TB62731FUG

TB62731FUG MARKTECH | Alldatasheet

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Maximum output voltage: Vo ≤ 28 V Mean LED current values set according to external resistor 14 mA (typ.) @R_sens = 2.7 Ω 20 mA (typ.) @R_sens = 1.8 Ω Supply power: Up to 320 mW supported Compact package: SSOP6-P-0.95B, 6 pins Built-in temperature derating function: LED current derated automatically depending on temperature High power efficiency Up to 80% of peak power efficiency achieved using recommended components Ron = 2.0 Ω (typ.) @VIN = 3.2~5.5 V Built-in low Ron power MOS switch Pin assignment (top view) Weight: 0.016 g (typ.) K GND SHDN A GND VCC Company Headquarters

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Latham, New York 12110 Toll Free: 800.984.5337 Fax: 518.785.4725 Web: www.marktechopto.com | Email: info@marktechopto.com California Sales Office:

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Costa Mesa, California 92626 Toll Free: 800.984.5337 Fax: 714.850.9314 Company Headquarters Latham, New York 12110 Toll Free: 800.984.5337 Fax: 518.785.4725 Web: www.marktechopto.com | Email: info@marktechopto.com California Sales Office: Costa Mesa, California 92626 Toll Free: 800.984.5337 Fax: 714.850.9314

K Pin connecting LED cathode to resistor used to set current. Feedback pin for voltage waveforms for controlling the LED constant current. 2, 5 GND Ground pin for the logic SHDN IC enable pin. Low, Standby Mode takes effect and pin A is turned off. VCC Input pin for power supply for operating the IC. Operating voltage range: 3.0~5.5 V A DC-DC converter switch pin. The switch is an N-channel MOSFET transistor. Note: Connect both GND pins to ground. SHDN OSC S Q R Buffer 350 kHz STB 0.12 V A VCC REF i (add) i (sub) A K GND GND 0.5 Ω

Absolute Maximum Ratings (unless otherwise specified, Topr = 25°C) Characteristics Symbol Rating Unit Supply voltage VCC −0.3~+6.0 V Input voltage VIN −0.3~+VCC + 0.3 V Pin A (anode) current Io (A) +270 mA Pin A voltage Vo (A) −0.3~+28 V 0.41 (IC only) Power dissipation PD 0.47 (IC mounted on PCB) (Note) W Rth (j-a) 1 300 (IC only) Saturation thermal resistance Rth (j-a) 2 260 (IC mounted on PCB) °C/W Operating temperature range Topr −40~+85 Storage temperature range Tstg −40~+150 Maximum junction temperature Tj 125 Note: The power dissipation is derated by 3.8 mW/°C from the maximum rating for every 1°C exceeding the ambient temperature of 25°C (when the IC is mounted on a PCB). Recommended Operating Conditions (unless otherwise specified, Topr = −40~85°C) Characteristics Symbol Test circuit Test condition Min Typ. Max Unit Supply voltage VCC 3.0 4.3 V SHDN pin high-level input voltage VIH VCC − 0.5 VCC V SHDN pin low-level input voltage VIL 0.5 V SHDN pin high-level input pulse width tpw SHDN 500 µs Set LED current (mean) Io Vo (A) = VIN 3.0 V, VOUT 16 V mA

Electrical Characteristics (unless otherwise specified, Ta = −40~85°C, VCC = 3.0~5.5 V) Characteristics Symbol Test circuit Test condition Min Typ. Max Unit Supply voltage VCC 3.0 5.5 V Current consumption at operation ICC (ON) VCC = 3.6 V 0.6 0.9 mA Current consumption at standby ICC (SHDN) SHDN = 0 V 0.5 1.0 µA SHDN pin current I_SHDN SHDN = VCC, Built-in pull-down resistor 4.2 µA Internal MOS transistor on-resistance Ron I (A) <= 270 mA, Including detected resistance 2.0 2.5 Ω Internal MOS transistor switching frequency fOSC 275 350 425 kHz Pin A voltage Vo (A) V Pin A current Io (A) 210 240 270 mA Pin A leakage current Ioz (A) 0.5 µA Set LED current (mean) Io VCC = 3.2~4.2 V, R_sens = 1.8 Ω Topr = 25°C (Note 1) 17.6 22.4 mA Pin K derating start ambient temperature Tdel Equivalent to R_sens = 1.8 Ω, L = 4.7 µH, VO = 16 V (Note 2) Note 1: Due to operation of the temperature derating function, measure when Ta = 25°C. Note that fluctuation in R_sens resistors is not included in the specified value. Io may be different from the specified value due to the relation between the inductor value and load. Note 2: This rating is guaranteed by the design.

Figure 3 Burst Control Waveforms Burst Control Burst control is control of the number of current pulses, shown in the graph on the previous page. Control is repeated in desired cycles. The current pulse in the graph is the charged current on capacitor 2 (C2) for output. The current pulse is supplied to the LED as current discharged from the output-side capacitor. The current pulse flows to GND via R_sens. The waveform of the voltage charged on the output-side capacitor is fed back to the IC from pin K via C2. The internal circuit which uses pin K for input controls the number of current pulses so that the mean voltage value of the obtained voltage waveform is 36 mV. As a result, the output current is controlled as the constant current (= mean current). Connecting R_sens = 1.8 Ω obtains the mean current (36 mV ÷ 1.8 Ω = 20 mA). Current is controlled by PFM (pulse frequency modulation) because the time when the output pulse is generated varies (increases/decreases). A prerequisite is that the input power from VIN is larger than the output power to the LED load. The constant current is maintained by fixing a pulse stop time of 7.5~15 µs and increasing/decreasing the number of current pulses. The number of current pulses is fewer when the input power exceeds the output power, larger when the input power is less than the output power. The burst frequency (pulse generation frequency) at controlled constant current is calculated as follows: fburst [Hz] = (number of current pulses x (1/275~1/350 kHz) + pulse stop time (7.5~15 µs) . . . formula 1 The IC is designed to supply a load power of 320 mW (min). Generally, a step-up inductance of 47 µH is used for optimum design for the load power of 320 mW. When the load power is small, the inductance must be small. Make sure the following condition for LED load between pins A and K is satisfied: VIN (VCC) < LED Vf total Note that, regardless of control by the IC, LEDs are always on. Pin A voltage Pin A current (external inductance current) Pin K voltage (current charged on capacitor) Pulse output time width fOSC = 350 kHz Maximum duty width for inductor on: 83.3% of fOSC Pulse stop time width: 7.5 µs (min)~15 µs (max) Repetition of waveforms at left I A (peak) = 240 mA (typ.)

The SHDN pin is used to set normal or standby operation. When SHDN is set to Low, the operation is standby; when the pin is High, the LED is turned on. Current consumption in Standby Mode is 1 µA (max). Output-side capacitor setting When the output-side capacitor (C2) = 0.1 µF, the peak current to be supplied to LEDs is expected to be the set current +5~+8 mA. When C2 = 0.01 µF, the peak current is expected to be the set current +20~30 mA; when C2 = 1 µF, it is the set current +2~3 mA. Toshiba recommend C2 = 1 µF or more considering the LED max If. The IC is used only for lighting LEDs. The IC does not finely control output current ripples. This is because eliminating ripples is considered unnecessary as the LED emittance is recognized as the integral amount. External inductance setting The minimum external inductance is calculated as follows: L (µH) = ((K × Po) − VIN min × Io) × (1/fOSC min) × 2 × (1/Ip min × Ip min) . . . formula 2 The above parameters are described below: Po: output power (power required by LED load) Po (W) = Vf LED × If LED + Vf schottky × If LED + R_sens × If LED × If LED LED forward current: If LED (mA) = Set current: Io (mA), LED forward voltage: Vf LED (V), schottky diode forward voltage: Vf schottky (V), Setting resistance: R_sens (Ω) VIN min (V): minimum input voltage (battery voltage) If the input voltage includes a resistance component, take the voltage drop into consideration for the minimum input voltage. The input current IIN is roughly estimated as follows: IIN (mA) = VfLED × Io × (1/η) × (1/VIN) . . . formula 3 When min VIN = 3.2 (V), VfLED = 16 (V), Io = 18 (mA), and η >= 75 (%), then IIN = 0.12 (mA). As a result, the voltage drops by 1.2 V due to the 1-Ω DC resistance component. Because the IC’s minimum VCC = 3.0 V, the minimum VIN is 3.12 V (VIN >= 3.12 V). Io (A): Mean current value set according to resistance R_sens (Ω) fOSC (Hz): Switching frequency of internal MOS transistor Specified values for fOSC (kHz): 275 min, 350 typ., 475 max Ip (A): Peak current value supplied to external inductor Specified values for Ip (A): 230 min, 240 typ., 270 max K: Margin of output power K = 1.1~1.3 The ideal condition is to give 1.05 to 1.3 times the output power Po as the input power. The loss of the IC is assumed to be included in the margin. If K is too large, it may not be possible for the current characteristic to be the specified value. Note that K > 1.

Substitute the following conditions in formula 2. Supply voltage VIN = 3.0~4.3 (V) Output-side capacitor C2 = 1 (µF) . . . C2 is ignored in the calculation. Where it is assumed that, VfLED = 16 (V), Vf schottky = 0.3 (V), R_sens = 1.8 (Ω), Io = 20 (mA), K = 1.1 VfLED: LED Vf Vf schottky: schottky diode Vf R_sens: setting resistance Io: set current K: margin 43.8 (µH, VIN = 4.3 V) Thus, 48.1 (µH) is selected when the input voltage is low, 3.0 V. Note that the calculation does not consider fluctuations in inductance. Toshiba recommend selection of an inductance of 1.2 times the calculated value. The recommended inductance under the above conditions is L (µH) = 48.1 (µH) × 1.2 > = 57.7 (µH).

Selection of R_sens Resistance between pin K and GND R_sens (Ω) is used for setting output current Io. The mean output current Io can be set according to the resistance. The mean current Io (mA) to be set is roughly calculated as follows: Io (mA) = 36 (mV) ÷ R_sens (Ω) For example, when R_sens = 1.8 (Ω), Io = 20 (mA). Take a current error of ±10% (not including R_sens error) into consideration. The IC has a minimum output Po = 320 (mA, choke coil = 47 µH). At that time, if the product of mean current Io and output voltage Vo exceeds Po = 320 (mW), mean current Io may become less than the desired value. If the IC is not connected to the output-side capacitor (for smoothing), the set current Io can be obtained. At that time, because the current flowing to the LED is a pulse current with a maximum peak value of 270 mA, make sure that surge current IFP (mA) does not flow to the LED. Toshiba recommend use of components with low reactance (parasitic inductance) and minimized PCB wiring. Toshiba also recommend allocating components in the application circuit diagram as near each other as possible. Figure 4 Resistance for setting current R_sens (Ω) Relation between set current IO and setting resistance R_sens (typical value: VCC = 3.6 V, Ta = 25°C) Set current IO (mA) 1.2 : Io (mA)

Toshiba recommend derating the LED current depending on the increase in ambient temperature. The TB62731FUG is designed to ensure safe and efficient driving of white LEDs used as backlight sources for color LCDs. The IC incorporates a function that derates current according to the set temperature (the ambient temperature when the IC is mounted), Ta. The IC features an output current that varies according to the internally-detected temperature Tjs as follows: when Tjs = 45 (°C), output current is 100%; when Tjs = 100 (°C), output current is 0%. The derating start temperature Ts (°C) is determined based on Ta (Ta = Ts when the IC is not operating) by subtracting the self-generated temperature Tup (°C) from Tjs = 45 (°C). Ts (°C) = 45 (°C) − Tup (°C) . . . formula 4 The derating characteristic is as shown in the graph below, Figure 5, which shows the relation between output current change ratio and internally-detected temperature (IC temperature) Tjs. The self-generated temperature Tup (°C) is calculated as follows: Tup (°C) = (P loss (W) − P parts (W)) × θja (°C/W) ) . . . formula 5 P loss: power loss P parts: power loss of parts θja: package saturation thermal resistance (Ω) The parameters are described below: DC resistance of inductor: RDC (Ω) LED forward current: If LED (A) LED forward voltage: Vf LED (V) Schottky diode forward voltage: Vf schottky (V) Setting resistance: R_sens P loss (W) ∼ −Po (W) ÷ η (%) − Po (W) Po: output power η: power efficiency P parts (W) ∼ −RDC × IIN + Vf schottky × If LED + R_sens × If LED × If LED θja (°C/W) ≤ 260 (°C/W) max when IC mounted on PCB Po (W) = Vo (V) × Io (A) Vo: Vf LED output voltage Io: mean output current = set current Pi (W) = VIN (V) × IIN (A) Pi: input power VIN: input voltage IIN: mean input current Example of calculation: Where the measurement result for any lighting circuit shows the following values: RDC = 0.5 (Ω), Po = 320 (mW), IIN = 0.1 (mA), Io = 20 (mA), R_sens = 1.8 (Ω), Vf schottky = 0.3 (V), and η = 70 (%)

The self-generated temperature Tup (°C) is calculated as follows: Thus, the derating start temperature Ts (°C) is calculated as follows: As a result, Io is controlled in the recommended current range as shown in Figure 5. Since saturation thermal resistance θja = 260 (°C/W) is the maximum value, θja = 210~260 (°C/W) is used as a mounting condition. Depending on the IC characteristics, peripherals, and use environment, the derating start temperature fluctuates among ICs. Figure 5 Derating Function of Set Current 100 100 120 Change from Ts = 34.8°C (20 mA = 100%) Change according to Tjs Recommended LED current range (converted by 25 mA) Temperatures Ts (°C) and Tjs (°C) Output current change ratio (%) [%]

Current consumption at normal operation ICC (ON) Current consumption at shutdown ICC (SHDN) Output switching frequency VCC (V) VCC (V) VCC (V) Current consumption (µA) Current consumption at shutdown (µA) Output switching frequency (kHz) 0.5 0.3 0.1 5.5 4.5 0.2 0.4 3.5 300 400 360 320 5.5 4.5 340 380 3.5 TB62731FUG VCC TB62731FUG VCC TB62731FUG VCC fOSC 900 300 800 100 5.5 500 4.5 200 600 400 700 3.5

Application Circuit Example 1 (characteristic using recommended coil as reference) Though it is necessary to consider the DC resistance of L1, an inductance of 33 to 47 (typ.) to 68 µH is suitable for turning on four LEDs. Input voltage VIN (V) Input voltage – power efficiency/mean current Input voltage VIN (V) Power efficiency η (%) Mean current IF (mA) 100 4.2 3.2 3.6 3.8 3.4 η IF 100 4.2 3.2 3.6 3.8 3.4 η IF 100 4.2 3.2 3.6 3.8 3.4 η IF Input voltage – power efficiency/mean current Input voltage VIN (V) Power efficiency η (%) Mean current IF (mA) Input voltage – power efficiency/mean current Power efficiency η (%) Mean current IF (mA) L1: Toko A914BYW-470M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 R_ sens 1.8 Ω VIN 3.2 V~4.2 V 10 µF ON OFF IF 20 mA 47 µH S-Di 1 µF VCC A SHDN GND GND K L1: Toko A914BYW-470M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 R_ sens 1.8 Ω VIN 3.2 V~4.2 V 10 µF ON OFF 47 µH S-Di 1 µF VCC A SHDN GND GND K IF 20 mA L1: Toko A914BYW-470M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 R_sens 1.8 Ω VIN 3.2 V~4.2 V 10 µF ON OFF IF 20 mA 47 µH S-Di 1 µF VCC A SHDN GND GND K

Application Circuit Example 2 (characteristic using flat coil for handy terminal as reference) Flat coils suitable for handy terminals have a large DC resistance; thus, the power efficiency drops slightly, to about 70%. Input voltage VIN (V) Input voltage – power efficiency/mean current Power efficiency η (%) Average IF (mA) Input voltage – power efficiency/mean current Input voltage VIN (V) Power efficiency η (%) Average IF (mA) Input voltage – power efficiency/mean current Input voltage VIN (V) Power efficiency η (%) Average IF (mA) 100 4.2 3.2 3.6 3.8 3.4 η IF 100 4.2 3.2 3.6 3.8 3.4 η IF 100 4.2 3.2 3.6 3.8 3.4 η IF L1: Toko A914BYW-270M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Susumu RL0510S-1R8 R_sens 1.8 Ω VIN 3.2 V~4.2 V 10 µF ON OFF IF 20 mA 27 µH S-Di 1 µF VCC A SHDN GND GND K L1: TDK LDR344812T-390 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Susumu RL0510S-1R8 R_sens 1.8 Ω VIN 3.2 V~4.2 V 10 µF ON OFF IF 20 mA 39 µH S-Di 1 µF VCC A SHDN GND GND K L1: TDK LDR344812T-440 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 R_sens 1.8 Ω VIN 3.2 V~4.2 V 10 µF ON OFF IF 20 mA or 16 mA 44 µH S-Di 1 µF VCC A SHDN GND GND K

Power efficiency η (%) Input voltage VIN (V) 100 4.2 3.2 3.6 3.8 3.4 η IF 100 4.2 3.2 3.6 3.8 3.4 η IF Input voltage – power efficiency/mean current Power efficiency η (%) Mean current IF (mA) Input voltage – power efficiency/mean current Input voltage VIN (V) Mean current IF (mA) L1: Toko A914BYW-4R7 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: ⎯ R_sens 5.1 Ω VIN 3.2 V~4.2 V 4.7 µF ON OFF IF 8.5 mA 4.7 µH S-Di 1 µF VCC A SHDN GND GND K L1: Sumitomo Special Metals CXLD (CXAD) 120-150 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: ⎯ R_sens 2.4 Ω VIN 3.2 V~4.2 V 4.7 µF ON OFF IF 8.5 mA 15 µH S-Di 1 µF VCC A SHDN GND GND K

Weight: 0.016 g (typ.)

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• TOSHIBA products should not be embedded to the downstream products which are prohibited to be produced and sold, under any law and regulations. 030619EBA RESTRICTIONS ON PRODUCT USE About solderability, following conditions were confirmed
• Solderability (1) Use of Sn-63Pb solder Bath
• solder bath temperature = 230°C
• dipping time = 5 seconds
• the number of times = once
• use of R-type flux (2) Use of Sn-3.0Ag-0.5Cu solder Bath
• solder bath temperature = 245°C
• dipping time = 5 seconds
• the number of times = once
• use of R-type flux