TB62731FUG TOSHIBA BiCD Digital Integrated Circuit Silicon Monolithic TB62731FUG Step-up DC-DC Converter for White LED Driver The TB62731FUG is an LED driver that uses a high power efficiency step-up DC-DC converter. The converter turns on/off 2 to 6 white LEDs in series. The IC incorporates an N-channel MOSFET transistor used for coil-switching and a function that reduces the LED current in response to increase in temperature. The mean LED current can be easily set using an external resistor. The IC is ideal as a driver for LED light sources used as liquid crystal backlights for PDAs, cellular phones, and handy terminals. The suffix (G) appended to the part number represents a Lead (Pb) -Free product. Weight: 0.016 g (typ.) Features • 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) K A GND GND SHDN VCC 1 2006-06-14 TB62731FUG Block Diagram A VCC S OSC R Q Buffer 350 kHz REF 0.5 Ω STB 0.12 V SHDN K A i (add) i (sub) GND GND Pin Functions No Symbol Function 1 K 2, 5 GND Ground pin for the logic 3 SHDN IC enable pin. Low, Standby Mode takes effect and pin A is turned off. 4 VCC Input pin for power supply for operating the IC. Operating voltage range: 3.0~5.5 V 6 A DC-DC converter switch pin. The switch is an N-channel MOSFET transistor. Pin connecting LED cathode to resistor used to set current. Feedback pin for voltage waveforms for controlling the LED constant current. Note: Connect both GND pins to ground. 2 2006-06-14 TB62731FUG 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) Rth (j-a) 2 260 (IC mounted on PCB) Operating temperature range Topr −40~+85 °C Storage temperature range Tstg −40~+150 °C Tj 125 °C Saturation thermal resistance Maximum junction temperature °C/W Note: The power dissipation is derated by 3.8 mW/°C from the Absolute 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 Supply voltage Symbol Test circuit Test condition VCC ⎯ Min Typ. Max Unit ⎯ 3.0 ⎯ 4.3 V ⎯ VCC V SHDN pin high-level input voltage VIH ⎯ ⎯ VCC − 0.5 SHDN pin low-level input voltage VIL ⎯ ⎯ 0 ⎯ 0.5 V tpw SHDN ⎯ ⎯ 500 ⎯ ⎯ µs Io ⎯ Vo (A) = VIN 3.0 V, VOUT 16 V 5 ⎯ 20 mA SHDN pin high-level input pulse width Set LED current (mean) 3 2006-06-14 TB62731FUG Electrical Characteristics (unless otherwise specified, Ta = −40~85°C, VCC = 3.0~5.5 V) Symbol Test circuit Test condition Min Typ. Max Unit VCC ⎯ ⎯ 3.0 ⎯ 5.5 V ICC (ON) ⎯ VCC = 3.6 V ⎯ 0.6 0.9 mA ICC (SHDN) ⎯ SHDN = 0 V ⎯ 0.5 1.0 µA I_SHDN ⎯ SHDN = VCC, Built-in pull-down resistor ⎯ 4.2 7 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) ⎯ ⎯ 28 ⎯ ⎯ V Pin A current Io (A) ⎯ ⎯ 210 240 270 mA Pin A leakage current Ioz (A) ⎯ ⎯ ⎯ 0.5 1 µA Io ⎯ VCC = 3.2~4.2 V, R_sens = 1.8 Ω Topr = 25°C 17.6 20 22.4 mA ⎯ 45 (Note 2) ⎯ °C Characteristics Supply voltage Current consumption at operation Current consumption at standby SHDN pin current Set LED current (mean) Pin K derating start ambient temperature Tdel ⎯ (Note 1) Equivalent to R_sens = 1.8 Ω, L = 4.7 µH, VO = 16 V 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. 4 2006-06-14 TB62731FUG IL, ILpeak A VCC S OSC R Q Buffer NMOS 350 kHz C2 SHDN C1 Io 0.5 Ω STB 0.12 V VIN Ic2 K A REF i (add) i (sub) R_sens GND Figure 1 Application Circuit The basic TB62731FUG circuit uses a step-up DC-DC converter and burst control of the current pulse. Basic Operation The internal MOS transistor (NMOS) is turned on at f OSC = 350 kHz, charging energy to the inductor. The inductance current IL increases from 0. When IL = ILpeak = 240 mA (typ.) or when 5/6 (83.3%) of fOSC (= 350 kHz) is reached, the transistor is turned off. At that time, the coil maintains IL = ILpeak, the Schottky diode is turned on, and IL = Ic2 flows. Then, Ic2 decreases, reaching IL = 0. The above operation repeats. When Ic2 is fully charged, the surplus current becomes Io, which flows to the LED. The graph below shows details of the basic pulse used for burst control. ILpeak = 240 mA (typ.) IL, ILpeak Maximum duty: 83.3% of fOSC With low inductance With high inductance T = 1/fOSC, fOSC = 350 kHz (typ.) Figure 2 Switching Waveform of Inductance 5 2006-06-14 TB62731FUG Maximum duty width for inductor on: 83.3% of fOSC Pulse stop time width: 7.5 µs (min)~15 µs (max) Pulse output time width fOSC = 350 kHz Repetition of waveforms at left Pin A voltage Pin A current (external inductance current) I A (peak) = 240 mA (typ.) Pin K voltage (current charged on capacitor) 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. 6 2006-06-14 TB62731FUG Standby Operation 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. 7 2006-06-14 TB62731FUG 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 L (µH) = ((1.1 × 16 × 0.02) − 3 × 0.02) × (1/275e3) × 2 × (1/(0.21 × 0.21)) = 48.1 (µH, VIN = 3.0 V) 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). 8 2006-06-14 TB62731FUG 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. Relation between set current IO and setting resistance R_sens (typical value: VCC = 3.6 V, Ta = 25°C) 40 : Io (mA) Set current IO (mA) 30 20 10 0 10 9.1 8.2 6.8 5.6 4.7 3.3 2.7 2.2 2 1.8 1.5 1.2 1 Resistance for setting current R_sens (Ω) Figure 4 9 2006-06-14 TB62731FUG Output Derating Function 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 η (%) = 100 × Po (W) ÷ Pi (W) 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 (%) 10 2006-06-14 TB62731FUG The self-generated temperature Tup (°C) is calculated as follows: Tup (°C) = ((0.32 − (0.32 × 0.7)) − (0.5 × 0.1 + 0.3 × 0.02 + 1.8 × 0.02 × 0.02)) × 260 = 10.2 (°C) Thus, the derating start temperature Ts (°C) is calculated as follows: Ts (°C) = 45 (°C) − 10.4 (°C) = 34.8 (°C) As a result, Io is controlled in the recommended current range as shown in Figure 5. Output current change ratio (%) [%] 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. 120 100 80 60 40 20 0 0 Change from Ts = 34.8°C (20 mA = 100%) Change according to Tjs Recommended LED current range (converted by 25 mA) 25 50 75 100 Temperatures Ts (°C) and Tjs (°C) Figure 5 Derating Function of Set Current 11 2006-06-14 TB62731FUG Current consumption at normal operation ICC (ON) 900 Current consumption (µA) 800 VCC 700 600 4 3 500 1 TB62731FUG 6 400 2 300 5 200 100 0 3 3.5 4 4.5 5 5.5 VCC (V) Current consumption at shutdown ICC (SHDN) Current consumption at shutdown (µA) 0.5 0.4 VCC 4 0.3 3 1 TB62731FUG 6 0.2 2 5 4 3 0.1 0 3 3.5 4 4.5 5 5.5 VCC (V) Output switching frequency Output switching frequency (kHz) 400 380 VCC 360 1 TB62731FUG 6 340 2 fOSC 5 320 300 3 3.5 4 4.5 5 5.5 VCC (V) 12 2006-06-14 TB62731FUG 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. L1 47 µH VIN 3.2 V~4.2 V Input voltage – power efficiency/mean current S-Di 100 25 (%) GND K GND R_sens 1.8 Ω 80 20 IF IF 20 mA 70 60 15 Mean current SHDN OFF η C1 10 µF Power efficiency ON C2 1 µF (mA) 90 A VCC 50 η L1: Toko A914BYW-470M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 L1 47 µH VIN 3.2 V~4.2 V IF 40 3.2 3.4 3.6 3.8 Input voltage VIN 10 4.2 4 (V) Input voltage – power efficiency/mean current S-Di 100 25 (%) GND K GND R_ sens 1.8 Ω 80 20 IF IF 20 mA 70 60 15 Mean current SHDN OFF η C1 10 µF C2 1 µF Power efficiency ON A (mA) 90 VCC 50 η IF L1: Toko A914BYW-470M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 L1 47 µH VIN 3.2 V~4.2 V 40 3.2 3.4 3.6 3.8 Input voltage VIN 10 4.2 4 (V) Input voltage – power efficiency/mean current S-Di 100 25 (%) GND K GND R_ sens 1.8 Ω 80 20 IF IF 20 mA 70 60 15 Mean current SHDN OFF η C1 10 µF C2 1 µF Power efficiency ON A (mA) 90 VCC 50 η L1: Toko A914BYW-470M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 IF 40 3.2 3.4 3.6 3.8 Input voltage VIN 13 4 10 4.2 (V) 2006-06-14 TB62731FUG 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%. L1 44 µH VIN 3.2 V~4.2 V Input voltage – power efficiency/mean current S-Di 100 25 GND K GND R_sens 1.8 Ω 20 (mA) 80 IF IF 20 mA or 16 mA 70 60 15 Average SHDN OFF η C2 1 µF Power efficiency ON C1 10 µF A (%) 90 VCC 50 η IF L1: TDK LDR344812T-440 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Rohm MCR03-1R8 L1 39 µH VIN 3.2 V~4.2 V 40 3.2 3.4 3.6 3.8 Input voltage VIN 10 4.2 4 (V) Input voltage – power efficiency/mean current S-Di 100 25 (%) GND K GND R_sens 1.8 Ω 80 20 IF IF 20 mA 70 60 15 Average SHDN OFF η C1 10 µF C2 1 µF Power efficiency ON A (mA) 90 VCC 50 η IF L1: TDK LDR344812T-390 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Susumu RL0510S-1R8 L1 27 µH VIN 3.2 V~4.2 V 40 3.2 3.4 3.6 3.8 Input voltage VIN 10 4.2 4 (V) Input voltage – power efficiency/mean current S-Di 100 25 (%) GND K GND R_sens 1.8 Ω 20 IF OFF 80 70 60 15 Average IF 20 mA η SHDN C2 1 µF Power efficiency ON C1 10 µF A (mA) 90 VCC 50 η IF L1: Toko A914BYW-270M S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: Susumu RL0510S-1R8 40 3.2 3.4 3.6 3.8 Input voltage VIN 14 4 10 4.2 (V) 2006-06-14 TB62731FUG IF 8.5 mA OFF GND 90 9 80 8 K GND 70 7 R_sens 5.1 Ω 60 6 50 L1 15 µH 5 η IF L1: Toko A914BYW-4R7 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: ⎯ VIN 3.2 V~4.2 V (mA) 10 IF SHDN 100 (%) C2 1 µF η C1 4.7 µF A Power efficiency ON VCC Input voltage – power efficiency/mean current S-Di Mean current L1 4.7 µH VIN 3.2 V~4.2 V 40 3.2 3.4 3.6 3.8 Input voltage VIN 4 4.2 4 (V) Input voltage – power efficiency/mean current S-Di 100 20 GND K GND R_sens 2.4 Ω 15 (mA) (%) 10 80 IF IF 8.5 mA OFF η C1 4.7 µF SHDN C2 1 µF Power efficiency ON A Mean current 90 VCC 70 60 5 50 η L1: Sumitomo Special Metals CXLD (CXAD) 120-150 S-Di: Toshiba 1SS404 20 V/1A LED: Nichia NSCW215T R_sens: ⎯ IF 40 3.2 3.4 3.6 3.8 Input voltage VIN 15 4 0 4.2 (V) 2006-06-14 TB62731FUG Package Dimensions Weight: 0.016 g (typ.) 16 2006-06-14 TB62731FUG Notes on Contents 1. Block Diagrams Some of the functional blocks, circuits, or constants in the block diagram may be omitted or simplified for explanatory purposes. 2. Equivalent Circuits The equivalent circuit diagrams may be simplified or some parts of them may be omitted for explanatory purposes. 3. Timing Charts Timing charts may be simplified for explanatory purposes. 4. Application Circuits The application circuits shown in this document are provided for reference purposes only. Thorough evaluation is required, especially at the mass production design stage. Toshiba does not grant any license to any industrial property rights by providing these examples of application circuits. 5. Test Circuits Components in the test circuits are used only to obtain and confirm the device characteristics. These components and circuits are not guaranteed to prevent malfunction or failure from occurring in the application equipment. IC Usage Considerations Notes on Handling of ICs (1) The absolute maximum ratings of a semiconductor device are a set of ratings that must not be exceeded, even for a moment. Do not exceed any of these ratings. Exceeding the rating(s) may cause the device breakdown, damage or deterioration, and may result injury by explosion or combustion. (2) Use an appropriate power supply fuse to ensure that a large current does not continuously flow in case of over current and/or IC failure. The IC will fully break down when used under conditions that exceed its absolute maximum ratings, when the wiring is routed improperly or when an abnormal pulse noise occurs from the wiring or load, causing a large current to continuously flow and the breakdown can lead smoke or ignition. To minimize the effects of the flow of a large current in case of breakdown, appropriate settings, such as fuse capacity, fusing time and insertion circuit location, are required. (3) If your design includes an inductive load such as a motor coil, incorporate a protection circuit into the design to prevent device malfunction or breakdown caused by the current resulting from the inrush current at power ON or the negative current resulting from the back electromotive force at power OFF. IC breakdown may cause injury, smoke or ignition. Use a stable power supply with ICs with built-in protection functions. If the power supply is unstable, the protection function may not operate, causing IC breakdown. IC breakdown may cause injury, smoke or ignition. (4) Do not insert devices in the wrong orientation or incorrectly. Make sure that the positive and negative terminals of power supplies are connected properly. Otherwise, the current or power consumption may exceed the absolute maximum rating, and exceeding the rating(s) may cause the device breakdown, damage or deterioration, and may result injury by explosion or combustion. In addition, do not use any device that is applied the current with inserting in the wrong orientation or incorrectly even just one time. 17 2006-06-14 TB62731FUG (5) Carefully select external components (such as inputs and negative feedback capacitors) and load components (such as speakers), for example, power amp and regulator. If there is a large amount of leakage current such as input or negative feedback condenser, the IC output DC voltage will increase. If this output voltage is connected to a speaker with low input withstand voltage, overcurrent or IC failure can cause smoke or ignition. (The over current can cause smoke or ignition from the IC itself.) In particular, please pay attention when using a Bridge Tied Load (BTL) connection type IC that inputs output DC voltage to a speaker directly. 18 2006-06-14 TB62731FUG Points to Remember on Handling of ICs (1) Heat Radiation Design In using an IC with large current flow such as power amp, regulator or driver, please design the device so that heat is appropriately radiated, not to exceed the specified junction temperature (Tj) at any time and condition. These ICs generate heat even during normal use. An inadequate IC heat radiation design can lead to decrease in IC life, deterioration of IC characteristics or IC breakdown. In addition, please design the device taking into considerate the effect of IC heat radiation with peripheral components. (2) Back-EMF When a motor rotates in the reverse direction, stops or slows down abruptly, a current flow back to the motor’s power supply due to the effect of back-EMF. If the current sink capability of the power supply is small, the device’s motor power supply and output pins might be exposed to conditions beyond absolute maximum ratings. To avoid this problem, take the effect of back-EMF into consideration in system design. 19 2006-06-14 TB62731FUG About solderability, following conditions were confirmed • Solderability (1) Use of Sn-37Pb 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 RESTRICTIONS ON PRODUCT USE 060116EBA • The information contained herein is subject to change without notice. 021023_D • TOSHIBA is continually working to improve the quality and reliability of its products. Nevertheless, semiconductor devices in general can malfunction or fail due to their inherent electrical sensitivity and vulnerability to physical stress. It is the responsibility of the buyer, when utilizing TOSHIBA products, to comply with the standards of safety in making a safe design for the entire system, and to avoid situations in which a malfunction or failure of such TOSHIBA products could cause loss of human life, bodily injury or damage to property. In developing your designs, please ensure that TOSHIBA products are used within specified operating ranges as set forth in the most recent TOSHIBA products specifications. Also, please keep in mind the precautions and conditions set forth in the “Handling Guide for Semiconductor Devices,” or “TOSHIBA Semiconductor Reliability Handbook” etc. 021023_A • The TOSHIBA products listed in this document are intended for usage in general electronics applications (computer, personal equipment, office equipment, measuring equipment, industrial robotics, domestic appliances, etc.). These TOSHIBA products are neither intended nor warranted for usage in equipment that requires extraordinarily high quality and/or reliability or a malfunction or failure of which may cause loss of human life or bodily injury (“Unintended Usage”). Unintended Usage include atomic energy control instruments, airplane or spaceship instruments, transportation instruments, traffic signal instruments, combustion control instruments, medical instruments, all types of safety devices, etc. Unintended Usage of TOSHIBA products listed in this document shall be made at the customer’s own risk. 021023_B • The products described in this document shall not be used or embedded to any downstream products of which manufacture, use and/or sale are prohibited under any applicable laws and regulations. 060106_Q • The information contained herein is presented only as a guide for the applications of our products. No responsibility is assumed by TOSHIBA for any infringements of patents or other rights of the third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of TOSHIBA or others. 021023_C • The products described in this document are subject to the foreign exchange and foreign trade laws. 021023_E 20 2006-06-14