NJW4616. Constant Current LED Driver with PWM Dimming Control V DD LED V REF (0.2V) R S EN/PWM GND

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1 Constant Current LED Driver with PWM Dimming Control NJW466 GENERAL DESCRIPTION The NJW466 is a constant current LED driver with PWM dimming control. The output current can be set by external sensing resister, and the NJW466 can set up to 3mA. Because the withstand voltage of the output (LED) pin is 4V, it can series-connect the LED depending on forward voltage of the LED. The LED dimming control can be regulated via PWM duty cycle. It is suitable for back light, light source and so on. PACKAGE OUTLINE NJW466U2 (SOT-89-5) FEATURES Supply Voltage Range 2.5V to 4V Output Voltage V LED =4V max. Output Current I LED =2mA to 3mA Output Current Accuracy.5% To of White LED can be operated. (at LED Vf=3.4V) Quiescent Current 45µA max. PWM Dimming Control and Enable Control (Common Pin) Over Current Protection Thermal Shutdown Protection LED Short Protection Package SOT-89-5 BLOCK DIAGRAM LED V REF (.2V) + R S Current Limit Thermal Shut Down LED Short Protection Control Logic Standby Timer GND EN/PWM Ver

2 PIN CONFIGURATION. EN/PWM GND 2. GND 3. R S 4. LED PIN DESCRIPTIONS Pin No. Pin Name I/O Function EN/PWM I Standby control pin and PWM signal input pin for dimming control. [At Standby] Normal operation: High Level. Standby mode: Low Level. [At PWM signal input] The LED dimming control can be regulated by PWM duty cycle. When this pin is open or input High level, I LED becomes set current by an external resistor (R S ). 2 GND - Ground pin 3 R S O Resistor connect pin of I LED setting. The LED current can be set with connected resistor (R S ) between R S pin and GND pin. R S [Ω] =.2 [V] / I LED [A] 4 LED O Constant current circuit output pin Connect cathode pin of LED. 5 - Power Supply pin Ver

3 ABSOLUTE MAXIMUM RATINGS (Ta = 25 C) PARAMETER SYMBOL RATINGS UNIT Supply Voltage -.3 to +45 V Output Voltage V LED -.3 to +45 V EN/PWM Pin Voltage V ENPWM -.3 to +45 V Power Dissipation P D 625 (*) 24 (*2) mw Junction Temperature Range T j -4 to +5 C Operating Temperature Range T opr -4 to +25 C Storage Temperature Range T stg -5 to +5 C (*) Mounted on glass epoxy board. ( mm: based on EIA/JEDEC standard size, 2Layers, Cu area mm 2 ) (*2) Mounted on glass epoxy board. ( mm: based on EIA/JEDEC standard, 4Layers), (For 4Layers: Applying mm inner Cu area and a thermal via hole to a board based on JEDEC standard JESD5-5) RECOMMENDED OPERATING CONDITIONS PARAMETER SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT Supply Voltage V Output Current I LED 2-3 ma Output Voltage V LED V ELECTRICAL CHARACTERISTICS (Unless otherwise noted, = 2V, V LED = V, R S = 2Ω, V ENPWM =, Ta = 25 C) PARAMETER SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT Quiescent Current I DD µa Quiescent Current at OFF State I DD_OFF V ENPWM = GND - -. µa Output Current Accuracy I LED % Output (LED) Pin Leak Current I LEAK V ENPWM = GND, = V LED = 4V - -. µa OFF Delay Time t D_OFF ms EN/PWM Pin ON Voltage V ENPWM_ON <5V, I LED = OFF ON.7 - V EN/PWM Pin ON Voltage2 V ENPWM_ON 2 5V, I LED = OFF ON V EN/PWM Pin OFF Voltage V ENPWM_OFF I LED = ON OFF -.5 V EN/PWM Pin Input Current I ENPWM µa R S Pin Output Current I OUT_RS LED = OPEN µa PWM Dimming ON Delay Time t PWM_ON R S =.62Ω, V ENPWM = L H - - µs PWM Dimming OFF Delay Time t PWM_OFF R S =.62Ω, V ENPWM = H L - - µs LED Short Protection Detect Voltage V LED_SHORT V Maximum Output Current I LED_MAX R S = Ω ma Ver

4 TYPICAL APPLICATION / V + (*3) LED I LED V REF (.2V) + R S I LED Output Current Wave Form at PWM Dimming Current Limit Thermal Shut Down LED Short Protection Control Logic R S : Current Sense Resistor H : ON L : OFF PWM : Dimming Control GND Standby Timer EN/PWM The R s Resistance Setting formula: R S ( ). 2( V ) I ( A) LED (*3) If the wiring from the power supply to the LED anode pin is long, the voltage may change due to the influence of the parasitic elements. As the countermeasure, it should connect a decoupling capacitor as close to the LED as possible Ver

5 TYPICAL CHARACTERISTICS 45 Quiescent Current vs. Supply Voltage [V LED =V, V ENPWM =, R S =2Ω] 45 Quiescent Current vs. Temperature [ =2V, V LED =V, V ENPWM =, R S =2Ω] 4 4 Quiescent Current : I DD [μa] Quiescent Current : I DD [μa] Supply Voltage : [V] Quiescent Current at OFF State : I DD_OFF [na] Quiescent Current at OFF State vs. Temperature [V LED =V, V ENPWM =GND, R S =2Ω] VDD=2.5V VDD=2V VDD=4V Output Pin Leak Current vs. Temperature [ =4V, V LED =4V, V ENPWM =GND, R S =2Ω] 45 OFF Delay Time vs. Temperature [ =2V, V LED =V] Output Pin Leak Current : I LEAK [na] VLED=V VLED=5V VLED=4V OFF Delay Time : t D_OFF [ms] Ver

6 TYPICAL CHARACTERISTICS EN/PWM Pin ON Voltage : V ENPWM_ON [V] EN/PWM Pin ON Voltage vs. Supply Voltage [V LED =V, R S =2Ω] Supply Voltage : [V] EN/PWM Pin ON Voltage : V ENPWM_ON [V] EN/PWM Pin ON Voltage vs. Temperature [ =2V, V LED =V, R S =2Ω] EN/PWM Pin OFF Voltage : V ENPWM_OFF [V] EN/PWM Pin OFF Voltage vs. Supply Voltage [V LED =V, R S =2Ω] Supply Voltage : [V] EN/PWM Pin OFF Voltage : V ENPWM_OFF [V] EN/PWM Pin OFF Voltage vs. Temperature [ =2V, V LED =V, R S =2Ω] EN/PWM Pin Input Current : I ENPWM [μa] EN/PWM Pin Input Current vs. EN/PWM Pin Voltage [ =V ENPWM, V LED =V, R S =2Ω] EN/PWM Pin Voltage : V ENPWM [V] Ver

7 TYPICAL CHARACTERISTICS PWM Dimming ON Delay Time: t PWM_ON [μs] PWM Dimming ON Delay Time vs. Output Current [ =2V, V LED =V] Output Current : I LED [ma] PWM Dimming OFF Delay Time : t PWM_OFF [μs] PWM Dimming OFF Delay Time vs. Output Current [ =2V, V LED =V] Output Current : I LED [ma] PWM Dimming ON Delay Time : t PWM_ON [μs] PWM Dimming ON Delay Time vs. Temperature [ =2V, V LED =V] RS=Ω RS=2Ω RS=.667Ω PWM Dimming OFF Delay Time : t PWM_OFF [μs] PWM Dimming OFF Delay Time vs. Temperature [ =2V, V LED =V].4 RS=Ω.2 RS=2Ω RS=.667Ω Output Current vs. Output Pin Voltage [ =2V, V ENPWM = ] Output Current vs. Temperature [ =2V, V LED =V, V ENPWM =, R S =2Ω] Output Current : I LED [ma] RS=Ω RS=2Ω RS=.667Ω Output Current : I LED [ma] Output Pin Voltage : V LED [V] Ver

8 TYPICAL CHARACTERISTICS LED Short Protection Voltage : V LED_SHORT/OFF [V] LED Short Protection Voltage vs. Temperature [ =2V, V ENPWM =, R S =Ω] Detect Voltage Release Voltage Maximum Output Current : I LED_MAX [ma] Maximum Output Current vs. Output Pin Voltage [ =2V, V ENPWM =, R S =Ω] 8 Release Voltage 7 Detect Voltage Output Pin Voltage : V LED [V] Maximum Output Current : I LED_MAX [ma] Maximum Output Current vs. Temperature [ =2V, V LED =V, V ENPWM =, R S =Ω] Temperature: [ºC] Output Current : I LED [ma] Output Current vs. Current Sense Resistance [ =2V, V ENPWM =, V LED =V]. Current Sense Resistance : R S [Ω] Ver

9 The number of LED series connection Application Manual It is necessary to drive LED that is the LED forward voltage (Vf) or more. When the LED was series connected, the supply voltage should be input sum of LED Vf (ΣLED Vf) the series connected or more. In NJW466, it is necessary as minimum V + that is ΣLED Vf + NJW466 output voltage (V LED = V). The maximum LED connected number that NJW466 can drive is limited by the recommended output voltage maximum value (4V). Moreover, it should be used with ΣLED Vf within 39V that is subtracted the V LED = V. The table below shows maximum LED number at each Vf. (All LED Vf assumes ideally same) LED Vf is up to 3.V up to 3 lights LED Vf is up to 3.2V up to 2 lights LED Vf is up to 3.5V up to lights LED Vf is up to 3.9V up to lights LED Vf is up to 4.3V up to 9 lights V + 4V (*4) (*3) Vf n pcs. = LEDVf 39V V REF (.2V) + LED R S Current Limit Thermal Shut Down LED Short Protection Control Logic Standby Timer GND EN/PWM (*4) If the wiring from the power supply to the pin is long, the voltage may change due to the influence of the parasitic elements. As the countermeasure, it should connect a decoupling capacitor as close to the pin as possible. Ver

10 PWM input pulse and PWM dimming accuracy The ILED transient behavior corresponding to PWM input pulse has some delay at rise/fall time. Application Manual PWM Input Pulse Output Current Pulse t PWM_ON t PWM_OFF Output Current PWM ON/OFF Propagation Delay ( Output Current Pulse Width Error : ε t = t PWM_ON - t PWM_OFF ) If enter a PWM signal with short pulse width, for the output current pulse width error becomes larger against the PWM input pulse width, it is incapable of accurate PWM dimming. The Output current pulse width error rate (ε t ) becomes the following value. ( ε t =t PWM_ON t PWM_OFF ) ε t = approx. 9µs (Output Current: I LED =3mA,Ta=25 C typ. <Reference Value> ) The actual value of the output current pulse width error rate can calculate by above error rate (ε t ) and the frequency and Duty of the PWM input pulse. (f PWM : PWM input pulse frequency, D: PWM input pulse Duty) Based on the allowable value of the output current pulse width error rate, you should determine the frequency and Duty of the PWM input pulse. PWM Input pulse width = D / ( / f PWM ) Output Current pulse width = PWM Input pulse width - ε t Output Current pulse width error rate = (Output Current pulse width - PWM Input pulse width) / PWM Input pulse width = -ε t / PWM Input pulse width [%] Output current pulse width error rate calculation example: operation with PWM input pulse frequency 2Hz and Duty% Output Current Duty [%]. PWM Input pulse width = [%] / ( / 2[Hz] ) = 5 [µs] Output Current pulse width error rate = -9 [µs] / 5 [µs] = -8 [%] Output Current Duty vs. PWM Input Pulse Duty ILED=2mA ILED=mA ILED=3mA Measurement Conditions Output Current (I LED) 2mA (R S = Ω) ma (R S = 2Ω) 3mA (R S =.667Ω) Supply Voltage 2V Output (LED) pin Input Voltage at V PWM Input Pulse 2Hz, to 5V Output Current I LED Pulse Width The time is more than 9% of set current. Ambient Temperature Ta=25ºC... PWM Input Pulse Duty [%] - - Ver

11 Application Manual Protection Circuit Over Current Protection (Refer to Maximum Output Current vs. Output Pin Voltage) This protection function limits the output current, when the RS pin and GND pin was shorted. The limited current is dependence on output (LED) pin voltage. When the output (LED) pin voltage is less than "LED Short Protection Detect Voltage", maximum output current is limited to approx. 55mA (output (LED) pin voltage=v, Ta=25 C). The output current returns to set current, when the short status is release. LED Short Protection (Refer to Maximum Output Current vs. Output Pin Voltage) This protection function limits the output current, when the output (LED) pin rises as in LED shorten at output FET ON. The output current is limited to approx. 3mA when the output (LED) pin voltage rose to approx. 2V. Thermal Shutdown Function (Refer to Output Current vs. Temperature) When junction temperature of the NJW466 exceeds the 6 C*, internal thermal shutdown circuit function stops the device function. When junction temperature decreases to 4 C* or less, the device operation returns to normal operation. The purpose of this function is to prevent malfunctioning of IC at the high junction temperature. Therefore it is not something that urges positive use. It should make sure to operate within the junction temperature range rated ( +5 C). *) Design value Ver

12 The Loss of Constant Current Driver Application Manual The power consumption of the LED lighting circuit is classified as "the power consumption of the constant current driver" "the power consumption of the LED" and "the power consumption of the current sense resistor (R S )". The loss of constant current driver is caused mainly by quiescent current (I DD ) and output current (I LED ). The power dissipation of the device can calculate by follow equation. V + (*4) (*3) P D I DD + (V LED - V RS ) I LED = I DD + (V + - LED Vf -.2) I LED [W] LEDVf I DD Rs pin voltage (V RS ):.2V ΣLED Vf represents the sum of the LED Vf of use. V REF (.2V) + LED R S I LED V LED - V RS e.g.) = V + = 2[V], I DD =33[µA], LED Vf = 9[V], I LED = 2[mA] Current Limit Thermal Shut Down LED Short Protection Standby Timer Control Logic P D 2[V] 33[µA] + (2[V] - 9[V] -.2[V]) 2[mA] 564[mW] GND EN/PWM As shown in the above equation, the loss of constant current driver will increase in proportion to the voltage difference between the LED driving voltage V + and ΣLED Vf. It should set the LED operating Voltage (V + ) and output current (I LED ) with consideration of P D. NJW466U2 (SOT-89-5) Power Dissipation (Topr=-4ºC to +25ºC, Tj=5ºC) 3 25 (*2) on 4 Layers Board The device power dissipation must be below the power dissipation rate of the device package including thermal derating to ensure correct operation. Package Power : Pd [mw] 2 5 (*) on 2 Layers Board Ambient Temperature : Ta [ºC] (*): Mounted on glass epoxy board. ( mm: based on EIA/JEDEC standard size, 2Layers, Cu area mm2) (*2): Mounted on glass epoxy board. ( mm: based on EIA/JEDEC standard, 4Layers), (For 4Layers: Applying mm inner Cu area and a thermal via hole to a board based on JEDEC standard JESD5-5) Ver

13 Application Manual Parallel Drive of NJW466 For applications that require more than 3mA, it can correspond by parallel connecting two or more NJW466. The LED current becomes sum of LED current of each NJW466. Each device accepts different set current. I LED [A] = I LED + I LED 2 =.2 / R S [Ω] +.2 / R S 2 [Ω] (e.g. I LED = 45 [ma] setting: R S =.667 [Ω], R S 2 =.33 [Ω] ) V + (*3) I LED (*4) I LED I LED 2 + LED + LED V REF (.2V) R S V REF (.2V) R S Current Limit Thermal Shut Down LED Short Protection Standby Timer Control Logic R S Current Limit R S 2 Thermal Shut Down LED Short Protection Standby Timer Control Logic GND EN/PWM GND EN/PWM PWM Ver

14 MEMO [CAUTION] The specifications on this databook are only given for information, without any guarantee as regards either mistakes or omissions. The application circuits in this databook are described only to show representative usages of the product and not intended for the guarantee or permission of any right including the industrial rights Ver