented and output voltage over−shoot during startup is also minimized. Internal Switch The NCP1406 integrates a 26 V open drain internal switch which allows high output voltage up to 25 V to be generated from simple step−up topology. FB Pin Short−Circuit/Open−Circuit Protection The FB protection circuit is realized by sensing the drain−to−source leakage current of the N−Ch MOSFET. When the FB pin connection is shorted or opened, the converter switches at maximum duty cycle, the peak of VLX and the VOUT will build up, and the leakage current will increase. When the leakage current increases to a certain level, the protection circuitry will trigger and the converter will stop switching. Therefore, the peak of VLX will immediately stop increasing at a certain level before the N−Ch MOSFET is damaged. However, the sensing of the leakage current is not very accurate and cannot be too close to the normal 26 V maximum operating condition. Therefore, the VLX is around 30 V to 40 V during a FB pin protection fault. This is not destructive to the chip though. Soft Start There is a soft start circuit in NCP1406. When power is applied to the device, the soft−start circuit limits the device to switch at a small duty cycle initially. The duty cycle is then increased gradually until the output voltage is in regulation. With the soft−start circuit, the output voltage over−shoot is minimized and the startup capability with heavy loads is also improved. Input Undervoltage Lockout An undervoltage lockout circuit continuously monitors the voltage at the VDD pin. The device will be disabled if the VDD pin voltage drops below the UVLO threshold voltage. In the same manner, the device will be enabled if the VDD pin voltage goes above the UVLO threshold. Thermal Shutdown ON/OFF Timing Control When the chip junction temperature exceeds 140°C, the entire IC is shutdown. The IC will resume operation when the junction temperature drops below 130°C. The timing control of the converter is application dependent. The maximum on−time (inductor current ramping up) is set at a typical 0.9 ms if the inductor current does not reach current limit 0.8 A. The minimum off−time (inductor current ramping down) is set at a typical 0.13 ms to ensure the complete energy transfer to the output. The switching frequency can be as high as 1.0 MHz. Enable/Disable Operation An external pin, CE, allows the user to enable or disable the converter. This feature proves useful when the system is in a standby mode by increasing battery life through significantly decreased current consumption. A 150 nA pull−up current source ties the CE pin to the VDD pin internally. Therefore, leaving the CE pin floating will enable the NCP1406. With no other connections to the CE pin, it can be independently controlled by an external signal. When the voltage at the CE pin is equal to or greater than 0.9 V, the chip will be enabled, which means the device is in normal operation. When the voltage at the CE pin is less than 0.3 V, Voltage Reference and Output Voltage The internal bandgap voltage reference is trimmed to 1.19 V with an accuracy of "1.0% at 25°C. The voltage reference is connected to the non inverting input of the PFM comparator and the inverting input of the PFM comparator is connected to the FB pin. The output voltage can be set by connecting an external resistor divider to the output and using the FB pin. The output voltage programmable range is from VIN to 25 V. http://onsemi.com 11 NCP1406, NCV1406 the chip is disabled and is shutdown. During shutdown, the IC supply current reduces to 0.3 mA and the LX pin enters high impedance state. However, the input remains connected to the output through the inductor and the Schottky diode, keeping the output voltage one diode forward voltage drop below the input voltage. When the NCP1406 is used to drive white LEDs, the EN pin can be pulse width modulated to control LED brightness. V IOUT + IN 2 FSW + Inductor Because it uses a PFM peak current control scheme in DCM, the NCP1406 is inherently stable. The inductor value does not affect the stability of the device. The NCP1406 is designed to work well with a range of inductance values; the actual inductance value depends on the specific application, output current, efficiency, and output ripple voltage. For step−up conversion, the device works well with inductance ranging from 1 mH to 47 mH. The selection of the inductor value along with the load current, input and output voltages determines the switching frequency at which the converter will operate. In general, an inductor with small DCR is used to minimize loss and increase efficiency. It is necessary to choose an inductor with saturation current greater than the peak switching current in the application. A lower inductor value increases the switching frequency, hence increases the losses which yields a lower overall efficiency. As stated before, the NCP1406 is designed to operate in DCM. Stable operation in CCM is not guaranteed. For all the mathematical equations given below, VIN is the input voltage, TON_MAX is the maximum on−time which is typically 0.9 ms, ILIM is the current limit which is typically 0.8 A, L is the selected inductance, VOUT is the desired output voltage, VD is the Schottky diode forward voltage, and h is the conversion efficiency which can be assumed typically 80% for better margin for estimation. IOUT + TIDLE IPK = VIN IL Time IO IPK h (eq. 4) ǒ Ǔ 2 VIN2 TON L (VOUT ) VD) (eq. 5) h * IOUT If IROOM < 0, the converter operates in continuous conduction mode. If IROOM = 0, the converter operates in critical conduction mode. If IROOM > 0, the converter operates in discontinuous conduction mode. The Discontinuous Conduction Mode For each switching cycle, if the internal MOSFET is switched on, it will be switched off only when either the maximum on−time, TON, of typical 0.9 ms is reached or the inductor current limit of 0.8 A is met, whichever is earlier. Therefore, the designer can choose to use either the maximum on−time or the current limit to turn off the internal switch. Minimizing the output ripple voltage If the aim is to minimize output ripple voltage, the maximum on−time of 0.9 ms should be used to turn off the MOSFET; however, the maximum output current will be reduced. It is critical to ensure that the maximum on−time has been reached before the current limit is met. TSW TON_MAX t L VIN The on−time (inductor ramp up) can be expressed as following: L TON + V IN D VIN2 TON L (VOUT ) VD) 2 IROOM + TON L D2 = TOFF (1 − D) OUT 2 L IOUT VOUT ) VD *1 h VIN VIN TON2 One can determine the mode of operation using the factor IROOM defined as: D = TON TSW IPK (eq. 3) ǒ1 * h VOUTVIN)VDǓ ǒ1 ) h V VIN)V ǒD12 * 1ǓǓ FSW(load) + Mode determination TOFF 1 )VD ǒD12 * 1Ǔ ) VOUT h VIN In the above equations, D2 gives us the information about the mode of operation (DCM or CCM). The value of D2 will increase as load increases until it reaches 1, which corresponds to the state of critical conduction when the inductor current starts ramping up immediately after it reaches zero (starting a new cycle). The value of the output current and the switching frequency at the critical mode transition (D2 = 1) can be expressed as following: External Component Selection TON TON TON L ILIM (eq. 6) To ensure this condition is met, the inductance L should be selected according to the following equation: (eq. 2) Lu The output current and the switching frequency can be expressed as following: http://onsemi.com 12 VIN ILIM TON_MAX (eq. 7) NCP1406, NCV1406 achieve, and double pulsing or group pulsing will occur which will lead to much larger inductor current ripple and result in larger output ripple voltage. The switching frequency at nominal load is expressed as: FSW(load) + 2 VIN L IOUT TON MAX2 (eq. 8) ) VD ǒVOUT * 1Ǔ h VIN Diode The maximum output current under this maximum on−time control will be achieved at the limits of critical conduction mode and can be calculated from the equation below: IOUT_MAX + 2 VIN2 TON_MAX L (VOUT ) VD) h The diode is the main source of loss in DC−DC converters. The key parameters which affect their efficiency are the forward voltage drop, VD, and the reverse recovery time, trr. The forward voltage drop creates a loss just by having a voltage across the device with a current flowing through it. The reverse recovery time generates a loss when the diode is reverse biased, and the current appears to actually flow backwards through the diode due to the minority carriers being swept from the P−N junction. Care must be taken when choosing a diode. To achieve high efficiency, it is recommended to observe the following rules: 1. Small forward voltage, VD < 0.3 V. 2. Small reverse leakage current. 3. Fast reverse recovery time/switching speed. 4. Rated current larger than peak inductor current, Irated > IPK. 5. Reverse voltage larger than output voltage, Vreverse > VOUT. (eq. 9) The above equation for calculating IOUT_MAX is for DCM mode operation only. The operation can go beyond the critical conduction mode if the current loading further increases above the maximum output current in DCM mode. However, stable operation in continuous conduction mode is hard to achieve. Refer below to the Continuous Conduction Mode section. Maximizing the output current If we target to maximize the output current, the current limit should be chosen to turn off the MOSFET, but this method will result in a larger output ripple voltage. It is critical to make sure that the current limit has been reached before the maximum on−time is met. To ensure this condition is met, the inductance L should be selected according to the following equation: Lt VIN ILIM Input Capacitor The input capacitor stabilizes the input voltage and minimizes peak current ripple from the power source. The capacitor should be connected directly to the inductor pin where the input voltage is applied in order to effectively smooth the input current ripple and voltage due to the inductor current ripple. The input capacitor is also used to decouple the high frequency noise from the VDD supply to the internal control circuit; therefore, the capacitor should be placed close to the VDD pin. For some particular applications, separate decoupling capacitors should be provided and connected directly to the VDD pin for better decoupling effect. A larger input capacitor can better reduce ripple current at the input. By reducing the ripple current at the input, the converter efficiency can be improved. In general, a 4.7 mF to 22 mF ceramic input capacitor is sufficient for most applications. X5R and X7R type ceramic capacitors are recommended due to their good capacitance tolerance and stable temperature behavior. (eq. 10) TON_MAX Since there are 100 ns internal propagation delay between the time the current limit is reached and the time the MOSFET is switched off, the actual peak inductor current can be obtained from the equation below: V IPK + ILIM ) IN L (eq. 11) 100 ns The switching frequency at nominal load is expressed as: FSW(load) + 2 IOUT(VOUT ) VD * h IPK2 L VIN) (eq. 12) Then the maximum output current under the current limit control will be achieved at the limits of critical conduction mode and can be calculated by the equation below: IOUT_MAX + 2 VIN IPK (VOUT ) VD) h (eq. 13) This method can achieve larger maximum output current in DCM mode. Since the current limit is reached in each switching cycle, the inductor current ripple is larger resulting in larger output voltage ripple. Two ceramic capacitors in parallel can be used at the output to keep the output ripple small. Output Capacitor The output capacitor sustains the output voltage by providing the current required by the load and smooths the output ripple voltage. The choice of the output capacitor depends on the application’s requirements for output voltage ripple. Low ESR output capacitors yield better output voltage filtering. Ceramic capacitors are recommended due to their low ESR at high switching frequency and low profile geometry. In general, a 3.3 mF to 22 mF ceramic capacitor should be appropriate for most applications. X5R and X7R type ceramic capacitors are The Continuous Conduction Mode The operation can go beyond the critical conduction mode if the current loading further increases above the maximum output current in DCM mode. However, stable operation in continuous conduction mode is hard to http://onsemi.com 13 NCP1406, NCV1406 recommended due to their good capacitance tolerance and temperature coefficient, while Y5V type ceramic capacitors are not recommended since both their capacitance tolerance and temperature coefficient are too large. The output voltage ripple at nominal load current can be calculated by the following equations: Where IOUT is the nominal load current, COUT is the selected output capacitance, IPK is the peak inductor current, L is the selected inductance, VOUT is the output voltage, VD is the Schottky diode forward voltage, VIN is the input voltage, and ESR is the ESR of the output capacitor. Feedback Resistors To achieve better efficiency at light load, a high impedance feedback resistor divider should be used. Choose the lower resistor R2 value from the range of 10 kW to 200 kW. The value of the upper resistor R1 can then be calculated from the equation below: R1 + R2 OUT * 1Ǔ ǒV1.19 (eq. 15) 1%−tolerance resistors should be used for both R1 and R2 for better VOUT accuracy. Feedforward Capacitor A feedforward capacitor is required to add across the upper feedback resistor to avoid double pulsing or group pulsing at the switching node which will cause larger inductor ripple current and higher output voltage ripple. With adequate feedforward capacitance, evenly distributed single pulses at the switching node can be achieved. The range of the capacitor value is from 5 pF to 200 pF for most applications. For NCP1406, the lower the switching frequency, the larger the feedforward capacitance is needed. For the initial trial value of the feedforward capacitor, the following equation can be used; however, the actual value needs fine tuning: TP1 VIN 1.8 V to 5.0 V L1 8.2 mH C3 R1 VDD 3 Enable TP2 GND CE 1 FB 2 C1 10 mF 2 p R1 PCB layout is very important for switching converter performance. All the converter’s external components should be placed closed to the IC. The schematic, PCB trace layout, and component placement of the step−up DC−DC converter demonstration board are shown in Figures 32 through 35 for PCB layout design reference. The following guidelines should be observed: 1. Grounding Single−point grounding should be used for the output power return ground, the input power return ground, and the device switch ground to reduce noise. The input ground and output ground traces must be thick and short enough for current to flow through. A ground plane should be used to reduce ground bounce. 2. Power Traces Low resistance conducting paths (short and thick traces) should be used for the power carrying traces to reduce power loss so as to improve efficiency (short and thick traces for connecting the inductor L can also reduce stray inductance). The path between C1, L1, D1, and C2 should be kept short. The trace from L to LX pin of the IC should also be kept short. 3. External Feedback Components Feedback resistors R1 and R2, and feedforward capacitor C3 should be located as close to the FB pin as possible to minimize noise picked up by the FB pin. The ground connection of the feedback resistor divider should be connected directly to the GND pin. 4. Input Capacitor The input capacitor should be located close to both the input to the inductor and the VDD pin of the IC. 5. Output Capacitor The output capacitor should be placed close to the output terminals to obtain better smoothing effect on output ripple voltage. (eq. 14) ESR (eq. 16) 1 FSW(load) 20 PCB Layout Guidelines D1 LX 5 NCP1406 VRIPPLE + IPK CFF [ MBR0530LT1 TP3 VOUT 25 V C2 3.3 mF GND 4 R2 TP4 GND Figure 32. Step−Up Converter Demonstration Board Schematic http://onsemi.com 14 NCP1406, NCV1406 Figure 33. Step−Up Converter Demonstration Board Top Layer Component Silkscreen Figure 34. Step−Up Converter Demonstration Board Top Layer Copper Figure 35. Step−Up Converter Demonstration Board Bottom Layer Copper http://onsemi.com 15 NCP1406, NCV1406 Components and Suppliers Output Voltage Parts 15 V C1 Supplier Panasonic TDK C2 Panasonic TDK C3 Panasonic TDK D1 ON Semiconductor L1 Sumida Electric Co. TDK 25 V Part Number Description Website ECJ2FB0J106M Ceramic Capacitor 0805, 10 mF/6.3 V www.panasonic.com C1608X5R0J475MT Ceramic Capacitor 0603, 10 mF/6.3 V www.component.tdk.com ECJ3YB1E475M Ceramic Capacitor 1206, 4.7 mF/25 V www.panasonic.com C3216X5R1E475MT Ceramic Capacitor 1206, 4.7 mF/25 V www.component.tdk.com ECJ1VC1H560K Ceramic Capacitor 0603, 56 pF/50 V www.panasonic.com C1005C0G1H560JT Ceramic Capacitor 0402, 56 pF/50 V www.component.tdk.com MBR0520LT1 Schottky Power Rectifier 20 V/500 mA www.onsemi.com CMD4D11−100MC Inductor 10 mH 1.2 mm Low Profile www.sumida.com VLF4012AT−100MR79 Inductor 10 mH 1.2 mm Low Profile www.component.tdk.com R1 Panasonic ERJ3GEYJ135V Resistor 0603, 1.3 MW www.panasonic.com R2 Panasonic ERJ3GEYJ114V Resistor 0603, 110 kW www.panasonic.com U1 ON Semiconductor NCP1406SNT1 25 V Step−up DC−DC Converter C1 Panasonic ECJ2FB0J106M Ceramic Capacitor 0805, 10 mF/6.3 V www.panasonic.com C1608X5R0J475MT Ceramic Capacitor 0603, 10 mF/6.3 V www.component.tdk.com ECJ5YB1H335M Ceramic Capacitor 1812, 3.3 mF/50 V www.panasonic.com C3225X5R1H475MT Ceramic Capacitor 1206, 3.3 mF/50 V www.component.tdk.com ECJ1VC1H151K Ceramic Capacitor 0603, 150 pF/50 V www.panasonic.com C1005C0G1H151JT Ceramic Capacitor 0402, 150 pF/50 V www.component.tdk.com MBR0530LT1 Schottky Power Rectifier 30 V/500 mA www.onsemi.com TDK C2 Panasonic TDK C3 Panasonic TDK D1 ON Semiconductor L1 Sumida Electric Co. TDK www.onsemi.com CMD4D11−100MC Inductor 10 mH 1.2 mm Low Profile www.sumida.com VLF4012AT−100MR79 Inductor 10 mH 1.2 mm Low Profile www.component.tdk.com R1 Panasonic ERJ3GEYJ225V Resistor 0603, 2.2 MW www.panasonic.com R2 Panasonic ERJ3GEYJ114V Resistor 0603, 110 kW www.panasonic.com U1 ON Semiconductor NCP1406SNT1G 25 V Step−up DC−DC Converter http://onsemi.com 16 www.onsemi.com NCP1406, NCV1406 OTHER APPLICATION CIRCUITS L 8.2 mH C1 2.2 mF VIN 2.0 V to 5.5 V D3 FB 2 VDD 3 D1 LX 5 NCP1406 CE 1 CIN 10 mF D2 VOUT −15 V COUT 4.7 mF 25 V 6.0 mA at VIN = 2.0 V 40 mA at VIN = 5.5 V C3 C2 2.2 mF 1000 pF GND 4 R1 ǒ Ǔ R1 VOUT [ * 1.19 )1 )1 R2 R2 L: CR43−8R2MC, Sumida CIN: ECJ2FB0J106M, Panasonic COUT: ECJ3YB1E475M, Panasonic C1: ECJ2FB1C225K, Panasonic C2: ECJ2FB1C225K, Panasonic C3: ECJ1VC1H102J, Panasonic D1, D2: MBR0520LT1, ON Semiconductor D3: MBR0520LT1 x 2, ON Semiconductor Figure 36. Positive−to−Negative Output Converter for Negative LCD Bias D2 D3 C5 4.7 mF 25 V C4 L1 10 mH C1 10 mF 6.3 V ON 5 pF to 1000 pF CE 1 JP1 OFF C3 R1 FB 2 R2 VDD 3 LX 5 U1 NCP1406 VIN 2.0 V to 5.5 V 2.2 mF GND 4 D1 C2 4.7 mF 25 V ǒ VOUT2 −15 V 2.0 mA at VIN = 2.0 V 5.0 mA at VIN = 2.4 V 10 mA at VIN = 3.0 V VOUT1 15 V 2.0 mA at VIN = 2.0 V 5.0 mA at VIN = 2.4 V 10 mA at VIN = 3.0 V Ǔ R1 VOUT1 + 1.19 )1 R2 VOUT2 [ −VOUT1 ) 0.3 L: CR43−100MC, Sumida C1: ECJ2FB0J106M, Panasonic C2, C5: ECJ3YB1E475M, Panasonic C3: ECJ1VC1H102J, Panasonic C4: ECJ2FB1C225K, Panasonic D1: MBR0520LT1, ON Semiconductor D2, D3: MBR0520LT1 x 2, ON Semiconductor R1: 1.3 MW R2: 110 kW Figure 37. +15 V, −15 V Outputs Converter for LCD Bias Supply http://onsemi.com 17 NCP1406, NCV1406 D4 D5 VOUT2 −7.5 V C7 10 mF 10 mA at VIN = 3.0 V 16 V C5 L1 10 mH C1 10 mF 6.3 V ON C4 2.2 mF 820 pF CE 1 JP1 C3 OFF R1 FB 2 R2 VDD 3 D3 C6 10 mF 16 V D2 LX 5 U1 NCP1406 VIN 3.0 V to 5.5 V 2.2 mF VOUT1 15 V 10 mA at VIN = 3.0 V D1 C2 2.2 mF 16 V GND 4 C9 L: CR43−100MC, Sumida C1: ECJ2FB0J106M, Panasonic C6, C7: ECJ3YB1C106M, Panasonic C3: ECJ1VC1H821J, Panasonic C2, C4, C5: ECJ2FB1C225K, Panasonic D1, D2, D3, D4, D5: MBR0520LT1, ON Semiconductor R1: 1.3 MW R2: 110 kW ǒ Ǔ R1 VOUT1 + 1.19 )1 R2 V VOUT2 [ − OUT1 2 Figure 38. +15 V, −7.5 V Outputs Converter for CCD Supply Circuit TP2 GND L1 4.7 mH C1 22 mF 6.3 V Control Signal D1 JP1 ON CE CE 1 OFF FB 2 VDD 3 R2 100 kW TP3 VOUT ILED 100 mA LX 5 U1 NCP1406 TP1 VIN 3.0 V to 5.5 V U1: NCP1406, ON Semiconductor D1: MBR0520LT1, ON Semiconductor L1: CR43−4R7MC, Sumida C1: ECJHVB0J226M, Panasonic C2: ECJ3YB1C106M, Panasonic LED1, LED2, LED3: LWH1033 (Luxpia) R1: 12 W R2: 100 kW C2 White LED x 3 GND 4 ILED(DC) + 1.19 V R1 Figure 39. White LEDs Driver Circuit http://onsemi.com 18 TP4 GND 10 mF 16 V R1 12 W NCP1406, NCV1406 PACKAGE DIMENSIONS TSOP−5 SN SUFFIX CASE 483−02 ISSUE H D 5X NOTE 5 2X 0.10 T 2X 0.20 T NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. MAXIMUM LEAD THICKNESS INCLUDES LEAD FINISH THICKNESS. MINIMUM LEAD THICKNESS IS THE MINIMUM THICKNESS OF BASE MATERIAL. 4. DIMENSIONS A AND B DO NOT INCLUDE MOLD FLASH, PROTRUSIONS, OR GATE BURRS. 5. OPTIONAL CONSTRUCTION: AN ADDITIONAL TRIMMED LEAD IS ALLOWED IN THIS LOCATION. TRIMMED LEAD NOT TO EXTEND MORE THAN 0.2 FROM BODY. 0.20 C A B M 5 1 4 2 L 3 B S K DETAIL Z G A J C 0.05 DIM A B C D G H J K L M S DETAIL Z SEATING PLANE H T SOLDERING FOOTPRINT* 0.95 0.037 MILLIMETERS MIN MAX 3.00 BSC 1.50 BSC 0.90 1.10 0.25 0.50 0.95 BSC 0.01 0.10 0.10 0.26 0.20 0.60 1.25 1.55 0_ 10 _ 2.50 3.00 1.9 0.074 2.4 0.094 1.0 0.039 0.7 0.028 SCALE 10:1 mm Ǔ ǒinches *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 owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf . SCILLC reserves the right to make changes without further notice to any products herein. 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