TOSHIBA TB62731FUG

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
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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.
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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)
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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.
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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
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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.
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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.
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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).
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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
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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
(%)
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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
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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)
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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)
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TB62731FUG
Package Dimensions
Weight: 0.016 g (typ.)
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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.
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(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.
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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.
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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
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