NCP5010 Product Preview 500 mW Boost Converter for White LEDs The NCP5010 is a fixed frequency PWM boost converter with integrated rectification optimized for constant current applications such as driving white LEDs. This device features small size, minimal external components and high−efficiency for use in portable applications and is capable of providing up to 500 mW output power to 2−5 series connected white LEDs. A single resistor sets the LED current and the CTRL pin can be pulse width modulated (PWM) to reduce the LED Current. The device can also be configured as a fixed output voltage boost converter for applications such as OLED bias where it is capable of generating voltage up to 20 V. The device includes True−Cutoff circuitry to disconnect the load from the battery when the device is put into standby mode. To protect the device, an output overvoltage protection, and short circuit protection have been incorporated. The NCP5010 is housed in a low profile, space efficient 1.7 x 1.7 mm Flip−Chip package. The device has been optimized for use with small inductors and ceramic capacitors. http://onsemi.com MARKING DIAGRAM A1 1 8−Pin Flip−Chip FC SUFFIX CASE 499AJ DAX A Y WW A1 A2 A3 AGND CTRL • 2.7 to 5.5 V Input Voltage Range • Efficiency: 84% for 5 LED (VF = 3.5 V by LED) at 30 mA and 4.2 V VIN Low Noise 1 MHz PWM DC−DC Converter with Damping Switch Open LED Protection and Short Circuit Protection Serial LEDs Architecture for Uniform Current Matching 1 mA Shutdown Current Facility with True−Cutoff Very Small 8−Pin Flip−Chip 1.7 x 1.7 mm Package NC B1 B3 VIN FB C1 VOUT C2 C3 SW PGND Top View ORDERING INFORMATION See detailed ordering and shipping information in the package dimensions section on page 16 of this data sheet. Typical Applications 90 White LED Backlighting for Small Color LCD Displays Cellular Phones Digital Cameras MP3 Players High Efficiency Step−up Converter VOUT = 5 LED (18 V) 80 70 EFFICIENCY (%) • • • • • = Specific Device Code = Assembly Location = Year = Work Week PIN CONNECTIONS Features • • • • • DAX AYWW VOUT = 3 LED (11 V) 60 50 40 30 20 10 VIN = 4.2 V 0 1 This document contains information on a product under development. ON Semiconductor reserves the right to change or discontinue this product without notice. © Semiconductor Components Industries, LLC, 2005 December, 2005 − Rev. P2 1 10 IOUT (mA) 100 Figure 1. Efficiency vs. Output Current Publication Order Number: NCP5010/D NCP5010 Vbat 2.7 to 5.5 V L1 22 mH FB PGND C1 Cout 1 mF 0805 X5R 25V LED B3 NCP5010 C3 NC 2 to 5 LEDs SW B1 VIN A3 VOUT CTRL AGND A2 A1 ENABLE LED C2 Cin 4.7 mF 0603 X5R 6.3V Rfb 24 Figure 2. Typical Application Circuit PIN FUNCTION DESCRIPTION PIN PIN NAME TYPE DESCRIPTION A1 AGND POWER System ground for the analog circuitry. A high quality ground must be provided to avoid spikes and/ or uncontrolled operations. This pin is to be connected to the PGND pin. B1 VIN POWER Power Supply Input. A ceramic capacitor with a minimum value of 1 mF/6.3 V (X5R or X7R) must be connected to this pin. This capacitor should be placed as close as possible to this pin. In addition, one end of the external inductor is to be connected at this point. C1 VOUT POWER DC−DC converter output. This pin should be directly connected to the load and a low ESR (<30 mW) 1 mF (min) 25 V bypass capacitor. This capacitor is required to smooth the current flowing into the load, thus limiting the noise created by the fast transients present in this circuit. Since this is a current regulated output, this pin has over voltage protection to protect from open load conditions. Care must be taken to avoid EMI through the PCB copper tracks connected to this pin. A2 CTRL INPUT An Active High logic level on this pin enables the device. A built−in pulldown resistor disables the device if the pin is left open. This pin can also be used to control the average current into the load by applying a low frequency PWM signal. If a PWM signal is applied, the frequency should be high enough to avoid optical flicker but be no greater than 1 kHz. C2 SW POWER Power switch connection for inductor. Typical application will use a coil from 10 mH to 22 mH and must be able to handle at least 350 mA. If the desired output power is above 300 mW, the inductor should have a DCR < 1.4 W. A3 NC N/A B3 FB INPUT C3 PGND POWER Not Connected Feedback voltage input used to close the loop by means of a sense resistor connected between the primary LED branch and the ground. The output current tolerance is depends upon the accuracy of this resistor and a ±5% or better accuracy metal film resistor is recommended. An analog dimming signal can be applied to this point to reduce the output current. Please refer to the application section for additional details. Power ground. A high quality ground must be used to avoid spikes and/or uncontrolled operation. Care must be taken to avoid high−density current flow in a limited PCB copper track. This pin is to be connected to the AGND pin. http://onsemi.com 2 NCP5010 MAXIMUM RATINGS Rating Power Supply Voltage (Note 2) Over Voltage Protection Human Body Model (HBM) ESD Rating (Note 3) Machine Model (MM) ESD Rating (Note 3) Digital Input Voltage Digital Input Current Power Dissipation @ TA = +85 °C (Note 6) Thermal Resistance Junction−to−Air 8−Pin Flip−Chip Package Symbol Value Unit VIN 7.0 V VOUT 24 V ESD HBM 2000 V ESD MM 200 V CTRL −0.3 < VIN < Vbat+0.3 1.0 V mA PD Internally Limited mW °C/W RqJA (Note 7) Operating Ambient Temperature Range TA −40 to +85 °C Operating Junction Temperature Range TJ −40 to +125 °C Tstg −65 to +150 °C Storage Temperature Range Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. 1. Maximum electrical ratings are defined as those values beyond which damage to the device may occur at TA = 25°C. 2. According to JEDEC standard JESD22−A108B. 3. This device series contains ESD protection and passes 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. 4. Latchup Current Maximum Rating: ±100 mA per JEDEC standard: JESD78. 5. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A. 6. The thermal shutdown set to 160°C (typical) avoids irreversible damage on the device due to power dissipation. 7. For the 8−Pin Flip−Chip CSP Package, the RqJA is highly dependent on the PCB Heatsink area. For example RqJA can be to 195°C/W with 50 mm total area and also 135°C/W with 500 mm. All the bumps have the same thermal resistance and need to be connected thereby optimizing the power dissipation. http://onsemi.com 3 NCP5010 ELECTRICAL CHARACTERISTICS (Limits apply for TA between −40°C to +85°C and VIN = 3.6 V, unless otherwise noted) Pin Symbol Rating Min Typ Max Unit 5.5 V 420 560 mA 0.6 1.0 W B1 VIN Supply Voltage 2.7 C2 IPEAK_MAX Switch Current Limit 280 NMOS RDS(on) Internal Switch On Resistor FOSC PWM Oscillator Frequency 0.8 1.0 1.2 MHz MDUTY Maximum Duty Cycle 87 90 93 % EFF Efficiency (Note 8) C1 OVPON Overvoltage Clamp Voltage C1 OVPH Overvoltage Clamp Hysteresis C1 POUT Output power (Note 9) VIN = 3.1 V VIN < 3.1 V 20 B3 FBV Feedback Voltage Threshold in Steady State Overtemperature range At 25°C UVLO V 500 300 Minimum Output Current Controlled No Skip Mode (Note 10) B1 V mW IOUT FBVLR % 22 1.0 C1 C1 84 1.0 mV 475 490 Feedback Voltage Line Regulation (Notes 10 and 11) From DC to 100 Hz VIN Undervoltage Lockout Threshold to Enable the Converter Threshold to Disable the Converter mA 500 500 525 510 0.2 0.5 2.4 2.2 2.6 2.4 %/V V 2.2 2.0 B1 UVLOH Undervoltage Lockout Hysteresis 200 mV C1 IOUTSC Short Circuit Output Current 20 mA B1 SCPT Short Circuit Protection Threshold Detected Released B1 C2 % of VIN 35 47 ISTDB Stand by Current, IOUT = 0 mA, CTRL = Low Vbat = 4.2 V IQ Quiescent Current Device Not Switching (BF = VIN) Device Switching (RFB disconnected) 50 67 65 87 2.0 mA 0.4 1.0 A2 VIL Voltage Input Logic Low A2 VIH Voltage Input Logic High 1.2 0.3 A2 RCTRL CTRL Pin Pulldown Resistance 175 8. Efficiency is defined by 100 * (Pout / Pin) at 25°C VIN = 4.2 V with L= Coilcraft DT1608C−223 IOUT = 30 mA, Load = 5 LEDs (VF = 3.5 V per LED) bypassed by 1 mF X5R 9. Guaranteed by design and characterized with L = 22 mH, DCR = 0.7 W max. 10. Load = 4 LEDs (VF = 3.5 V by LED), COUT = 1 mF X5R, L= Coilcraft DT1608C−223. 11. VIN = 3.6 V, Ripple = 0.2 V P−P, IOUT = 15 mA. http://onsemi.com 4 mA V V 350 kW NCP5010 TYPICAL OPERATING CHARACTERISTICS 90 90 80 80 VIN = 2.7 V 70 EFFICIENCY (%) EFFICIENCY (%) Condition: Efficiency = 100 x (Number of LED stacked x VLED x ILED)/PIN VIN = 3.3 V VIN = 4.2 V 60 50 70 VIN = 2.7 V 60 50 0 10 20 30 40 50 60 0 70 10 20 30 40 IOUT (mA) IOUT (mA) 90 90 80 80 VIN = 2.7 V 70 50 60 70 Figure 4. Efficiency vs. Current @ 3 LEDS (10.5 V) L = TDK VLF4012AT−220 EFFICIENCY (%) EFFICIENCY (%) Figure 3. Efficiency vs. Current @ 3 LEDS (10.5 V) L = Coilcraft DT1608C−223 VIN = 3.3 V VIN = 4.2 V 60 VIN = 2.7 V 70 VIN = 3.3 V VIN = 4.2 V 60 50 50 0 10 20 30 40 IOUT (mA) 50 60 0 70 80 80 EFFICIENCY (%) 90 70 20 30 40 50 60 70 Figure 6. Efficiency vs. Current @ 4 LEDS (14 V) L = TDK VLF4012AT−220 90 VIN = 2.7 V 10 IOUT (mA) Figure 5. Efficiency vs. Current @ 4 LEDS (14 V) L = Coilcraft DT1608C−223 EFFICIENCY (%) VIN = 3.3 V VIN = 4.2 V VIN = 3.3 V VIN = 4.2 V 60 VIN = 2.7 V 70 VIN = 3.3 V VIN = 4.2 V 60 50 50 0 10 20 30 40 50 60 0 70 10 20 30 40 50 60 70 IOUT (mA) IOUT (mA) Figure 7. Efficiency vs. Current @ 5 LEDS (17.5 V) L = Coilcraft DT1608C−223 Figure 8. Efficiency vs. Current @ 5 LEDS (17.5 V) L = TDK VLF4012AT−220 http://onsemi.com 5 NCP5010 TYPICAL OPERATING CHARACTERISTICS Condition: Efficiency = 100 x (Number of LED stacked x VLED x ILED)/PIN 90 90 IOUT = 33 mA IOUT = 33 mA 80 80 IOUT = 10 mA 70 IOUT = 23 mA EFFICIENCY (%) EFFICIENCY (%) IOUT = 10 mA 60 50 IOUT = 1 mA 40 70 60 IOUT = 1 mA 50 40 30 30 20 2.5 3.0 3.5 4.0 4.5 5.0 20 2.5 5.5 3.5 4.5 5.0 5.5 Figure 9. Efficiency vs. VIN @ 3 LEDS (10.5 V) L = Coilcraft DT1608C−223 Figure 10. Efficiency vs. VIN @ 4 LEDS (14 V) L = Coilcraft DT1608C−223 510 FEEDBACK VOLTAGE (mV) 80 IOUT = 10 mA IOUT = 23 mA 70 60 IOUT = 1 mA 50 40 30 3.0 3.5 4.0 4.5 5.0 VIN = 3.6 V 505 VIN = 5.5 V 500 VIN = 2.7 V 495 490 −40 5.5 −20 0 20 40 60 80 100 TEMPERATURE (°C) VIN (V) Figure 11. Efficiency vs. VIN @ 5 LEDS (17.5 V) L = Coilcraft DT1608C−223 Figure 12. Feedback Voltage vs. Temperature 1.04 900 VIN = 3.6 V 800 1.02 NMOS RDS(on) (mW) FREQUENCY (MHz) 4.0 VIN (V) IOUT = 28 mA 20 2.5 3.0 VIN (V) 90 EFFICIENCY (%) IOUT = 23 mA VIN = 5.5 V 1.00 0.98 VIN = 2.7 V 0.96 −40 −20 0 VIN = 3.6 V 700 VIN = 2.7 V 600 500 VIN = 5.5 V 400 20 40 60 80 100 300 −40 −20 0 20 40 60 80 TEMPERATURE (°C) TEMPERATURE (°C) Figure 13. Oscillator Frequency vs. Temperature Figure 14. NMOS RDS(on) vs. Temperature http://onsemi.com 6 100 NCP5010 TYPICAL OPERATING CHARACTERISTICS 3 IOUT (mA) 2 3 LEDs 4 LEDs 1 5 LEDs 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VIN (V) Figure 16. Typical VOUT Ripple in OVP Conditions 1 VOUT, 500 mV/div, AC 3 VOUT, 5 V/div, DC Figure 15. Typical Skip Mode Threshold vs. VIN (COUT = 1 mF X5R 25 V) Figure 18. Discontinuous Current Mode (DCM) 1 SW, 5 V/div DC, 4 ILED, 50 mA/div, DC, IOUT = 1 mA Figure 17. Continuous Current Mode (CCM) 1 SW, 5 V/div DC, 4 ILED, 50 mA/div, DC, IOUT = 15 mA Figure 19. Startup for LED Operating, 4 LEDS RBF = 22 W, 1 CTRL, 2 V/div DC, 2 FB, 500 mV/div DC, 4 IL 100 mA/div, T = 100 ms/div Figure 20. Duty Cycle Control Waveforms 1 CTRL, 2 V/div DC, 2 FB, 500 mV/div DC, 4 IL 100 mA/div, T = 1 ms/div http://onsemi.com 7 NCP5010 TYPICAL OPERATING CHARACTERISTICS Figure 21. Typical Ripple for Voltage Operation 1 SW, 10 V/div DC, 2 FB, 500 mV/div DC, 3 VOUT 20 mV/div AC, T = 500 ns/div http://onsemi.com 8 NCP5010 DETAIL OPERATING DESCRIPTION VBat L 2.7 to 5.5 V Cin 1 mF, 6.3 V X5R 0603 22 mH VIN SW B1 C2 A1 AGND − OVP COMP UVLO COMP UVLO + OVP UVLO REF FB VOUT DAMP PROTECTION MAX D C1 NMOS RST DRIVER RAMP COMP SET CLOCK OSC 1 Mhz + IPEAK COMP − 250 k CTRL Cout 1 mF 25 V X5R 0805 SHORT CIRCUIT PROTECTION ONE SHOT IPEAK MAX SC DRIVER − PWM COMP + CTRL FB REF OVP REF THERMAL + − ERROR AMP + B3 − MAX DUTY CYCLE COMP − Up to 22 V + M DUTY REF VIN SENSE CURRENT RFB IPEAK MAX A2 PGND C3 Figure 22. Functional Block Diagram Operation The internal oscillator provides a 1 MHz clock signal to trigger the PWM controller on each rising edge (SET signal) which starts a cycle. During this phase the low side NMOS switch is turned on thus increasing the current through the inductor. The switch current is measured by the SENSE CURRENT and added to the RAMP COMP signal. Then PWM COMP compares the output of the adder and the signal from ERROR AMP. When the comparator threshold is exceeded, the NMOS switch is turned off until the rising edge of the next clock cycle. In addition, there are six functions which can reset the flip−flop logic to switch off the NMOS. The MAX DUTY CYCLE COMP monitors the pulse width and if it exceeds 93% (nom) of the cycle time the switch will be turned off. This limits the switch from being on for more than one cycle. Due to IPEAK COMP, the current through the inductor is monitored and compared with the IPEAK_MAX threshold set at 440 mA (nom). If the current exceeds this value, the controller is will turn off the NMOS switch for the remainder of the cycle. This is a safety function to prevent any excessive current that could overload the inductor and the power stage. The four other safety circuits are SHORT CIRCUIT PROTECTION, OVP, UVLO, and THERMAL PROTECTION. Please refer to the detail in following sections. The loop stability is compensated by the ERROR AMP built in integrator. The gain and the loop bandwidth are fixed internally and provides a phase margin greater than 45° whatever the current supplied. The NCP5010 DC−DC converter is based on a Current Mode PWM architecture which regulates the feedback voltage at 500 mV under normal operating conditions. The boost converter operates in two separate phases (See Figure 23). The first one is TON when the inductor is charged by current from the battery to store up energy, followed by TOFF step where the power is transmitted through the internal rectifier to the load. The capacitor COUT is used to store energy during the TOFF time and to supply current to the load during the TON stage thus constantly powering the load. SW Start Cycle Ipeak 1 MHz IL Ivalley Ton Toff ISW Iout Figure 23. Basic DC−DC Operation http://onsemi.com 9 NCP5010 LED Current Selection 300 The feedback resistor (RFB) determines the average maximum current through the LED string. The control loop regulated the current such that the average voltage at the FB input is 500 mV (nom). For example, should one need a 20 mA output current in the primary branch, RFB should be selected according to the following equation: IPEAK (mA) F RFB + BV + 500 mV + 25 W IOUT 20 mA 150 L = 15 mH V IN = 3.1 V V IN = 4.2 V L = 22 mH 50 10 20 30 40 50 60 70 80 IOUT (mA) Figure 24. Peak Inductor Currents vs. IOUT (mA) @ 3 LEDs, 10.5 V 300 L = 10 mH IPEAK (mA) 250 Inductor Selection 200 150 L = 15 mH To choose the inductor there are three different electrical parameters that need to be considered, the absolute value of the inductor, the saturation current and the DCR. In normal operation, this device is intended to operate in Continuous Conduction Mode (CCM) so the following equation below can be used to calculate the peak current: 100 50 10 I V D IPEAK + OUT ) IN 2LF h(1 * D) L = 22 mH 20 30 V IN = 3.1 V V IN = 4.2 V 40 50 IOUT (mA) 60 70 80 Figure 25. Peak Inductor Currents vs. IOUT (mA) @ 4 LEDs, 14 V In the equation above, VIN is the battery voltage, IOUT is the load current, L the inductor value, F the switching frequency, and the duty cycle D is given by: 300 Ǔ 250 IPEAK (mA) ǒ 200 100 In white LED applications it is desirable to operate the LEDs at a specific operating current as the color will shift as the bias current is changed. As a result of this effect, it is recommended to dim the LED string by a pulse width modulation techniques. A low frequency PWM signal can be applied to the CTRL input and by varying the duty cycle the brightness of the LED can be changed. To avoid any optical flicker, the frequency must be higher than 100 Hz and preferably less than 1 kHz. Due to the soft−start function set at 600 ms (nom) with higher frequency the device remains active but the brightness can decrease. Nevertheless in this case, a dimming control using a filtered PWM signal (See Figure 33) can be used. Also for DC voltage control the same technique is suitable and the filter is takes away. D + 1 * VIN VOUT L = 10 mH 250 h is the global converter efficiency which can vary with load current (see Figure 3 thru Figure 8). A good approximation is to use h = 0.8. Figure 24 − Figure 26 are a graphical representation of the above equations, as a function of the desired IOUT, VIN, and number of LEDs in series (VF = 3.5 V nominal). The curves are limited to an IPEAK_MAX of 300 mA. It is important to analyze this at worst case Vf conditions to ensure that the inductor current rated is high enough such that it not saturate. The recommended inductor value should range between 10 mH and 22 mH. As can be seen from the curves, as the inductor size is reduced, the peak current for a given set of conditions increases along with higher current ripple so it is not possible to deliver maximum output power at lower inductor values. 200 L = 10 mH 150 L = 15 mH L = 22 mH 100 50 10 20 30 V IN = 3.1 V V IN = 4.2 V 40 50 60 70 80 IOUT (mA) Figure 26. Peak Inductor Currents vs. IOUT (mA) @ 5 LEDs, 17.5 V http://onsemi.com 10 NCP5010 Short−Circuit Protection Finally an acceptable DCR must be selected regarding losses in the coil and must be lower than 1.4 W to limit excessive voltage drop. In addition, as DCR is reduced, overall efficiency will improve. Some recommended inductors include but are not limited to: TDK VLF4012AT−220MR51 TDK VLP4612T−220MR34 If VOUT is falls below 50% of VIN then a short−circuit condition is detected. When this event is detected, the PWM circuitry is disabled and the NMOS power switch is not turned on. Power will be supplied to the load through the inductor, rectifier and high side switch. Once VOUT reaches 66% of VIN, then the PWM circuitry is enabled. In normal conditions when the device is enabled by an active high signal on CTRL, the short circuit condition continues until the output capacitor is charged by the limited current up to 66% of VIN. TDK VLP5610T−220MR45 Coilcraft LPO6610−223M Coilcraft DO1605T−223MX Coilcraft DT1608C−223 Capacitor Selection VOUT To minimize the output ripple, a low ESR multi−layer ceramic capacitor type X5R or equivalent should be selected. For LED driver applications a 1 mF (min) 25 V is adequate. The NCP5010 can be operated in a voltage mode configuration (see Figure 34) for applications such as OLED power. Under these conditions, COUT can be increased to 2.2 mF, 25 V or more to reduce the output ripple. The input needs to be bypassed by a X5R or an equivalent low ESR ceramic capacitor near the VIN pin. A 1 mF, 6.3 V is enough for most applications. However, if the connection between VIN and the battery is too long then a 4.7 mF or higher ceramic capacitor may be needed. Some recommended capacitors include but are not limited to: TDK C1608X5R1E105MT TDK C2012X5R1E105MT 2/3 VIN 1/2 VIN Normal Running SC Short−Circuit Condition End of Short−Circuit Occurs Current limited at 20mA Detected Converter Converter in Standby Starts Again T Figure 27. Example of the VOUT Voltage Behavior When Short−Circuit Arises Overvoltage Protection (OVP) If there is an open load condition such as a loose connection to the White LED string, the converter will provide current to the Cout capacitor and the voltage at the output will rise rapidly. This could cause damage to the part if there was not some external clamping Zener clamping circuit. To eliminate the need for these external components, the NCP5010 incorporates an OVP circuit which monitors the output voltage with a resistive divider network and a comparator and voltage reference. If the output reaches 22 V (nominal), the OVP circuit will detect a fault and inhibit PWM operation. This comparator has 1 V of hysteresis so when the load is reconnected and the voltage drops below 21 V, the PWM operation will resume automatically. The 22 V OVP threshold allows the use of 25 V ceramic capacitors for the output filter capacitor. TDK C1608X5R0J105MT TDK C2012X5R1E225MT Murata GRM185R61A105KE36D Murata GRM188R60J475KE19D Murata GRM216R61E105KA12D Damping Switch If the NCP5010 supplies a very light load (< 1 mA), the converter switches enters a Discontinuous Conduction Mode (DCM) and the current through the inductor is no longer continuous (see Figure 18). The converter has a RingKiller circuit which detects entry into DCM mode and turns on the damping switch until the next clock cycle thus minimizing stray oscillations and EMI generation. Undervoltage Lock Out (UVLO) To ensure proper operation under all conditions, the device has a built−in undervoltage lock out (UVLO) circuit. During power−up, the device will remain disabled until the input voltage exceeds 2.4 V nominal. This circuit has 200 mV of hysteresis to provide noise immunity to transient conditions. http://onsemi.com 11 NCP5010 Layout Recommendations As with all switching DC/DC converter, care must be observed to the PCB board layout and component placement. To prevent electromagnetic interference (EMI) problems and reduce voltage ripple of the device any copper trace which see high frequency switching path should be optimized. So the input and output bypass ceramic capacitor, CIN and COUT as depicted Figure 2 must be placed as close as possible the NCP5010 and connected directly between pins and ground plane. In additional, the track connection between the inductor and the switching input, SW pin must be minimized to reduce EMI radiation. Finally it is always good practice to keep way sensitive tracks such as feedback connection from switched signal like SW or VOUT connections. Figure 28 shown an example of optimized PCB layout. Figure 28. Recommended PCB Layout http://onsemi.com 12 NCP5010 TYPICAL APPLICATION CIRCUITS Basic Feedback Figure 29 is a basic application where a regulated courant is drive in a string of LEDs. A 20.8 mA current is fixed by R1 and LEDs are dim with PWM apply on CTRL pin. VBat 2.7 to 5.5 V LED C2 SW C1 LED FB PGND VOUT B3 NCP5010 A1 AGND CTRL C3 A2 PWM VIN B1 Cin 4.7 mF 0603 X5R 6.3 V C2 1 mF 0805 X5R 25 V 2 to 5 LEDs L1 22 mH L1: C1: C2: R1 24 TDK VLF4012AT−220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT Figure 29. Typical Semi−Pulsed Mode of Operation Different Supply need a power delivered for example from an LDO. Care must be observed to have always VBAT above VIN and minimum output voltage range will be VBAT voltage. The NCP5010 can operate from two different supply: One end of the inductor (VBAT) can be directly connected to a battery like 4 cell alkaline or 2 cell Li−Ion. And VIN pin VBat 2.7 to 5.5 V C1 FB LED B3 C3 PGND VOUT C2 1 mF 0805 X5R 25 V 2 to 5 LEDs C2 CTRL NCP5010 LED L1 22 mH SW VIN A2 AGND ENABLE B1 Cin 4.7 mF 0603 X5R 6.3 V A1 Vin R1 24 L1: C1: C2: TDK VLF4012AT−220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT Figure 30. Operate from Different Supply http://onsemi.com 13 NCP5010 Multiple LEDs String two LEDs branches where the constant current is regulated in primary branch and the secondary branch is selected by Q1. The number of LED in each string have to be the same. Since the output voltage in limited at 22 V (nom.), one can arrange the LEDs in 2 or more string. Figure 31 shows VBat 2.7 to 5.5 V C1 FB LED LED C3 B3 AGND A1 NCP5010 C2 1 mF 0805 X5R 25 V LED 2 to 5 LEDs SW VOUT CTRL PGND A2 ENABLE VIN B1 C2 X5R 6.3 V C1 4.7 mF 0603 X5R 6.3 V LED L1 22 mH R1 24 L1: C1: C2: R2 24 PRIMARY BRANCH TDK VLF4012AT−220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT Q1 N ENABLE SECONDARY BRANCH Figure 31. Multiple LED String Application Matched LEDs Branches like this the current in the secondary branch I2 equal the current in primary branch I1. Thank to this current mirror the number of LEDs in secondary branch could be lower or equal than primary one. Should one need to control precisely the current in two LEDs branches the schematic Figure 32 can be used. An dual NPN BC847BD is used to form a current mirror Q1 2.7 to 5.5 V PGND C3 NCP5010 LED C2 1 mF 0805 X5R 25 V 2 to 5 LEDs C1 LED FB B1 VIN SW VOUT CTRL AGND A2 A1 ENABLE C2 X5R 6.3 V C1 4.7 mF 0603 X5R 6.3 V LED L1 22 mH B3 VBat I1 LED I2 NPN Duals Q1 R1 24 R2 24 Q1: L1: C1: C2: ON SEMICONDUCTOR BC847BDW1T1 TDK VLF4012AT−220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT Figure 32. Matched 2 Branches of LEDs http://onsemi.com 14 NCP5010 Analog Dimming Control signal is put from outside to R2 there is no voltage drop across R3 and IOUT = VFB/R4. When the voltage put to R2 is increasing the loop balance output voltage to get always 500 mV to FB pin. Thereby voltage across R4 decreases like this the current in the string of LEDs. When the NCP5010 is in steady state the output voltage is controlled in order to have 500 mV to the feedback input (FB pin). The principle of this schematic is bias by a resistive network R2/R3 the feedback voltage. If not any VBat 2.7 to 5.5 V C1 VOUT FB PGND R3 18 k B3 C3 A1 AGND CTRL NCP5010 2 to 5 LEDs C2 VIN A2 ENABLE SW B1 C1 4.7 mF 0603 X5R 6.3 V R1 10 k C2 1 mF 0805 X5R 25 V LED L1 22 mH LED R4 24 R2 100 k L1: C1: C2: C3: PWM SIGNAL C3 470 nF TDK VLF4012AT−220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT Standard Capacitor Average Network DC VOLTAGE Select Figure 33. Dimming Control Using a Filtered PWM Signal or a DC Voltage DC/DC Boost Application LCD biasing. An external resistive network is connected to sense the output voltage and close the loop. The NCP5010 can be used as DC/DC Boost converter to deliver constant voltage to powering load like OLED or Vout + 0.5 ) R2Ǔ ǒR1 R1 VBat 2.7 to 5.5 V SW FB PGND C1 15 V / 35 mA R 290 k B3 NCP5010 VOUT C3 VIN CTRL AGND A2 A1 ENABLE B1 C1 4.7 mF 0603 X5R 6.3 V C2 L1 22 mH R 10 k C2 2.2 mF 0805 X5R 25 V L1: C1: C2: TDK VLF4012AT−220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E225MT Figure 34. OLED or LCD Bias Supply http://onsemi.com 15 NCP5010 ORDERING INFORMATION Device NCP5010FCT1G Marking Operating Temperature Range Package Shipping† DAX −40°C to +85°C 8−Pin Flip−Chip CSP (Pb−Free) 3000 Tape and 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. Two type of demo boards available: • The NCP5010EVB board which configures the device driving a string of 2−5 White LEDs in series. • The NCP5010BIASEVB board for applications such as powering an OLED panel or LCD biasing. Finally in addition to these demo boards, Application Note “ANDXXXX/D” deals with configuring the NCP5010 with a high side sense resistor. http://onsemi.com 16 NCP5010 PACKAGE DIMENSIONS 8−PIN FLIP−CHIP FC SUFFIX CASE 499AJ−01 ISSUE A −A− 4X NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. COPLANARITY APPLIES TO SPHERICAL CROWNS OF SOLDER BALLS. D 0.10 C −B− PIN 1 INDICATOR E TOP VIEW 0.10 C DIM A A1 A2 D E b e D1 E1 A 0.05 C −C− A2 A1 SIDE VIEW SEATING PLANE MILLIMETERS MIN MAX 0.6 BSC 0.210 0.270 0.330 0.390 1.70 BSC 1.70 BSC 0.290 0.340 0.500 BSC 1.000 BSC 1.000 BSC SOLDERING FOOTPRINT 0.50 0.0197 D1 DIE SIZE MAY VARY e C B 8X b e 0.05 C A B 0.03 C E1 A 1 2 0.50 0.0197 3 BOTTOM VIEW 0.265 0.01 http://onsemi.com 17 SCALE 20:1 mm Ǔ ǒinches NCP5010 ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). 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