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TB7100F
Toshiba BiCD Integrated Circuit Silicon Monolithic
TB7100F
Step-down DC-DC Converter IC
The TB7100F is a single-chip step-down DC-DC converter IC. Equipped with a built-in high-speed and low on-resistance power MOSFET, and utilizing a chopper circuit, this IC can achieve a high efficiency in a wide load current range.
Features
* Capable of high current drive (IOUT = maximum of 700 mA), using only a few external components * High efficiency ( = 90% or higher) (@VIN = 5V, VOUT = 3.3V, and IOUT = 300 mA). * Operating voltage (VIN) range: 3 to 5.5 V * Low on-resistance (RDS(ON)): 0.27 (typ.) if VIN = 5 V * High oscillation frequency of 550 kHz (typ.), making it possible to use small external components. * Uses external phase compensation, assuring a high degree of design freedom in selecting external components and determining a loop response. * Employs a current mode architecture with excellent fast load response. * A small surface mount-type ceramic capacitor can be used as an output smoothing capacitor. * Housed in a small surface-mount package (PS-8) with a low thermal resistance. SON8-P-0303-0.65A(PS-8)
Weight: 0.016 g (Typ.)
Pin Assignment
Marking
Part number
COMP
1
8
FB
7100
The dot (*) on the top surface indicates pin 1. *: Lot number
RT
2
7
ENB
PGND
3
6
VIN
SGND
4
5
SW
Due to its MOS structure, this product is sensitive to electrostatic discharge. Handle with care.
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TB7100F
Block Diagram
VIN (pin 6)
ENB (pin 7) RT (pin 2)
Reference voltage supply
1.2 V
Current detection
+
-
Oscillator
Control logic
Driver SW (pin 5) FB (pin 8)
Temperature detection Error amplifier +
Reference voltage (0.8 V) SGND (pin 4) PGND (pin 3) COMP (pin 1)
Pin Descriptions
Pin No. 1 2 3 4 5 6 7 8 Pin Symbol COMP RT PGND SGND SW VIN ENB FB Pin Description Pin for connecting an error amplifier phase compensation resistor and capacitor. Oscillation frequency setting pin for connecting a resistor to the internal oscillation circuit. Connecting 120 k to this pin operates the oscillation circuit at 550 kHz (typ.). Power ground Signal ground Switching pin. A P-channel MOSFET is connected between the VIN and SW pins. The peak switch current corresponding to the voltage that is generated at the COMP pin flows through the power MOSFET. The rating of this peak switch current is 1.0 A (min). Input pin. This pin is placed in the standby state if VENB = low. 1 A or lower operating current Enable pin. This pin is connected to the CMOS inverter. Applying 3.5 V or higher (@ VIN = 5 V) to this pin starts the internal circuit to perform switching control. Output voltage feedback pin. This is connected to the internal error amplifier, which is supplied with a reference voltage of 0.8 V (typ.).
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TB7100F
Timing Chart
OSC 0 IOUT 0 VOUT 0 VCOMP
0
The peak switch current is determined according to the VCOMP.
IL
0
VSW
0
TON T
Overheat state operation
OSC 0
Tch increase
Tch
Hysteresis: 25C (typ.)
VSW
Low Voltage operation
VIN 0 OSC 0 VSW
Hysteresis: 0.1 V (typ)
0 OSC : Internal oscillator output voltage IOUT : Load current VOUT : Output voltage VCOMP : COMP pin voltage IL : Inductor current : SW pin voltage VSW VIN : Input pin voltage Tch : Channel temperature
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Maximum Ratings (Ta = 25C)
Characteristics Input voltage Switch pin voltage Feedback pin voltage Enable pin voltage Input-enable pin voltage Power dissipation (Note 1) Operating temperature Channel temperature Storage temperature Symbol VIN VSW VFB VENB VENB-VIN PD Topr Tch Tstg Rating -0.36 -0.36 -0.36 -0.36 VENB-VIN<0.3 0.7 -4085 150 -55150 Unit V V V V V W C C
Thermal Resistance Characteristic
Characteristics Thermal resistance, channel and ambient (Note 1) Glass epoxy board Material : FR-4 25.4 x 25.4 x 0.8 (Unit: mm) Symbol Rth (ch-a) Max 178.6 (Note 1) Unit C /W
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Electrical Characteristics (unless otherwise specified: Ta = 25C and VIN = 3 to 5.5 V)
Characteristics Operating supply voltage Load current Operating current Standby current Enable pin threshold voltage Enable pin input current Feedback pin current Feedback pin voltage Feedback pin line regulation High-side on-state resistance High-side leakage current Oscillation frequency Error amplifier conductance Peak switch current Undervoltage protection Overheat protection Detection Hysteresis Detection Hysteresis Symbol VIN(OPR) IOUT IIN IIN(STBY) VIH VIL IIH IFB VFB
VFB(LINE)
Test circuit
Test condition
VIN = 5 V, VENB= 5 V, VFB = 0.7 V RT = 120 k VIN= 5 V, VENB= 0 V, VFB = 0.9 V VIN = 5 V VIN = 5 V VIN = 5 V, VENB = 5 V
Min 3 3.5 -1 0.776 1.0 2.3 125
Typ. 5 570 0.8 1.6 0.27 550 800 1.5 2.5 0.1 145 25
Max 5.5 700 750 1 1.5 20 1 0.824 5 0.6 -1 2.7
Unit V mA A A V V A A V mV/V A kHz S

VIN = VENB = 3 V5 V VIN = 5 V, VENB = 5 V, ISW = - 0.5 A VIN = 5 V, VENB = 0 V, VSW = 0 V VIN = 5 V, VENB = 5 V, RT = 120 k VIN = 5 V, VENB = 5 V ICOMP = 20A
RDS(ON) ILEAK fOSC gm ISW(PEAK) VUV VUV TSD TSD
A
V V
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TB7100F
Application Circuit Example
VIN=5V ENB COMP TB7100F RT SGND VIN FB L RFB1 RFB2 VOUT=3.3V CFB
CIN CCOMP2
RCOMP
SW PGND SBD
CCOMP1 GND
RT
COUT GND
Figure 1: TB7100F application circuit example Component constants The following values are given only for your reference and may need tuning depending on your input/output conditions and board layout. CIN: Input smoothing capacitance of 10 F (multilayer ceramic capacitor JMK212BJ106KG, manufactured by Taiyo Yuden Co., Ltd.) COUT: Output smoothing capacitance of 10 F (multilayer ceramic capacitor JMK212BJ106KG manufactured by Taiyo Yuden Co., Ltd.) CCOMP1: Error amplifier phase compensation capacitance of 3300 pF (@ VIN = 5 V, VOUT = 3.3 V, and RT = 120 k) CCOMP2: Error amplifier phase compensation capacitance (not used if phase compensation is possible only with RCOMP and CCOMP1) CFB: Error amplifier phase compensation capacitance (not used if phase compensation is possible only with RCOMP and CCOMP1) RCOMP: Error amplifier phase compensation resistance of 1 k (@ VIN = 5 V, VOUT = 3.3 V, and RT = 120 k) RT: Oscillation frequency setting resistance of 120 k (@ fOSC = 550 kHz) RFB1: Output voltage setting resistance of 75 k (@ VIN = 5 V, VOUT = 3.3 V, and RT = 120 k) RFB2: Output voltage setting resistance of 24 k (@ VIN = 5 V, VOUT = 3.3 V, and RT = 120 k) L: Inductor 6.8 H (@ VIN = 5 V, VOUT = 3.3 V, and RT = 120 k); CDRH4D28C/LD series, manufactured by Sumida Corporation SBD: Schottky barrier diode CRS06 (@ VRRM = 20 V and IF(AV) = 1 A), manufactured by Toshiba Corporation
How to use
Setting the Inductance
The required inductance can be calculated by using the following equation: V VOUT 1 - OUT ... (1) L= VIN fOSC IL
VIN: Input voltage (V) VOUT: Output voltage (V)
fOSC: Oscillation frequency (Hz)
IL: Inductor ripple current (A)
* Generally, IL should be set to 30% to 40% of the peak current flowing through the inductor. For the TB7100F, set IL to 0.3 A, as its peak switch current [ISW(PEAK)] is 1 A (min). Therefore select an inductor whose current rating is no lower than the peak switch current [1 A (min)] of the TB7100F. If the current rating is exceeded, the inductor becomes saturated, leading to an unstable DC-DC converter operation. If VIN = 5 V and VOUT = 3.3 V, the required inductance can be calculated as below. Be sure to select an inductor with an optimum constant by taking VIN variations into consideration.
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L= V 1 - OUT VIN 3.3V 3.3 V = 1 - 550kHz 300mA 5V VOUT fOSC IL
IL 0
IL
= 6.8H
T=
1 fOSC
V TOFF = T 1 - OUT VIN
Figure 2: Inductor current waveform
Setting the output voltage
For the TB7100F, the output voltage is set using the voltage dividing resistors RFB1 and RFB2 according to the reference voltage [0.8 V (typ.)] of the error amplifier connected to the FB pin. If the RFB1 value is extremely large, a delay can occur due to a parasitic capacitance at the FB pin. Keep the RFB1 value within approximately 100 k. The output voltage can be calculated by using equation 2 below. It is recommended that a resistor with a precision of 1% or higher be used for setting the output voltage.
VOUT = VREF (1 + = 0.8 x (1 +
RFB1 ) RFB2
...
SW (2) FB
VOUT RFB1 RFB2
RFB1 ) RFB2
Figure 3: Output voltage setting resistors
Setting the COMP pin for phase compensation
The COMP pin is intended to compensate for any phase delay that may occur inside or outside the TB7100F. Phase compensation is carried out using resistors and capacitors connected to the COMP pin. The constants of the phase compensation components are selected by first specifying RCOMP and CCOMP to be, respectively, 1 k and 3300 pF. However, it is necessary to measure the SW pin oscillation waveform and load response characteristics and tune the component constants, optimizing them so as to optimize the influence of your board layout and component characteristics. When tuning component constants, carefully evaluate them while taking component variations and temperature characteristics into consideration. Table 1 lists the relationships between the RCOMP and CCOMP constants. Use these as a guideline in selecting constants. SW pin waveform stability Decreased Increased Increased Decreased Load response characteristic Increased Decreased Decreased Increased
RCOMP CCOMP
Large Small Large Small
Table 1: Relationships between RCOMP and CCOMP values
Output capacitor
The capacitance of the output ceramic capacitor is greatly affected by temperature. Select a product whose temperature characteristics (such as B-characteristic) are excellent. Set the capacitance to an optimum value that meets the set's ripple requirement and is not lower than 10 F. It is more difficult to achieve phase compensation with ceramic capacitors than with tantalum electrolytic capacitors because the equivalent series resistance (ESR) of the former is much lower than that of the latter. For this reason, perform a careful evaluation when using ceramic capacitors.
Miscellaneous
Generally, a DC-DC converter under current mode control may fail to operate at a constant duty ratio if the duty ratio is 50% or higher. This IC incorporates slope compensation to achieve as stable an operation as possible. However, a delay in the internal circuit may prevent the IC from operating at a constant duty ratio when the duty ratio is 50% or so depending on your input/output and load conditions.
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TB7100F
Board layout
: For the sections shown
FB as solid lines, use thick wires and make them as short as possible.
ENB COMP VIN
VIN
CIN
RCOMP RT
TB7100F
SW PGND
L VOUT SBD RFB1 COUT RFB2 GND
CCOMP
RT
SGND
Figure 4: TB7100F board layout
* For the supply voltage, output, and ground lines, which carry high current, use thick wires and make them as short as possible so as to keep their impedance low. * Place the input/output smoothing capacitors and inductor as close to the IC as possible. * For the output voltage monitoring FB line, keep the wire as short as possible to counter the effects of noise. * Design the layout to ensure that no voltage potential difference occurs between the SGND and PGND pins. Otherwise, the operation of the IC may become unstable. * It is recommended you place the components connected to the COMP and RT pins as close to the IC as possible and ground them at a single point so as stabilize the voltage at these pins. Otherwise, the operation of the IC may become unstable. * The leakage current of the SBD may increase at high temperatures, leading to a thermal runaway. Ensure, therefore, that no problem with the SBD will occur even under the worst-case conditions.
A DC-DC converter using this IC is greatly affected by the characteristics of external components and the impedance of the PCB. Make sure that there is no problem with the dependency of the load current on its output voltage and load response even when any component constant deviates from the corresponding value given above for reference purposes. Also, design the DC-DC converter by selecting optimum external components and a suitable board layout so that no rating of this IC will be exceeded.
Precautions
* If the voltage between the input and output is low, the influence of the on-state voltage of the switch power MOSFET is greater, causing the voltage across the inductor to decrease. For this reason, it may become impossible for the required inductor current to flow, resulting in lower performance or unstable operation of the DC-DC converter. As a rough standard, keep the input-output voltage potential difference at or above 1 V, taking the on-state voltage of the power MOSFET into consideration. * The lowest output voltage that can be set is 0.8 V (typ.). * There is an antistatic diode between the ENB and VIN pins. The voltage between the ENB and VIN pins should satisfy the rating VENB - VIN < 0.3 V
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TB7100F
IIN - VIN
1000
VENB = VIN VFB = 0.7 V RT = 120 k Ta = 25 C
IIN - Ta
1000
VIN = 3 V VENB = 3 V VFB = 0.7 V RT = 120 k
(A)
800
(A) IIN Operating current
4 6 8
800
IIN
600
600
Operating current
400
400
200
200
0 0 2
0 -80 -40 0 40 80 120 160
Input voltage
VIN
(V )
Ambient temperature
Ta
(C)
IIN - Ta
1000
5
VIH, VIL - Ta
(V)
VIN = 3 V 4
(A)
800
IIN
VIH,VIL ENB pin threshold voltage
Operating current
600
3
400
2
VIH
200
VIN = 5.5 V VENB = 5.5 V VFB = 0.7 V RT = 120 k
1
VIL
0 -80 -40 0 40 80 120 160
0 -80 -40 0 40 80 120 160
Ambient temperature
Ta
(C )
Ambient temperature
Ta
(C )
VIH, VIL - Ta
(V)
5
VIN = 5 V
20
IIH - VIN
VIN = 5.5 V Ta= 25C
16
VIH,VIL
4
ENB pin input current
ENB pin threshold voltage
3
VIH
IIH
12
(A)
VIL
2
8
1
4
0 -80 -40 0 40 80 120 160
0 0 2 4 6 8
Ambient temperature
Ta
(C )
Input voltage
VIN
(V )
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TB7100F
IIH - Ta
20
3
VUV - Ta
VUV (V) Undervoltage detection
VIN = 5 V
(A)
VENB= 5V
16
2.8
IIH
ENB pin input current
12
2.6
Return Detection
8
2.4
4
2.2
0 -80 -40 0 40 80 120 160
2 -80 -40 0 40 80 120 160
Ambient temperature
Ta
(C )
Ambient temperature
Ta
(C )
(S)
(S)
gm - VIN
1000
gm - Ta
1000
gm
gm Error amplifier output conductance
800
800
Error amplifier output conductance
600
600
400
400
200 ICOMP=20A Ta = 25 C 0 0 2 4 6 8
200
VIN = 3 V ICOMP=20A
0 -80 -40 0 40 80 120 160
Input voltage
VIN
(V )
Ambient temperature
Ta
(C )
(S)
gm - Ta
()
1000 0.4
RDS(ON) - VIN
ISW = - 0.5 A Ta = 25 C
gm
Error amplifier output conductance
800
RDS(ON) High-side on-resistance
VIN = 5 V ICOMP=20A
0.3
600 0.2
400
0.1
200
0 -80 -40 0 40 80 120 160
0 0 2 4 6 8
Ambient temperature
Ta
(C )
Input voltage
VIN
(V )
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TB7100F
RDS(ON) - ISW
() ()
0.4
VIN = 3 V
RDS(ON) - Ta
0.6
VIN = 5 V ISW = - 0.5 A
RDS(ON)
0.3
RDS(ON) High-side on-resistance
-1.2
5V VENB = VIN Ta = 25 C
0.5
0.4
High-side on-resistance
0.2
0.3
0.2
0.1
0.1
0 0 -0.2 -0.4 -0.6 -0.8 -1
0 -80 -40 0 40 80 120 160
Switch current
ISW
(A )
Ambient temperature
Ta
(C )
VFB - VIN
1
1
VENB = VIN Ta = 25 C
VFB - Ta
VIN = 3 V VENB = VIN
(V)
0.9
(V)
0.9
VFB
Feedback pin voltage
0.7
Feedback pin voltage
0 2 4 6 8
0.8
VFB
0.8 0.7
0.6
0.6
0.5
0.5 -80 -40 0 40 80 120 160
Input voltage
VIN
(V )
Ambient temperature
Ta
(C )
VFB - Ta
1
1000
fOSC - VIN
(kHz)
VIN = 5 V VENB = VIN RT = 120 k Ta = 25 C
(V)
0.9
800
VFB
fOSC
0.7
Feedback pin voltage
Oscillation frequency
0.8
600
400
0.6
200
0.5 -80 -40 0 40 80 120 160
0 0 2 4 6 8
Ambient temperature
Ta
(C )
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TB7100F
fOSC - Ta
1000
10000
fOSC - RT
(kHz)
VIN = 5 V VENB = 5 V VIN = 5V VENB = 5V Ta = 25 C
(kHz) fOSC
800
600
Oscillation frequency
Oscillation frequency
fOSC
1000
400
200
0 -80 -40 0 40 80 120 160
100 10 100 1000
Ambient temperature
Ta
(C )
Oscillation frequency setting resistance
RT
(k )
VOUT - IOUT
1.7 VIN = 3.3 V VOUT = 1.5 V fOSC = 550 kHz L = 4.7 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 1.7 VIN = 5 V VOUT = 1.5 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C
VOUT - IOUT
(V)
(V) VOUT Output voltage
1.6
1.6
VOUT
Output voltage
1.5
1.5
1.4
1.4
1.3 0.001
0.01
0.1
1
1.3 0.001
0.01
0.1
1
Load current
IOUT
(A)
Load current
IOUT
(A)
VOUT - IOUT
2.0 VIN = 3.3 V VOUT = 1.8 V fOSC = 550 kHz L = 4.7 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 2.0
VOUT - IOUT
VIN = 5 V VOUT = 1.8 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C
(V)
1.9
(V)
1.9
VOUT
VOUT Output voltage
1.8 1.7 1.6 0.001
Output voltage
1.7
1.6 0.001
0.01
0.1
1
0.1
1
Load current
IOUT
(A)
Load current
IOUT
(A)
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TB7100F
VOUT - IOUT
2.7 VIN = 5 V VOUT = 2.5 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 3.5 VIN = 5 V VOUT = 3.3 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C
VOUT - IOUT
(V)
(V)
3.4
2.6
VOUT
VOUT Output voltage
3.3 3.2
Output voltage
2.5
2.4
2.3 0.001
0.01
0.1
1
3.1 0.001
0.01
0.1
1
Load current
IOUT
(A)
Load current
IOUT
(A)
- IOUT
100 100
- IOUT
80
80
(%)
(%) Efficiency
60 60
Efficiency
40
20
0 0.001
VIN = 3.3 V VOUT = 1.5 V fOSC = 550 kHz L = 4.7 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 0.01 0.1 1
40
20
VIN = 5 V VOUT = 1.5 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 0.01 0.1 1
0 0.001
Load current
IOUT
(A)
Load current
IOUT
(A)
- IOUT
100 100
- IOUT
80
80
(%)
Efficiency
Efficiency
60
(%)
60
40
20
0 0.001
VIN = 3.3 V VOUT = 1.8 V fOSC = 550 kHz L = 4.7 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 0.01 0.1 1
40
20
0 0.001
VIN = 5 V VOUT = 1.8 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 0.1 1
Load current
IOUT
(A)
Load current
IOUT
(A)
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TB7100F
- IOUT
100 100
- IOUT
80
80
(%)
40
20
0 0.001
VIN = 5 V VOUT = 2.5 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 0.01 0.1 1
Efficiency
Efficiency
60
(%)
60
40
20
0 0.001
VIN = 5 V VOUT = 3.3 V fOSC = 550 kHz L = 6.8 H RCOMP = 1 k CCOMP = 3300pF Ta = 25C 0.01 0.1 1
Load current
IOUT
(A)
Load current
IOUT
(A)
PD - Ta
1
25.4x25.4x0.8mm Refer to Note 1 for the pattern when mounted on a glass epoxy board.
(W) PD Power dissipation
0.8
0.6
0.4
0.2
0 0 40 80 120 160
Ambient temperature
Ta
(C )
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TB7100F
Package dimensions
SON8-P-0303-0.65A Unit: mm
8 5
0.1 max 2.4 0.1 1 0.33 0.05 0.05 M A 4 B 0.05 M B 0.475 0.65 2.8 0.1
0.17 0.02
2.9 0.1
A +0.1 - 0.11 0.8 0.05
S
0.025 S
Weight: 0.016 g (Typ.)
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0.28
+0.1 - 0.11
1.12
+0.13 - 0.12
1.12
+0.13 - 0.12
0.28
TB7100F
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TB7100F
RESTRICTIONS ON PRODUCT USE
* The information contained herein is subject to change without notice.
20070701-EN
* 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. * 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 his document shall be made at the customer's own risk. * 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. * 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 patents or other rights of TOSHIBA or the third parties. * Please contact your sales representative for product-by-product details in this document regarding RoHS compatibility. Please use these products in this document in compliance with all applicable laws and regulations that regulate the inclusion or use of controlled substances. Toshiba assumes no liability for damage or losses occurring as a result of noncompliance with applicable laws and regulations.
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