NXA4001. NEXT Lab. Semiconductor Development Group. General Description. Feature. Application. 2MHz, 1.5A Boost Type Flash LED Driver

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1 NEXT Lab Semiconductor Development Group NXA4001 2MHz, 1.5A Boost Type Flash LED Driver General Description The NXA4001 is a high-efficiency, boost converter capable of delivering up to 1.5A maximum output current. It maintains output current regulation by switching the internal high-side and low-side switch transistors, the transistor switches are pulse-width modulated at a fixed frequency of 2MHz. NXA4001 contains OCP (Over Current Protection), OTP (Over Temperature Protection), Short Circuit Protection and OVP (Over Voltage Protection). OVP is function to protect the device in the event of an output open-circuit condition and input voltage over 5.3V in this device. The shutdown feature reduces quiescent current to less than 1uA. The NXA4001 is available in 9P-WLCSP package and operates over the -40 to 150 temperature range. Feature Operating Voltage Range, from 2.5V to 5.3V Up to 1.5A regulated output current Up to 90% efficiency 2MHz Switching Frequency Single Channel Flash Output Single Resistor Set Flash and Torch Mode Current Soft-Start OVP, OCP, OTP, Short Circuit Protection -40 C to C Temperature Range Package : 9P-WLCSP Application LED Photo Flash & Torch Camera Enabled on Mobile devices Cellular Phones & Smart Phones Digital Cameras - 1 -

2 Block Diagram VCC POR OSC Reference OTP,OVP,OCP UVLO VOUT Logic & PWM Control Short Protection PG Driver NG Driver LX Serial Interface Control PGND RSET Soft Start & Dimming NMOS Current Source FLED FGND AGND Typical Application Circuit V 2.2uF 1uH PGND LX VOUT VCC FLED AGND RSET 2.2uF Serial Interface 15KΩ - 2 -

3 Pin Assignments C B A 1 PGND LX VOUT 2 VCC FLED 3 AGND RSET <9-WLP Bottom view> Pin Description Pin No. Pin Name I/O Description A1 VOUT O Power Output of the Boost Converter. Connect a 2.2uF or larger ceramic Capacitor from VOUT to ground as possible as close to the NXA4001. Connect VOUT to the anode of the Flash LED. A2 FLED O Flash current output. Connect the cathode of flash LED to FELD. A3 RSET I Output current set pin. B1 LX - Boost converter switching node. Connect a 1uH inductor between LX and VCC. B2 VCC Power Power input. Connect VCC to the input power supply voltage. Connect a 2.2uF or Larger ceramic capacitor from VCC to ground as close as possible to the NXA4001. B3 FGND GND Flash ground pin. Connect FGND to PGND, and AGND at a single point as possible as close to the NXA4001. C1 PGND GND Power ground. C2 lash Mode and Torch Mode(Dimming) control data. (Pull down) C3 lash inhibit Data.(Pull Down) - 3 -

4 Maximum Absolute Rating Parameter Symbol Value Unit Supply Input Voltage V CCMAX -0.3 ~ 6.0 V Serial Interface Input Voltage V fen -0.3 ~ 6.0 V Operating Temperature T jopr -40 ~ 150 Electrical Characteristics Unless otherwise noted, V CC = 3.6V, C IN = 2.2uF, C OUT = 2.2uF, LX = 1uH, RSET = 15KΩ, Ta = 27 Characteristics Symbol Conditions Min Typ Max unit Input Voltage Range V IN V Under Voltage Lock Out V UVLO 2.2 V Shutdown Current I SHDI 1 ua Supply Current I IN FLED = Open 600 ua Output Current, Flash Mode 1.5 A Output Current, Torch Mode I T(max) Max Current 600 ma I T(min) Min Current 28 ma Torch Current Accuracy I T(ACC) ±5 % Switching Frequency F osc T A = 27 Boost Mode MHz Minimum Duty Cycle D min Boost Mode 3 % Maximum Duty Cycle D max Boost Mode 70 % Over Voltage Protection(VIN) V OVP(IN) 5.3 V Over Voltage Protection(VOUT) V OVP(OUT) 5.1 Over Temperature Protection V OTP 150 LED Sense Voltage V FLED Boost Mode 200 mv RSET Voltage V RSET 500 mv / Input High Threshold V (H) 1.4 V V (H) / Input Low Threshold V (L) 0.9 V V (L) PMOS On Resistance R DSP VCC=VGS=3.6V mω NMOS On Resistance R DSN VCC=VGS=3.6V mω Flash On Time T Flon Max time 2 s - 4 -

5 Typical Characteristics Efficiency (500mA,1A,1.5A) Efficiency (60mA,100mA,300mA) 100% 500mA, Vled = % 60mA, Vled = A, Vled = mA, Vled = % 1.5A, Vled = % 300mA, Vled =2.71 Efficiency(%) 80% 70% 60% Efficiency(%) 80% 70% 60% 50% 50% 40% Input voltage(v) 40% Input voltage(v) Boost mode Switching Frequency Supply Current ( = 1.5A) (V = 3.6V, Minimum Current mode) Switching Frequency(MHz) Supply Current(uA) Input voltage(v) Input voltage(v) Torch mode LED current Accuracy (I T(MAX) = 600mA) Output Current(mA) Input voltage(v) - 5 -

6 Flash mode Switching Waveform Torch mode Switching Waveform ( = 1.5A, V CC = 4V) (I T(MAX) = 600mA, V CC = 3V) Flash mode Turn On Characteristic Torch mode Turn On Characteristic ( = 1.5A, V CC = 3.6V) (I T(MAX) = 600mA, V CC = 3.6V) - 6 -

7 Application Note Flash Mode - Flash Mode operates when the state of pin become High from Low (Rising) - The maximum flash current in NXA4001 is set by an external resistor, R SET, which sets the flash current and the maximum movie-mode current. - Flash mode operation is controlled entirely by the serial interface via the pin and pin. - If the pin low state is higher than 500us, it cannot use in the Flash Mode. - Flash mode can be operated at a maximum of 2 seconds. Flash Mode Command Normal mode when don t using Auto Reset after 2 seconds Figure 1-a. Maximum time at Flash mode lash I T(MAX) 500us Figure 1-b. Flash mode ON time control Signal - 7 -

8 Current level when using lash I T(MAX) 500us lash I T(MAX) 500us I T(MAX) 500us Figure 1-c. Effect of Pin in Flash mode - 8 -

9 Count Time when using If. A < 2s A+B = 2s A (Torch mode) B (Flash mode) If. A > 2s A = 2s + a A (Torch mode) If. A < 2s A+B = 2s + a A (Flash mode) B (Torch mode) A = 2s A (Flash mode) A = (high) Flashlight(Torch) is used A (Torch mode) Figure 1-c. Effect of Pin in Flash mode - 9 -

10 Torch Mode - Current level in torch mode is set by NXA4001 serial interface. - The torch mode current level can be adjusted to 1 of 16 steps using a linear scale. - The maximum current of Torch mode is set one third of Flash mode current. - Torch mode operation is controlled entirely by the serial interface via the pin. - If the pin low state is longer than 500us, Torch Mode cannot be used. - In Torch mode, pin does not affect. - The Torch mode is changed to Flash mode after every 16th Rising clock. Torch Mode Command T1 T2 2nd Rising T1(High status) = Minimum 2us (Recommend:4us) T2(Low status) = Minimum 2us (Recommend:4us) I T(MAX) Figure 2-a. Maximum Current Torch mode T1 T2 16th Rising I T(MIN) Figure 2-b. Minimum Current Torch mode T1 T2 500us I T(MAX) Figure 2-c. Torch mode OFF Signal

11 Torch Mode Dimming Control - The NXA4001 torch mode current settings are controlled by using the pin. T1(High state) = Minimum 2us T1 T2(Low state) = Minimum 2us Maximum 500us If T2 > 500us, Chip Unable T2 Diming Data D0 D1 D2 D3 D D13 D14 D15 Figure 3. Dimming Data Diming Data Flash Mode & Torch Mode LED Current setting Flash to Torch Mode Current Ratio 0 Flash mode (Not Torch mode) 1 1/3 2 1/ / / / / /5 8 1/ / / /9 12 1/ / / /45 Table 1. Current Ratio - The maximum flash current is set by the R SET resistor. - For the desired flash current, the resistor value can be calculated using the following equation : lash = = = 1.5A - Torch mode current is divided by the dimming data

12 PCB Layout Guidelines The high frequency and large switching currents of the NXA4001 make the choice of layout important. The following steps should be used as a reference to ensure the device is stable and maintains proper voltage and current regulation across its intended operating voltage and current range. 1. Place C VCC on the top layer and as close to the device as possible. Connecting the input capacitor through short wide traces on both the VCC and GND terminals will reduce the inductive voltage spikes that occur during switching and which can corrupt the VCC line. 2. Place C VOUT on the top layer and as close as possible to the VOUT and GND terminal. The returns for both C VCC and CV OUT should come together at one point, and as close to the GND pin as possible. Connecting C VOUT through short wide traces will reduce the series inductance on the VOUT and GND terminals that can corrupt the VOUT and GND line and cause excessive noise in the device and surrounding circuitry. 3. Connect the inductor on the top layer close to the LX pin. There should be a low impedance connection from the inductor to SW due to the large DC inductor current, and at the same time the area occupied by the LX node should be small so as to reduce the capacitive coupling of the high dv/dt present at LX that can couple into nearby traces. 4. Consider additional PCB exposed area for the flash LED to maximize heat sinking capability. This may be necessary when using high current application and long flash duration application. 5. Connect the exposed pad to PGND or FGND. Connect AGND, FGND to GND as close as possible to the package. Figure 4. NXA4001 Application Board Schematic

13 Figure 5. NXA4001 Application Board Top Side Layout Figure 6. NXA4001 Application Board Bottom Side Layout Component Part Number Description Manufacturer Coil PCMB042T-1R0MS 1uH, 4.5A, 24mΩ Susumu Power LED W724C0 White Flash LED, 12W, 2.8A Seoul Semiconductor VOUT Capacitor C0805C225K8PACTU 2.2uF, 10V, X5R, 0805 WALSIN VCC Capacitor C0805C225K8PACTU 2.2uF, 10V, X5R, 0805 KEMET RSET Resistor R2012G153J1-8W150V 15KΩ, 5%, 1/4W, 0805 WALSIN Table 2. The Component used in the NXA4001 Application Board

14 Package Outline (WLCSP-9P) WLCSP 9P( 9-ball ) PACKAGE OUTLINE DIMENSIONS D d c1 c2 e E e1 e1 Top View Bottom View A2 B A1 A Side View Symbol Dimensions In Millimeters(mm) Dimensions In Inches A A A B c c D d E e e