NCP1403 15 V/50 mA PFM Step-Up DC-DC Converter The NCP1403 is a monolithic PFM step-up DC-DC converter. This device is designed to boost a single Lithium or two cell AA/AAA battery voltage up to 15 V (with internal MOSFET) output for handheld applications. A pullup Chip Enable feature is built with this device to extend battery-operating life. Besides, the device can also be incorporated in step-down, and voltage-inverting configurations. This device is available in space-saving TSOP-5 package. http://onsemi.com 5 1 Features TSOP-5 SN SUFFIX CASE 483 MARKING DIAGRAM AND PIN CONNECTIONS CE 1 FB 2 VDD 3 Typical Applications 5 LX DCEAYWG G •82% Efficiency at VOUT = 15 V, IOUT = 50 mA, VIN = 5.0 V •78% Efficiency at VOUT = 15 V, IOUT = 30 mA, VIN = 3.6 V •Low Operating Current of 19 mA (No Switching) •Low Shutdown Current of 0.3 mA •Low Startup Voltage of 1.3 V Typical at 0 mA •Output Voltage up to 15 V with Built-in 16 V MOSFET Switch •PFM Switching Frequency up to 300 kHz •Chip Enable •Low Profile and Minimum External Parts •Micro Miniature TSOP-5 Package •Pb-Free Package is Available 4 GND (Top View) •LCD Bias •Personal Digital Assistants (PDA) •Digital Still Camera •Handheld Games •Hand-held Instrument DCE =Specific Device Marking A = Assembly Location Y = Year W = Work Week G = Pb-Free Package (Note: Microdot may be in either location) ORDERING INFORMATION Device NCP1403SNT1 NCP1403SNT1G Package Shipping† TSOP-5 3000/Tape & Reel 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 Specifications Brochure, BRD8011/D. © Semiconductor Components Industries, LLC, 2007 May, 2007 - Rev. 6 1 Publication Order Number: NCP1403/D NCP1403 L 47 mH D MBR0520LT1 VOUT 15 V VIN 1.8 V to 5.5 V CE 1 + C1 10 mF LX 5 FB 2 750 pF to 2000 pF CC NCP1403 VDD 3 Enable + GND 4 C2 33 mF RFB1 RFB2 ǒ Ǔ R VOUT + 0.8 FB1 ) 1 RFB2 Figure 1. Typical Step-Up Application Circuit 1 L 22 mH D MBR0520LT1 VIN 2.7 V to 5.5 V CE 1 C1 4.7 mF 10 V FB 2 LX 5 White LED x 4 NCP1403 VDD 3 Enable C2 2.2 mF 16 V ZD GND 4 ILED + 0.8V RS RS Figure 2. Typical Step-Up Application Circuit 2 LX VDD VLx Limit UVLO Soft Start PFM Comparator PFM ON/OFF Timing Control - FB + Driver Vref CE Figure 3. Representative Block Diagram http://onsemi.com 2 GND NCP1403 PIN FUNCTION DESCRIPTIONS 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 PFM comparator inverting input, and is connected to off-chip resistor divider which sets output voltage. 3 VDD Power supply pin for internal circuit. 4 GND Ground pin. 5 LX External inductor connection pin. MAXIMUM RATINGS Rating Symbol Value Unit Power Supply Voltage (Pin 3) 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 16.0 600 -0.3 to 6.0 V mA V CE (Pin 1) Input Voltage Range Input Current Range VCE ICE -0.3 to 6.0 150 V mA 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 °C Operating Junction Temperature Range TJ -40 to +150 °C Storage Temperature Range Tstg -55 to +150 °C Operating Ambient 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 except LX pin. Human Body Model (HBM) "1.5 kV for LX pin. 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. http://onsemi.com 3 NCP1403 ELECTRICAL CHARACTERISTICS (VOUT = 15 V, TA =25°C, for min/max values unless otherwise noted.) Characteristic Symbol Min Typ Max Unit Minimum Off Time (VDD = 3.0 V, VFB = 0 V) toff 0.8 1.3 1.5 ms Maximum On Time (Current not asserted) ton 4.0 6.0 8.4 ms Maximum Duty Cycle DMAX 75 83 91 % Minimum Startup Voltage (IOUT = 0 mA) Vstart - 1.3 1.8 V DVstart - 1.6 - mV/°C Vhold - 1.2 1.7 V tSS 0.5 10 - ms Internal Switch Voltage (Note 4) VLX 0.5 - 16 V LX Pin On-State Sink Current (VLX = 0.4 V, VDD = 3.0 V) ILX 100 130 - mA VLXLIM 0.55 0.75 1.0 V ILKG - 0.1 1.0 mA CE Input Voltage (VDD = 3.0 V, VFB = 0 V) High State, Device Enabled Low State, Device Enabled 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 Enabled (VDD = 5.5 V, VCE = VFB = 0 V) ICE(high) ICE(low) -0.5 -0.5 0 -0.1 0.5 0.5 mA mA Supply Voltage VDD 1.2 - 5.5 V Feedback Voltage VFB 0.76 0.8 0.84 V Feedback Pin Bias Current (VFB = 0.8 V) IFB - 15 30 nA Operating Current 1 (VFB = 0 V, VDD = VCE = 3.0 V) IDD1 - 130 200 mA Operating Current 2 (VDD = VCE = VFB = 3.0 V, Not switching) IDD2 - 19 25 mA Off-state Current (VDD = 5.0 V, VCE = 0 V, internal 100 nA pullup current source) IOFF - 0.3 0.8 mA ON/OFF TIMING CONTROL Minimum Startup Voltage Temperature Coefficient (TA = -40 to +85°C) Minimum Supply Voltage (IOUT = 0 mA) Soft-Start Time LX (PIN 5) Voltage Limit (When VLX reaches VLXLIM, the LX switch is turned off by the LX switch protection circuit) Off-State Leakage Current (VLX = 16 V) CE (PIN 1) TOTAL DEVICE 4. Recommend maximum VOUT up to 15 V. http://onsemi.com 4 NCP1403 TYPICAL CHARACTERISTICS 100 L = 47 mH VOUT = 15 V COUT = 33 mF TA = 25°C Figure 1 16.5 16.0 15.5 Vin = 5.5 V 80 VIN = 5.5 V 15.0 14.5 EFFICIENCY (%) VOUT, OUTPUT VOLTAGE (V) 17.0 3.6 V 1.8 V 2.4 V 4.0 V 5.0 V 3.0 V 14.0 0 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 IOUT, OUTPUT CURRENT (mA) IOUT, OUTPUT CURRENT (mA) Figure 4. Output Voltage versus Output Current (VOUT = 15 V) Figure 5. Efficiency versus Output Current (VOUT = 15 V) 14.0 80 100 L = 47 mH VOUT = 12 V COUT = 33 mF TA = 25°C Figure 1 13.5 13.0 12.5 80 EFFICIENCY (%) VOUT, OUTPUT VOLTAGE (V) L = 47 mH VOUT = 15 V COUT = 33 mF TA = 25°C Figure 1 40 20 VIN = 5.5 V 12.0 5.0 V 11.5 4.0 V 3.6 V 11.0 10.5 5.0 V 4.0 V 13.5 13.0 3.0 V 2.4 V VIN = 5.5 V 5.0 V 4.0 V 3.6 V 1.8 V 60 L = 47 mH VOUT = 12 V COUT = 33 mF TA = 25°C Figure 1 40 3.0 V 2.4 V 1.8 V 20 10.0 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 IOUT, OUTPUT CURRENT (mA) IOUT, OUTPUT CURRENT (mA) Figure 6. Output Voltage versus Output Current (VOUT = 12 V) Figure 7. Efficiency versus Output Current (VOUT = 12 V) 80 12.4 VOUT, OUTPUT VOLTAGE (V) 15.4 VOUT, OUTPUT VOLTAGE (V) 2.4 V 1.8 V 60 3.6 V 3.0 V 15.2 IOUT = 5 mA 15.0 IOUT = 0 mA 14.8 L = 47 mH VOUT = 15 V COUT = 33 mF TA = 25°C Figure 1 14.6 14.4 12.2 IOUT = 5 mA 12.0 IOUT = 0 mA L = 47 mH VOUT = 12 V COUT = 33 mF TA = 25°C Figure 1 11.8 11.6 11.4 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Vin, INPUT VOLTAGE (V) Vin, INPUT VOLTAGE (V) Figure 8. Output Voltage versus Input Voltage (VOUT = 15 V) Figure 9. Output Voltage versus Input Voltage (VOUT = 12 V) http://onsemi.com 5 NCP1403 TYPICAL CHARACTERISTICS 600 800 700 600 500 400 300 200 100 0 2 400 300 200 100 TA = 25°C 3 4 5 6 1 2 3 4 5 6 VIN, INPUT VOLTAGE (V) VIN, INPUT VOLTAGE (V) Figure 10. No Load Input Current versus Input Voltage Figure 11. Current Limit versus Input Voltage 6 VOUT = 15 V TA = 25°C 5 4 3 2 1 1 2 3 4 5 6 5.0 VOUT = 15 V L = 47 mH COUT = 33 mF TA = 25°C Figure 1 4.5 4.0 3.5 VSTART 3.0 VHOLD 2.5 2.0 1.5 1.0 0.5 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 VIN, INPUT VOLTAGE (V) IOUT, OUTPUT CURRENT (mA) Figure 12. Switch-On Resistance versus Input Voltage Figure 13. Startup/Hold Voltage versus Output Current 100 DMAX, MAXIMUM DUTY CYCLE (%) 0.84 VFB, FEEDBACK VOLTAGE (V) 500 0 1 RDS(on), SWITCH-ON RESISTANCE (W) ILIM, CURRENT LIMIT (mA) VOUT = 15 V L = 47 mH D = MBR0520LT1 CIN = 10 mF COUT = 33 mF IOUT = 0 mA TA = 25°C Figure 1 900 VSTART/VHOLD, STARTUP/HOLD VOLTAGE (V) IIN, NO LOAD INPUT CURRENT (mA) 1000 0.82 0.80 0.78 0.76 0.74 -50 -25 0 25 50 75 90 80 70 60 50 -50 100 -25 0 25 50 75 TA, AMBIENT TEMPERATURE(°C) TA, AMBIENT TEMPERATURE (°C) Figure 14. Feedback Voltage versus Ambient Temperature Figure 15. Maximum Duty Cycle versus Ambient Temperature http://onsemi.com 6 100 NCP1403 9 toff, MINIMUM SWITCH OFF TIME (ms) ton, MAXIMUM SWITCH ON TIME (ms) TYPICAL CHARACTERISTICS 8 7 6 5 4 -50 -25 0 25 50 75 100 1 0 -50 -25 0 25 50 75 Figure 17. Minimum Switch Off Time 100 IDD2, OPERATING CURRENT 2 (mA) 25 130 110 VDD = VCE = 3.0 V 90 VFB = 0 V -25 0 25 50 75 23 21 19 VDD = VCE = 3.0 V VFB = 3.0 V NOT SWITCHING 17 15 -50 100 -25 0 25 50 75 TA, AMBIENT TEMPERATURE (°C) TA, AMBIENT TEMPERATURE (°C) Figure 18. Operating Current 1 versus Ambient Temperature Figure 19. Operating Current 2 versus Ambient Temperature ICE(high), CE HIGH INPUT CURRENT (nA) IDD1, OPERATING CURRENT 1 (mA) 2 Figure 16. Maximum Switch On Time 1 Ioff, OFF-STATE CURRENT (mA) 3 TA, AMBIENT TEMPERATURE (°C) 150 0.8 0.6 0.4 VDD = 5.0 V 0.2 0 -50 4 TA, AMBIENT TEMPERATURE (°C) 170 70 -50 5 VCE = 0 V -25 0 25 50 75 100 25 15 5 -5 VDD = 5.5 V -15 -25 -50 VCE = 5.5 V -25 0 25 50 75 TA, AMBIENT TEMPERATURE (°C) TA, AMBIENT TEMPERATURE (°C) Figure 20. Off-State Current versus Ambient Temperature Figure 21. CE High Input Current versus Ambient Temperature http://onsemi.com 7 100 100 NCP1403 TYPICAL CHARACTERISTICS L = 47 mH, CIN = 10 mF, COUT = 33 mF, IOUT = 20 mA 1. VOUT = 15 V, 10 V/div 2. VLX, 10 V/div 3. VIN = 0 V to 3.6 V, 5 V/div L = 47 mH, CIN = 10 mF, COUT = 33 mF, VIN = 3.6 V, IOUT = 20 mA 1. VOUT = 15 V, 10 V/div 2. VLX, 10 V/div 3. VCE = 0 V Figure to 3.3 V,23. 5 V/div Chip Enable Waveforms Figure 22. Startup Waveforms L = 47 mH, CIN = 10 mF, COUT = 33 mF, IOUT = 10 mA 1. VOUT = 15 V (AC Coupled), 100 mV/div 2. VIN = 3.6 V to 5.5 V, 2.0 V/div L = 47 mH, CIN = 10 mF, COUT = 33 mF, VIN = 3.6 V 1. VOUT = 15 V (AC Coupled), 50 mV/div 2. IOUT = 1.0 mA to 15 mA, 10 mA/div Figure 24. Line Transient Response Figure 25. Load Transient Response L = 47 mH, CIN = 10 mF, COUT = 33 mF, VIN = 3.6 V, VOUT = 15 V, IOUT = 10 mA 1. VLX, 5.0 V/div 2. IL, 200 mA/div 3. Vripple, 50 mV/div L = 47 mH, CIN = 10 mF, COUT = 33 mF, VIN = 3.6 V, VOUT = 15 V, IOUT = 30 mA 1. VLX, 5.0 V/div 2. IL, 200 mA/div 3. Vripple, 50 mV/div Figure 26. Operating Waveforms (Medium Load) Figure 27. Operating Waveforms (Heavy Load) http://onsemi.com 8 NCP1403 DETAILED OPERATING DESCRIPTION Operation The NCP1403 is monolithic DC-DC switching converter optimized for single Lithium or two cells AA/AAA size batteries powered portable products. The NCP1403 device consists of startup circuit, chip enable circuit, PFM comparator, voltage reference, PFM on/off timing control circuit, driver, current limit circuit, and open-drain MOSFET switch. The device operating current is typically 130 mA, and can be further reduced to about 0.3 mA when the chip is disabled (VCE < 0.3 V). The operation of NCP1403 can be best understood by referring to the block diagram and typical application circuit 1 in Figures 3 and 1. 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 control and driver circuit turns on the N-Channel MOSFET switch and the current ramps up in the inductor. The switch will remain on for the maximum on-time, 6.0 ms, or until the current limit is reached, whichever occurs first. The MOSFET switch is then turned off and energy stored in the inductor will be discharged to the output capacitor and load through the Schottky diode. The MOSFET switch will be turned off for at least the minimum off-time, 1.3 ms, and will remain off if the feedback voltage is higher than the reference voltage and output capacitor will be discharged to sustain the output current, until the feedback voltage is again lower than reference voltage. This switching cycle is then repeated to attain voltage regulation. Voltage Reference and Output Voltage The internal voltage reference is trimmed to 0.8 V at an accuracy of ±5.0%. 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 connected an external resistor voltage divider from the VOUT to the FB pin. With the internal 16 V MOSFET switch, the output voltage can be set between VIN to 15 V. LX Limit The LX Limit is a current limit feature which is achieved by monitoring the voltage at the LX pin during the MOSFET switch turn-on period. When the switch is turned on, current ramps up in the inductor, and the voltage at the LX pin will increase according to the Ohm's Law due to the On-state resistance of the MOSFET. When the VLX is greater than 0.75 V, the switch will be turned off. With the current limit circuit, saturation of inductor is prevented and output voltage overshoot during startup can also be minimized. N-Channel MOSFET Switch The NCP1403 is built-in with a 16 V open drain N-Channel MOSFET switch which allows high output voltage up to 15 V to be generated from simple step-up topology. Enable / Disable Operation The NCP1403 offers IC shut-down mode by the chip enable pin (CE pin) to reduce current consumption. An internal 100 nA pullup current source tied the CE pin to OUT pin by default i.e. user can float the pin CE for permanent “ON”. When voltage at pin CE is equal to or greater than 0.9 V, the chip will be enabled, which means the device is in normal operation. When voltage at pin CE is less than 0.3 V, the chip is disabled, which means IC is shutdown. During shutdown, the IC supply current reduces to 0.3 mA and 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 to one diode forward voltage drop below the input voltage. Soft Start There is a soft start circuit in NCP1403. When power is applied to the device, the soft start circuit pumps up the output voltage to approximately 1.5 V at a fixed duty cycle, the level at which the converter can operate normally. With the soft start circuit, the output voltage overshoot is minimized and the startup capability with heavy loads is also improved. ON/OFF Timing Control The maximum on-time is typically 6.0 ms, whereas, the minimum off-time is typically 1.3 ms. Owing to the current limit circuit, the on-time can be shorter. The switching frequency can be up to 300 kHz. http://onsemi.com 9 NCP1403 APPLICATIONS CIRCUIT INFORMATION For step-up converter operates in DCM only, the External Component Selection Inductor maximum output current can be calculated from the The NCP1403 is designed to work well with a range of equation below: inductance values, the actual inductance value depends on (ILIM) 2L IOUT(MAX) + the specific application, output current, efficiency, and I L 2(VOUT ) VD * VIN)ǒǒVLIM*V Ǔ ) toff(MIN)Ǔ output ripple voltage. For step up conversion, the device IN S works well with inductance ranging from 22 mH to 47 mH. For step-up converter operates in CCM, the maximum Inductor with small DCR, usually less than 1.0 W, should be output current can be calculated from the equation below: used to minimize loss. It is necessary to choose an inductor (VOUT ) VD * VIN) toff(MIN) (VIN * VS) IOUT(MAX) + ILIM * @ with saturation current greater than the peak switching 2L (VOUT ) VD * VS) current in the application. Diode If 22 mH inductance is used, lower profile surface mount The diode is the main source of loss in DC-DC converters. inductor can be selected for the same current rating. The most importance parameters which affect their Moreover, it permits the converter to switch at higher efficiency are the forward voltage drop, VF, and the reverse frequency up to 300 kHz since the inductor current will ramp recovery time, trr. The forward voltage drop creates a loss up faster and hit the current limit at a shorter time for smaller just by having a voltage across the device while a current inductance value. However, current output are slightly flowing through it. The reverse recovery time generates a lower because the off-time is limited by the minimum loss when the diode is reverse biased, and the current appears off-time. If 47 mH inductance is selected, higher efficiency to actually flow backwards through the diode due to the and output current capability are achieved, but the converter minority carriers being swept from the P-N junction. A will switch at a lower frequency and the inductor size will be Schottky diode with the following characteristics is slightly larger for the same current rating. recommended: For lower inductance value, the inductor current 1. Small forward voltage, VF < 0.3 V ramp-down time will be shorter than the minimum off-time. 2. Small reverse leakage current Consequently, the converter can only operate in 3. Fast reverse recovery time / switching speed discontinuous conduction mode and lower output current 4. Rated current larger than peak inductor current, can be generated. For higher inductance value, if the Irated > IPK inductance is sufficiently large, the maximum on-time will 5. Reverse voltage larger than output voltage, expire before the current limit is reached. As a result, the Vreverse > VOUT available output power and output current are reduced. Input Capacitor Besides, instability may occur when operation enters CCM. The input capacitor can stabilize the input voltage and To ensure the current limit is reached before the maximum minimize peak current ripple from the source. The value of on-time expires, L can be selected according to the the capacitor depends on the impedance of the input source inequality below: used. Small ESR (Equivalent Series Resistance) Tantalum (VIN * VS) or ceramic capacitor with value of 10 mF should be suitable. Lv @t ǒ ILIM on(MAX) Ǔ Output Capacitor The output capacitor is used for sustaining the output voltage when no current is delivering from the input, and smoothing the ripple voltage. Low ESR Tantalum capacitor should be used to reduce output ripple voltage since the output ripple voltage is dominated by the ESR value of the Tantalum capacitor. In general, a 22 mF to 47ĂmF low ESR (0.2 W to 0.4 W) Tantalum capacitor should be appropriate. The output ripple voltage can be approximately given by the following equation: where VS = 0.75 V which is the MOSFET saturation voltage, and ILIM is the current limit which can be referred to in Figure 11, and ton(MAX) = 6.0 ms. If the above condition is satisfied, IPK = ILIM; where IPK is the peak inductor current. Then, step-up converter with inductor satisfy the following condition will operate in DCM only, ILIM @ L v toff(MIN) (VOUT ) VD * VIN) Vripple [ (IPK * IOUT) @ ESR If the IPK = ILIM, step-up converter with inductor satisfy the following condition will operate in CCM at maximum output current, Feedback Resistors Choose the RFB2 value from the range 10 kW to 200 kW for positive output voltage. The value of RFB1 can then be calculated from the equation below: ILIM @ L u toff(MIN) (VOUT ) VD * VIN) ǒVOUT * 1Ǔ 0.8 where VD is the Schottky diode forward voltage drop, toff(MIN) = 1.3 ms. RFB1 + RFB2 1% tolerance resistors should be used for both RFB1 and RFB2 for better VOUT accuracy. http://onsemi.com 10 NCP1403 Output Voltage Higher than 15 V White LED Driver NCP1403 can be used to generate output voltage higher than 15 V by adding an external high voltage N-Channel MOSFET in series with the internal MOSFET switch as shown in Figure 33. The drain-to-source breakdown voltage of the external MOSFET must be at least 1V higher than the output voltage. The diode D1 helps the external MOSFET to turn off and ensures that most of the voltage across the external MOSFET during the switch-off period. Since the high voltage external MOSFET is in series with the internal MOSFET, higher break down voltage is achieved but the current capability is not increased. There is an alternative application circuit shown in Figure 35 which can output voltage up to 30 V. For this circuit, a diode-capacitor charge-pump voltage doubler constructed by D2, D3 and C1 is added. During the internal MOSFET switch-on time, the LX pin is shorted to ground and D2 will charge up C1 to the stepped up voltage at the cathode of D1. During the MOSFET switch-off time, the voltage at VOUT will be almost equal to the double of the voltage at the cathode of D1. The VOUT is monitored by the FB pin via the resistor divider and can be set by the resistor values. Since the maximum voltage at the cathode of D1 is 15V, the maximum VOUT is 30 V. The value of C1 can be in the range of 0.47 mF to 2.2 mF. The NCP1403 can be used as a constant current LED driver which can drive up to 4 white LEDs in series as shown in Figure 2. The LED current can be set by the resistance value of RS. The desired LED current can be calculated by the equation below: Negative Voltage Generation VMAX is the maximum voltage of the control signal, VD is the diode forward voltage, ILED(MAX) is the maximum LED current and ILED(MIN) is the minimum LED current. If a PWM control signal is used, the signal frequency from 4 kHz to 40 kHz can be applied. In case the LEDs fail, the feedback voltage will become zero. The NCP1403 will then switch at maximum duty cycle and result in a high output voltage which will cause the LX pin voltage to exceed its maximum rating. A Zener diode can be added across the output and FB pin to limit the voltage at the LX pin. The Zener voltage should be higher than the total forward voltage of the LED string. ILED + 0.8 RS Moreover, the brightness of the LEDs can be adjusted by a DC voltage or a PWM signal with an additional circuit illustrated below: To FB Pin R1 R2 DC/PWM Signal C1 0.1 mF To LED D2 100 k RS C2 820 pF GND With this additional circuit, the maximum LED current is set by the above equation. The value of R2 can be obtained by the following equation: R2 + The NCP1403 can be used to produce a negative voltage output by adding a diode-capacitor charge-pump circuit (D2, D3, and C1) to the LX pin as shown in Figure 32. The feedback voltage resistor divider is still connected to the positive output to monitor the positive output voltage and a small value capacitor is used at C2. When the internal MOSFET switches off, the voltage at the LX pin charges up the capacitor through diode D2. When the MOSFET switches on, the capacitor C1 is effectively connected like a reversed battery and C1 discharges the stored charges through the Rds(on) of the internal MOSFET and D3 to charge up COUT and builds up a negative voltage at VOUT. Since the negative voltage output is not directly monitored by the NCP1403, the output load regulation of the negative output is not as good as the standard positive output circuit. The resistance values of the resistors of the voltage divider can be one-tenth of those used in the positive output circuit in order to improve the regulation at light load. For the application circuit in Figure 36, it is actually the combination of the application circuits in Figures 32 and 33. ǒ VMAX * VD * 0.8 (ILED(MAX)*ILED(MIN))RS R1 Ǔ PCB Layout Hints The schematic, PCB trace layout, and component placement of the step-up DC-DC converter demonstration board are shown in Figure 28 to Figure 31 for PCB layout design reference. Grounding One 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. Step-Down Converter NCP1403 can be configured as a simple step-down converter by using the open-drain LX pin to drive an external P-Channel MOSFET as shown in Figure 34. The resistor RGS is used to switch off the P-Channel MOSFET during the switch-off period. Too small resistance value should not be used for RGS, otherwise, the efficiency will be reduced. http://onsemi.com 11 NCP1403 Power Signal Traces External Feedback Resistors Low resistance conducting paths 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). Besides, the length and area of all the traces with connection to the LX pin should be minimized. e.g., short and thick traces listed below should be used in the PCB: 1. Trace from VIN to L 2. Trace from L to LX pin of the IC 3. Trace from L to anode pin of Schottky diode 4. Trace from cathode pin of Schottky diode to VOUT. Feedback resistors 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. Input Capacitor The input capacitor should be located close to both the VIN to the inductor and the VDD pin of the IC. Output Capacitor The output capacitor should be placed close to the output terminals to obtain better smoothing effect on output ripple voltage. L1 TP1 VIN 1.8 V to 5.0 V 47 mH D1 TP3 VOUT 15 V MBR0520LT1 + C1 10 mF CE 1 C3 R1 Enable R2 FB 2 LX 5 + C2 33 mF NCP1403 VDD 3 GND 4 TP2 GND Figure 28. Step-Up Converter Demonstration Board Schematic http://onsemi.com 12 TP4 GND NCP1403 Figure 29. Step-Up Converter Demonstration Board Top Layer Copper Figure 30. Step-Up Converter Demonstration Board Bottom Layer Copper Figure 31. Step-Up Converter Demonstration Board Top Layer Component Silkscreen http://onsemi.com 13 NCP1403 Components Supplier Parts Supplier Part Number Description Phone L1 Sumida Electric Co. Ltd. CD43-470KC Inductor 47 mH (852) 2880-6688 D1 ON Semiconductor MBR0520LT1 Schottky Power Rectifier (852) 2689-0088 C1 Kemet Electronics Corp. T494A106K010AS Low ESR Tantalum Capacitor 10 mF/10 V (852) 2305-1168 C2 Kemet Electronics Corp. T494C336K016AS Low ESR Tantalum Capacitor 33 mF/16 V (852) 2305-1168 OTHER APPLICATIONS L 47 mH C1 10 mF MBR0520LT1 x 2 2.2 mF C3 VIN 2.0 V to 5.5 V D3 D1 CE 1 + D2 MBR0520LT1 LX 5 + CC FB 2 3000 pF NCP1403 VDD 3 VOUT -15 V 6 mA at VIN = 2.0 V C4 40 mA at VIN = 5.5 V 33 mF 25 V C2 0.1 mF GND 6 RFB1 RFB2 L: CD43-470KC, Sumida C1: T494A106K010AS, Kemet C2: EMK107BJ104MA, Taiyo Yuden C3: GMK316F225ZG, Taiyo Yuden C4: T494D336K025AS, Kemet D1, D2, D3: MBR0520LT1, ON Semiconductor ǒ Ǔ R VOUT [ * 0.8 FB1 ) 1 ) 1 RFB2 Figure 32. Positive-to-Negative Output Converter for Negative LCD Bias L 47 mH VIN 3.0 V to 5.5 V C1 10 mF 10 V D1 MBR0530T1 MGSF1N03T1 / NTHS5402T1 Q1 + CE 1 FB 2 VDD 3 LX 5 CC 750 pF to 2000 pF D2 RFB1 VOUT Up to 29 V + 6 mA at VIN = 3.0 V C2 35 mA at VIN = 5.5 V 22 mF 35 V MMSD914T1 NCP1403 RFB2 GND 6 ǒ Ǔ R VOUT + 0.8 FB1 ) 1 RFB2 L: CD43-470KC, Sumida C1: T494A106K010AS, Kemet C2: T494D226K035AS, Kemet Q1: MGSF1N03T1, ON Semiconductor NTHS5402T1, ON Semiconductor D1: MBR0530T1, ON Semiconductor D2: MMSD914T1, ON Semiconductor Figure 33. Step-Up DC-DC Converter with 29 V Output Voltage http://onsemi.com 14 NCP1403 Q1 VIN 2.2 V to 4.2 V C1 22 mF 10 V RGS 820 LX 5 + CE 1 FB 2 L 100 mH VOUT 1.6 V 68 mF + 200 mA 6V C2 at VIN = RFB1 2.2 V CC D1 750 pF to 2000 pF MBR0520LT1 NCP1403 RFB2 VDD 3 L: C1: C2: Q1: D1: MGSF1P02LT1 GND 6 ǒ Ǔ R VOUT + 0.8 FB1 ) 1 RFB2 CD43-101KC, Sumida T494C226K010AS, Kemet T494D686K006AS, Kemet MGSF1P02ELT1, ON Semiconductor MBR0520LT1, ON Semiconductor Figure 34. Step-down DC-DC Converter with 1.6 V Output Voltage for DSP Circuit L 47 mH C3 2.2 mF D3 MBR0520LT1 VIN 1.8 V to 5.5 V C1 10 mF 10 V + CE 1 CC RFB1 750 pF to 2000 pF FB 2 VDD 3 D2 MBR0520LT1 LX 5 U1 D1 MBR0520LT1 NCP1403 GND 6 + C4 10 mF 20 V + VOUT 30 V 2 mA at VIN = 1.8 V 35 mA at VIN = 5.5 V C2 10 mF 20 V RFB2 ǒ Ǔ R VOUT + 0.8 FB1 ) 1 RFB2 L: CD43-470KC, Sumida C1: T494A106K010AS, Kemet C2, C4: T494D106K020AS, Kemet C3: GMK316F225ZG, Taiyo Yuden D1, D2, D3: MBR0520LT1, ON Semiconductor Figure 35. Step-Up DC-DC Converter with 30 V Output Voltage http://onsemi.com 15 NCP1403 D3 D4 MBR0530T1 x 2 VOUT -28 V L + 47 mH C3 D2 2.2 mF / 50 V VIN 3.5 V to 5.0 V + MMSD914T1 + C1 10 mF 10 V CE 1 CC RFB1 750 pF to 2000 pF FB 2 U1 C4 22 mF 35 V 9 mA at VIN = 3.3 V 20 mA at VIN = 5.0 V C2 1 mF 50 V Q1 LX MGSF1N03T1 5 / NTHS5402T1 D1 MMSD914T1 NCP1403 VDD 3 ǒ GND 6 Ǔ R VOUT [ * 0.8 FB1 ) 1 ) 1 RFB2 RFB2 L: C1: C2: C3: C4: Q1: CD43-470KC, Sumida T494A106K010AS, Kemet UMK212F105ZG, Taiyo Yuden GMK316F225ZG, Taiyo Yuden T494D226K035AS, Kemet MGSF1N03T1, ON Semiconductor/ NTHS5402T1, ON Semiconductor D1, D2: MMSD914T1, ON Semiconductor D3, D4: MBR0530T1, ON Semiconductor Figure 36. Voltage Inverting DC-DC Converter with -28 V Output Voltage MBR0520LT1 D2 MBR0520LT1 D3 VOUT2 -15 V 2 mA at VIN = 1.8 V 22 mF 5 mA at VIN = 2.4 V 20 V 10 mA at VIN = 3.0 V C5 C4 2.2 mF L1 47 mH + VIN 1.8 V to 5.5 V C1 10 mF 10 V ON 750 pF to 2000 pF CE 1 JPI OFF C3 + D1 MBR0520LT1 R1 R2 FB 2 VDD 3 U1 LX 5 NCP1403 ǒ GND 6 Ǔ R VOUT1 + 0.8 FB1 ) 1 RFB2 VOUT2 [ * VOUT1 ) 0.3 L1: CD43-470KC, Sumida C1: T494A106K010AS, Kemet C2, C5: T494C226K020AS, Kemet C3: UMK107B102KZ, Taiyo Yuden C4: TMK316BJ225ML, Taiyo Yuden D1, D2, D3: MBR0520LT1, ON Semiconductor R1: 390 kW Figure 37. +15 V, -15 V Outputs Converter for LCD Bias Supply R2: 22 kW http://onsemi.com 16 C2 22 mF 20 V VOUT1 15 V 2 mA at VIN = 1.8 V 5 mA at VIN = 2.4 V 10 mA at VIN = 3.0 V NCP1403 MBR0520LT1 D3 MBR0520LT1 D4 C7 C5 2.2 mF L1 47 mH MBR0520LT1 + D5 C4 2.2 mF VIN 1.8 V to 5.5 V C1 10 mF 10 V + ON CE 1 C3 R1 R2 FB 2 VDD 3 U1 LX 5 C6 22 mF 20 V MBR0520LT1 JPI OFF + D2 750 pF to 2000 pF 22 mF 20 V + C2 D1 MBR0520LT1 10 mF 10 V NCP1403 GND 6 ǒ Ǔ R VOUT1 + 0.8 FB1 ) 1 RFB2 L1: CD43-470KC, Sumida V VOUT2 [ * OUT1 C1, C2: T494A106K010AS, Kemet 2 C3: UMK107B102KZ, Taiyo Yuden C4, C5: TMK316BJ225ML, Taiyo Yuden C6, C7: T494C226K020AS, Kemet D1, D2, D3, D4, D5: MBR0520LT1, ON Semiconductor R1: 390 kW Figure 38. +15 V, -7.5 V Outputs Converter for CCD Supply Circuit R2: 22 kW http://onsemi.com 17 VOUT2 -7.5 V 5 mA at VIN = 3.0 V VOUT1 15 V 20 mA at VIN = 3.0 V NCP1403 PACKAGE DIMENSIONS TSOP-5 SN SUFFIX CASE 483-02 ISSUE G NOTE 5 2X 0.10 T 2X 0.20 T D 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. 5X 0.20 C A B M 5 1 4 2 3 B S K L DETAIL Z G A J C 0.05 SEATING PLANE H 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 DIM A B C D G H J K L M S DETAIL Z T SOLDERING FOOTPRINT* 0.95 0.037 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. The product described herein (NCP1403), may be covered by the following U.S. patents: 6,518,834. There may be other patents pending. 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. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer's technical experts. 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