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NCP5010 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.
Features http://onsemi.com MARKING DIAGRAM
A1 8-Pin Flip-Chip FC SUFFIX CASE 499AJ DAX G A Y WW DAXG AYWW
1
= Specific Device Code = Pb-Free Package = Assembly Location = Year = Work Week
* 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 This is a Pb-Free Device
PIN CONNECTIONS
A1 A2 A3 NC B3 FB C2 SW C3 PGND
AGND CTRL B1 VIN C1 VOUT
Top View
Typical Applications
ORDERING INFORMATION
See detailed ordering and shipping information in the package dimensions section on page 16 of this data sheet.
White LED Backlighting for Small Color LCD Displays Cellular Phones Digital Cameras MP3 Players High Efficiency Step-up Converter
EFFICIENCY (%)
90 80 70 60 50 40 30 20 10 0 1 10 IOUT (mA) VIN = 4.2 V 100 VOUT = 5 LED (18 V) VOUT = 3 LED (11 V)
Figure 1. Efficiency vs. Output Current
(c) Semiconductor Components Industries, LLC, 2006
1
March, 2006 - Rev. 0
Publication Order Number: NCP5010/D
NCP5010
Vbat 2.7 to 5.5 V
Cin 4.7 mF 0603 X5R 6.3V C2 B1
L1 22 mH
LED
ENABLE
A2 A3
CTRL AGND NC
VOUT PGND
C1 Cout 1 mF 0805 X5R 25V
LED
A1
NCP5010
C3
B3
FB
Rfb 24
Figure 2. Typical Application Circuit
PIN FUNCTION DESCRIPTION
PIN A1 B1 PIN NAME AGND VIN TYPE POWER POWER DESCRIPTION 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. 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. 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. 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. 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. 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.
C1
VOUT
POWER
A2
CTRL
INPUT
C2
SW
POWER
A3 B3
NC FB
N/A INPUT
C3
PGND
POWER
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2 to 5 LEDs
SW
VIN
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 Thermal Resistance Junction-to-Air 8-Pin Flip-Chip Package Operating Ambient Temperature Range Operating Junction Temperature Range Storage Temperature Range Symbol VIN VOUT ESD HBM ESD MM CTRL PD RqJA (Note 6) TA TJ Tstg -40 to +85 -40 to +125 -65 to +150 C C C Value 7.0 24 2000 200 -0.3 < VIN < Vbat+0.3 1.0 Internally Limited Unit V V V V V mA mW C/W
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 = 25C. 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. For the 8-Pin Flip-Chip CSP Package, the RqJA is highly dependent on the PCB Heatsink area. For example RqJA can be to 195C/W with 50 mm total area and also 135C/W with 500 mm. All the bumps have the same thermal resistance and need to be connected thereby optimizing the power dissipation.
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NCP5010
ELECTRICAL CHARACTERISTICS (Limits apply for TA between -40C to +85C and VIN = 3.6 V, unless otherwise noted)
Pin B1 C2 VIN IPEAK_MAX NMOS RDS(on) FOSC MDUTY EFF C1 C1 C1 OVPON OVPH POUT Symbol Supply Voltage Switch Current Limit Internal Switch On Resistor PWM Oscillator Frequency Maximum Duty Cycle Efficiency (Note 7) Overvoltage Clamp Voltage Overvoltage Clamp Hysteresis Output power (Note 8) VIN = 3.1 V VIN < 3.1 V Minimum Output Current Controlled No Skip Mode (Note 9) Feedback Voltage Threshold in Steady State Overtemperature range At 25C Feedback Voltage Line Regulation (Notes 9 and 10) From DC to 100 Hz VIN Undervoltage Lockout measured at 25C Threshold to Enable the Converter Threshold to Disable the Converter Undervoltage Lockout Hysteresis Short Circuit Output Current Short Circuit Protection Threshold Detected Released Stand by Current, IOUT = 0 mA, CTRL = Low Vbat = 4.2 V Quiescent Current Device Not Switching (BF = VIN) Device Switching (RFB disconnected) Voltage Input Logic Low Voltage Input Logic High CTRL Pin Pulldown Resistance 1.2 175 370 0.4 1.0 0.3 V V kW 35 47 2.2 2.0 475 490 500 300 1.0 mA mV 500 500 0.2 2.4 2.2 200 20 50 67 65 87 2.0 mA mA 525 510 %/V 0.5 V 2.6 2.4 mV mA % of VIN 20 0.8 91 Rating Min 2.7 280 420 0.6 1.0 95 84 22 1.0 Typ Max 5.5 560 1.0 1.2 Unit V mA W MHz % % V V mW
C1 B3
IOUT FBV
C1 B1
FBVLR UVLO
B1 C1 B1
UVLOH IOUTSC SCPT
B1 C2
ISTDB IQ
A2 A2 A2
VIL VIH RCTRL
7. Efficiency is defined by 100 * (Pout / Pin) at 25C 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 8. Guaranteed by design and characterized with L = 22 mH, DCR = 0.7 W max. 9. Load = 4 LEDs (VF = 3.5 V by LED), COUT = 1 mF X5R, L= Coilcraft DT1608C-223. 10. VIN = 3.6 V, Ripple = 0.2 V P-P, IOUT = 15 mA.
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NCP5010
TYPICAL OPERATING CHARACTERISTICS
Condition: Efficiency = 100 x (Number of LED stacked x VLED x ILED)/PIN
90 90
80 EFFICIENCY (%) VIN = 3.3 V VIN = 4.2 V EFFICIENCY (%)
80
70
VIN = 2.7 V
70
VIN = 2.7 V
VIN = 3.3 V VIN = 4.2 V
60
60
50 0 10 20 30 40 50 60 70 IOUT (mA)
50 0 10 20 30 40 IOUT (mA) 50 60 70
Figure 3. Efficiency vs. Current @ 3 LEDS (10.5 V) L = Coilcraft DT1608C-223
90
Figure 4. Efficiency vs. Current @ 3 LEDS (10.5 V) L = TDK VLF4012AT-220
90
80 EFFICIENCY (%) VIN = 2.7 V 70 VIN = 3.3 V VIN = 4.2 V EFFICIENCY (%)
80
70
VIN = 2.7 V
VIN = 3.3 V VIN = 4.2 V
60
60
50 0 10 20 30 40 IOUT (mA) 50 60 70
50 0 10 20 30 40 50 60 70 IOUT (mA)
Figure 5. Efficiency vs. Current @ 4 LEDS (14 V) L = Coilcraft DT1608C-223
90
Figure 6. Efficiency vs. Current @ 4 LEDS (14 V) L = TDK VLF4012AT-220
90
80 EFFICIENCY (%) VIN = 2.7 V 70 VIN = 3.3 V VIN = 4.2 V EFFICIENCY (%)
80
70
VIN = 2.7 V
VIN = 3.3 V VIN = 4.2 V
60
60
50 0 10 20 30 40 50 60 70 IOUT (mA)
50 0 10 20 30 40 50 60 70 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
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NCP5010
TYPICAL OPERATING CHARACTERISTICS
Condition: Efficiency = 100 x (Number of LED stacked x VLED x ILED)/PIN
90 IOUT = 33 mA 80 IOUT = 10 mA EFFICIENCY (%) EFFICIENCY (%) 70 60 50 40 30 20 2.5 IOUT = 1 mA IOUT = 23 mA 70 60 50 40 30 20 2.5 IOUT = 1 mA 80 IOUT = 23 mA 90 IOUT = 33 mA IOUT = 10 mA
3.0
3.5
4.0 VIN (V)
4.5
5.0
5.5
3.0
3.5
4.0 VIN (V)
4.5
5.0
5.5
Figure 9. Efficiency vs. VIN @ 3 LEDS (10.5 V) L = Coilcraft DT1608C-223
90 IOUT = 28 mA IOUT = 10 mA IOUT = 23 mA FEEDBACK VOLTAGE (mV) 80 EFFICIENCY (%) 70 60 50 40 30 20 2.5 IOUT = 1 mA 510
Figure 10. Efficiency vs. VIN @ 4 LEDS (14 V) L = Coilcraft DT1608C-223
505
VIN = 3.6 V
500
VIN = 5.5 V VIN = 2.7 V
495
3.0
3.5
4.0 VIN (V)
4.5
5.0
5.5
490 -40
-20
0
20
40
60
80
100
TEMPERATURE (C)
Figure 11. Efficiency vs. VIN @ 5 LEDS (17.5 V) L = Coilcraft DT1608C-223
1.04 VIN = 3.6 V FREQUENCY (MHz) VIN = 5.5 V 1.00 NMOS RDS(on) (mW) 1.02 900 800
Figure 12. Feedback Voltage vs. Temperature
VIN = 3.6 V 700 600 500 VIN = 5.5 V 400 300 -40 VIN = 2.7 V
0.98 VIN = 2.7 V 0.96 -40
-20
0
20
40
60
80
100
-20
0
20
40
60
80
100
TEMPERATURE (C)
TEMPERATURE (C)
Figure 13. Oscillator Frequency vs. Temperature
Figure 14. NMOS RDS(on) vs. Temperature
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NCP5010
TYPICAL OPERATING CHARACTERISTICS
3
2 IOUT (mA)
3 LEDs 1
4 LEDs
5 LEDs 0 2.5
3.0
3.5
4.0 VIN (V)
4.5
5.0
5.5
Figure 15. Typical Skip Mode Threshold vs. VIN (COUT = 1 mF X5R 25 V)
Figure 16. Typical VOUT Ripple in OVP Conditions 1 VOUT, 500 mV/div, AC 3 VOUT, 5 V/div, DC
Figure 17. Continuous Current Mode (CCM) 1 SW, 5 V/div DC, 4 ILED, 50 mA/div, DC, IOUT = 15 mA
Figure 18. Discontinuous Current Mode (DCM) 1 SW, 5 V/div DC, 4 ILED, 50 mA/div, DC, IOUT = 1 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 http://onsemi.com
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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
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
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NCP5010
DETAIL OPERATING DESCRIPTION
VBat 2.7 to 5.5 V Cin 1 mF, 6.3 V X5R 0603
A1
L VIN
B1
22 mH
C2
SW
AGND
- UVLO REF +
UVLO COMP UVLO MAX DUTY CYCLE COMP
- MAX D + - PWM COMP + CTRL
OVP COMP
OVP
+
-
M DUTY REF
THERMAL PROTECTION
OVP REF DAMP
VOUT
C1
FB
B3
FB REF - ERROR AMP +
SC DRIVER
DRIVER
RAMP COMP
SET
SHORT CIRCUIT PROTECTION
ONE SHOT
CLOCK
OSC 1 Mhz
IPEAK MAX
250 k A2
+ IPEAK COMP -
SENSE CURRENT
VIN
RFB
IPEAK MAX
CTRL
PGND
C3
Figure 22. Functional Block Diagram Operation
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.
Start Cycle
SW
1 MHz IL Ton Toff
Ipeak Ivalley
ISW
Iout
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 95% (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.
Figure 23. Basic DC-DC Operation http://onsemi.com
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Up to 22 V
RST
Cout 1 mF 25 V X5R 0805
NMOS
NCP5010
LED Current Selection
300 250 IPEAK (mA) 200 150 100 50 10 L = 15 mH L = 22 mH 20 30 40 50 60 V IN = 3.1 V V IN = 4.2 V 70 80 L = 10 mH
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:
F RFB + BV + 500 mV + 25 W IOUT 20 mA
IPEAK (mA)
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.
Inductor Selection
IOUT (mA)
Figure 24. Peak Inductor Currents vs. IOUT (mA) @ 3 LEDs, 10.5 V
300 L = 10 mH 250 200 150 L = 15 mH 100 50 10 L = 22 mH 20 30 40 50 IOUT (mA) 60 V IN = 3.1 V V IN = 4.2 V 70 80
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:
I VD IPEAK + OUT ) IN 2LF h(1 * D)
Figure 25. Peak Inductor Currents vs. IOUT (mA) @ 4 LEDs, 14 V
300 250 IPEAK (mA) 200 150 100 50 10
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:
D + 1 * VIN VOUT
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.
L = 10 mH L = 15 mH L = 22 mH
V IN = 3.1 V V IN = 4.2 V 40 50 60 70 80
20
30
IOUT (mA)
Figure 26. Peak Inductor Currents vs. IOUT (mA) @ 5 LEDs, 17.5 V
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NCP5010
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 TDK VLP5610T-220MR45 Coilcraft LPO6610-223M Coilcraft DO1605T-223MX Coilcraft DT1608C-223
Capacitor Selection Short-Circuit Protection
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.
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 TDK C1608X5R0J105MT TDK C2012X5R1E225MT Murata GRM185R61A105KE36D Murata GRM188R60J475KE19D Murata GRM216R61E105KA12D
Damping Switch
VOUT
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 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.
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.
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.
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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
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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 L1 22 mH Cin 4.7 mF 0603 X5R 6.3 V A2 LED C2 1 mF 0805 X5R 25 V
PWM
CTRL AGND
VOUT PGND FB
C1
LED L1: C1: C2: TDK VLF4012AT-220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT
A1
NCP5010
C3
B3
R1 24
Figure 29. Typical Semi-Pulsed Mode of Operation Different Supply
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 Vin 2.7 to 5.5 V
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.
2 to 5 LEDs
VIN
SW
C2
B1
L1 22 mH
LED
C2 1 mF 0805 X5R 25 V
ENABLE
A2
CTRL AGND
VOUT PGND FB
C1
LED L1: C1: C2: TDK VLF4012AT-220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT
A1
NCP5010
C3
B3
R1 24
Figure 30. Operate from Different Supply
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2 to 5 LEDs
VIN
SW
C2
B1
Cin 4.7 mF 0603 X5R 6.3 V
NCP5010
Multiple LEDs String
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 L1 22 mH C2
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.
LED
LED
X5R 6.3 V C1 4.7 mF 0603 X5R 6.3 V A2
C2 1 mF 0805 X5R 25 V
ENABLE
CTRL AGND
VOUT PGND FB
C1
LED
2 to 5 LEDs
B1 VIN
SW
LED L1: C1: C2: TDK VLF4012AT-220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT
A1
NCP5010
C3
B3
R1 24 PRIMARY BRANCH ENABLE SECONDARY BRANCH
R2 24 Q1 N
Figure 31. Multiple LED String Application Matched LEDs Branches
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
VBat 2.7 to 5.5 V L1 22 mH C2 LED
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.
LED
X5R 6.3 V C1 4.7 mF 0603 X5R 6.3 V A2
C2 1 mF 0805 X5R 25 V
ENABLE
CTRL AGND
VOUT PGND FB
C1
LED I1
2 to 5 LEDs
B1 VIN
SW
LED I2 Q1 Q1: L1: C1: C2: ON SEMICONDUCTOR BC847BDW1T1 TDK VLF4012AT-220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT NPN Duals
A1
NCP5010
C3
B3
R1 24
R2 24
Figure 32. Matched 2 Branches of LEDs
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NCP5010
Analog Dimming Control
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 L1 22 mH C1 4.7 mF 0603 X5R 6.3 V A2
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.
LED
C2 1 mF 0805 X5R 25 V
ENABLE
CTRL AGND
VOUT PGND FB
C1
R3 18 k R2 100 k
LED
A1
C3
B3
NCP5010 R1 10 k PWM SIGNAL
R4 24 L1: C1: C2: C3: DC VOLTAGE TDK VLF4012AT-220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E105MT Standard Capacitor
C3 470 nF Average Network Select
Figure 33. Dimming Control Using a Filtered PWM Signal or a DC Voltage DC/DC Boost Application
The NCP5010 can be used as DC/DC Boost converter to deliver constant voltage to powering load like OLED or
VBat 2.7 to 5.5 V L1 22 mH C2 B1
LCD biasing. An external resistive network is connected to sense the output voltage and close the loop.
Vout + 0.5 R1 ) R2 R1
C1 4.7 mF 0603 X5R 6.3 V
VIN
SW
ENABLE
A2
CTRL AGND
VOUT PGND FB
C1 R 290 k
15 V / 35 mA C2 2.2 mF 0805 X5R 25 V L1: C1: C2: TDK VLF4012AT-220MR51 TDK C1608X5R0J475MT TDK C2012X5R1E225MT
A1
NCP5010
C3
B3
R 10 k
Figure 34. OLED or LCD Bias Supply
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2 to 5 LEDs
VIN
SW
C2
B1
NCP5010
ORDERING INFORMATION
Device NCP5010FCT1G Marking DAX Operating Temperature Range -40C to +85C Package 8-Pin Flip-Chip CSP (Pb-Free) Shipping 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.
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NCP5010
PACKAGE DIMENSIONS
8-PIN FLIP-CHIP FC SUFFIX CASE 499AJ-01 ISSUE A
-A- D -B-
NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. COPLANARITY APPLIES TO SPHERICAL CROWNS OF SOLDER BALLS. 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
4X
0.10 C
PIN 1 INDICATOR
E
DIM A A1 A2 D E b e D1 E1
0.10 C 0.05 C -C-
SEATING PLANE
TOP VIEW
A
A2 A1 SIDE VIEW D1 e
C B
SOLDERING FOOTPRINT
0.50 0.0197
DIE SIZE MAY VARY
8X
b
e
A 1 2 3
E1 0.50 0.0197
0.05 C A B 0.03 C
BOTTOM VIEW 0.265 0.01
SCALE 20:1
mm inches
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NCP5010
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PUBLICATION ORDERING INFORMATION
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NCP5010/D

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