TOSHIBA BiCD DIGITAL INTEGRATED CIRCUIT SILICON MONOLITHIC

T B 6 2 7 3 2 F U

TOSHIBA

T B 6 2 7 3 2 F U

FEATURE
The TB62732FU is a LED driver by the high efficiency
step up type DC-DC converter that 2-4 serial white LED
can be turned on.
This IC builds in the NchMOS FET transistor to switch
the coil, and builds in the function which derate
the LED current corresponding to the rise in temperature.
And, the average LED current can be set up easily
by the resistance with the outside.
This IC is the most suitable as a driver
of the LED liquid crysta back light of the PDA,
the cellular phone and the the handy terminal.

CHARACTERISTICS
*Maximum output voltage Vo =< 17V
*The variable setup of the average LED current value by
the resistance with the outside.
18 mA (typ) @ R_sens = 2.7 ohms
20 mA (typ) @ R_sens = 2.4 ohms
*Supply electric power
It is turned on to the 320 mW load.
*Compact package
SSOP6 - P - 0.95B ( SOT23-6pin )
*The LED current derating function is built in.
The derating of LED current vs set temperature,
on the automatic operation.
*High efficiency
80% of the efficiency. @ 2-3LEDs turn on. IF=20mA (typ) )
Ron=2.0 ohms (standard) @ Vin = 3.0 - 5.5V
The power MOS transistor building in of low Ron.

*Pin assignment (Top View)

Note 1:
Be careful of handling because there is a terminal which is poor at ESD in this product.

The step up type DC-DC converter only for white LED driver lighting

Weight: 0.016 g (typ)

T B 6 2 7 3 2 F U

SSOP6-P-0.95B

GND

SHDN

GND

VCC

Company Headquarters
3 Northway Lane North
Latham, New York 12110
Toll Free: 800.984.5337
Fax:

518.785.4725

Web: www.marktechopto.com | Email: info@marktechopto.com

California Sales Office:

950 South Coast Drive, Suite 265

Costa Mesa, California 92626

Toll Free: 800.984.5337

Fax: 714.850.9314

Company Headquarters
3 Northway Lane North
Latham, New York 12110
Toll Free: 800.984.5337
Fax:

518.785.4725

Web: www.marktechopto.com | Email: info@marktechopto.com

California Sales Office:

950 South Coast Drive, Suite 265

Costa Mesa, California 92626

Toll Free: 800.984.5337

Fax: 714.850.9314

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

BLOCK DIAGRAM

Name

Function explanation

It is the connection terminal with cathode and IF setup resistance of

LED. It is the feedback terminal of the charge voltage wave form for the
LED current control.

2, 5

GND

It is the ground terminal of the logic part.

SHDN

It is the enable terminal. It becomes the standby mode with "L", and the

LED is turned off. The lighting operation is given with "H".

Vcc

It is the input terminal of the operation voltage for the IC. The operating

voltage is 3.0 to 5.5V.

It is the switch terminal of the coil for the DC/DC converter. The switch is
a Nch MOSFET transistor. This is low Ron.

FIg 1 : BLOCK DIAGRAM

TERMINAL EXPLANATION

Note 2 : Connect all the GND terminals to the ground electric potencial.

0 - 0.12V

OSC

STB

i(sub)

i(add)

1.0MHz

Vcc

GND

SHDN

0.35

GND

REF

Buffer

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

Characteristics

Symbol

Rating

Unit

Supply voltage

Vcc

- 0.3 to + 6.0

Input voltage

Vin

- 0.3 to VCC + 0.3

A(anode) terminal

current

Io(A)

+ 380

A(anode) terminal

voltage

Vo(A)

- 0.3 to + 17

Power dissipation

0.41 ( not on PCB )

0.47 (on PCB) *Note 3

Saturation heat

resistance

Rth(j-a)1

300 ( not on PCB )

degree/W

Rth(j-a)2

260 ( onPCB )

Operation

temperature

Topr

- 40 to + 85

Storage

temperature

Tstg

- 40 to + 150

degree

Maximum juction

temperature

125

Note 3 : When every time the ambient temperature gets over 25 degrees with 1 degree, the

allowable loss must reduce 3.8mW/degree more than maximum rated value. ( When on PCB.)

ABSOLUTE MAXIMUM RATING ( unless otherwised notice Topr = 25 degree )

Characeristics

Symbol

Test condition

min

typ

max

Unit

Supply voltage

Vcc

3.0

4.3

SHDN terminal

H-level input

voltage

VIH

Vcc

-0.5

Vcc

SHDN terminal

L-level input voltage

VIL

0.5

SHDN terminal

"H"level input pulse

width

tpw SHDN

0.5

Setup LED current

(mean)

Maximum step up condition.

Vo (A) is change from 3V to

16V

RECOMMENDED OPERATION CONDITION (unless otherwise notice Topr = -40 to 85 degree)

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

Characteristics

Symbol

Test condition

min

typ

max

Unit

Supply voltage

Vcc

3.0

5.5

Operation supply

current

Icc(On)

Vcc = 3.6V

0.9

Stand-by supply

current

Icc(SHDN)

SHDN = 0 V

0.5

1.2

SHDN terminal

current

I_SHDN

SHDN = Vcc,

built in pull-down resisance

4.2

MOS-Tr on

resistance

Ron

Io(A) <= 380 mA,

detection resistance value is

contained.

2.0

2.5

ohms

MOS-Tr switching

frequency

fOSC

0.7

1.0

1.3

MHz

A terminal voltage

Vo(A)

A terminal current

Io(A)

320

350

380

A terminal

leakage current

Ioz(A)

0.5

Set up LED

current (mean)

Vcc = 3 - 4.3V,

R_sens = 2.7 ohms,

19.6

LED current Vcc

dependence

dIo

L = 6.8uH,

Topr = 25 degree (Note 4)

+/-5

+/-10

Derating start

ambient

temperature

Tdel

R_sens = 2.7 ohms, L = 10uH,

Vo = 16V (Note 5)

degr

ELECTRIC CHARACTERISTICS
( unless otherwised notice, Topr = -40 to 85 degree & Vcc = 3.0 to 5.5 V)

Note 4 : The derating function carries out the measurement in Ta= 25 degree not to work. The

specifications don't contain the dispersion of the R_Sens resistor. Io has the possibility to be different

from the specifications by the inductance value and the relations of the load.
Note 5 : It is a specifications guarantee by the design.

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

BASIC OPERATION

The step up type DC/DC converter is applied, and the basic circuit of the TB62732FU adopts peak control of

the current pulse.

The internal MOS transistor NMOS is turned on in the fixed frequency fOSC =1MHz, and the charge has the

energy in the inductance.

Inductance electric current IL turns off NMOS when it reaches 80% of 1/1MHz when it

increased from IL = 0 and it reached IL = ILpeak = 380 (mA, typ).
The shot key diode is turned on, and IL = Ic2 flows, because the coil may keep IL = ILpeak.

After that, Ic2 is decrease, and become IL = 0.

This operation is repeated, and Ic2 is fully done as to the charge, and it becomes Io, and flows to LED.

The details of a basic pulse to use for the current control are shown in Fig 3.

T = 1/fOSC, fOSC = 1MHz(typ)

Muximum duty 80 %

ILpeak=
380(mA, max)

When fitness inductance

IL = IL peak

When Un-fitness inductance

Fig 3 : the switching wave form of the inductance

Fig 2 : the application circuit (example)

GND

0 - 0.12V

OSC

Buffer

REF

0.35

i(sub)

i(add)

1.0 MHz

R_sens

IL, ILpeak

Ic2

NMOS

6.8 uH

Vcc

SHDN

Vin

STB

IL becomes 0 in the time.

IL doesn't become 0 in the time.

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

Fig 4 : burst control wave form

THE STAE OF THE PEAK CURRENT CONTROL
The peak current control is repeat in the control the waveform which showed it in the Fig 3.
The current pulse of the Fig 3 is a charging current on the output capacitor C2.
It is supplied to LED as a discharge current on the output side capacitor, and it through the R_sens to GND.
And, as for the charging voltage waveform of the output capacitor C2, it returns in the IC from the K terminal.
The internal circuit which the K terminal should be input from controls the current pulses so that the
average voltage value of the voltage wave form which it could get may become 53 mV (typ).
The constant current is controlled as a result as an average electric current value. Therefore, when R_sens = 2.7
ohm is connected, the average current value of (53 mV /2.7 ohms) = 19.6 mA can get it.

This IC is designed for the purpose of supplying the power 320 mW (min).
Generally it is a step up inductance 6.8 uH to the load power 320 mW. And, when the load electric power is small, it
can be done small for the inductance.

As a condition about the LED load between the generator terminal and the K terminal,
Please keep the condition in Vin (Vcc) < LED VF total.
There are no relations with the control of the IC, and LED is always turned on.

STANDBY MODE OPERATION
The SHDN terminal set-up the normal operation and the standby operation. The lighting operation is possible in
the "L" level in the stop (at the standby mode), the "H" level. Still, consumption supply current in the standby mode
is 1.2uA (max).

A-terminal voltage

A-terminal current
(External inductor current)

K-terminal voltage
(Waveform of current for cap. charge)

Maximum On pulse
width = 85%

I A( peak )

LED Vf

Switching frequency fOSC = 1MHz

It stabilizes it in the set Io
with lowering IA (peak).

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

THE SETUP ON THE OUTPUT SIDE CAPACITOR
The C2 is upper 0.47(uF) above is recommended from the consideration to the IF peak.

THE SETUP ON THE INDUCTANCE
The minimum inductance with the outside is calculated with the next formula.

L(uH) = ((K*Po)-Vin min.*Io)*(1/fOSC min.)*2*(1/(Ip min.*Ip min.)) - - - Form 2

Each clause is as mentioned in the following.
Po (W) : output power (the electric energy which should be necessary the LED load)
Po (W) = (VF LED*IF LED)+(Vf schottky*IF LED)+(R_sens*IF LED*IF LED)
( Forward current of LED is IF LED (mA) = Setup currnet Io (mA), Forward voltage of LED is VF LED (V),
Forward voltage of schottky diode is VF schottky (V), Setup resistance of output currnet is R_sens (ohms) )

Vin min (V) : Minimum input voltage(battely voltage)
When there is a resistance element on the input voltage side, that one for the voltage descent is taken into
consideration to the minimum input voltage.
The input Iin is estimated roughly in Form 3.

Iin (mA) = Vo / Vin * IF --- Form 3

Example, the voltage drop of 1(V) occurs when it becomes Iin = 0.1(A) and has the line resistance of
1 (ohms).
At this time, Vin=3.1 (V) becomes minimum Vin value because the minimum Vcc specifications of spec
is Vcc=3.0 (V).

Io (A) : The average current value established with R_sens. Show the fig-5 on next page.

fOSC(Hz) : The switching frequency of the internal MOS transistor.
The specification of fOSC(MHz) = 0.7 min, 1.0 typ and 1.3 max.

Ip (A) : Peak current value to supply to the inductance.
The specification of Ip (mA) = 320 min, 350 typ, 380 max.

For example, the following condition is substituted for the formula.
It is supposed under condition.
Input voltage Vin : Vin=3.0-4.3(V),
Output side capacitance C2 : C2=0.47(uF) - - - C2 is ignored by the calculation.
VF LED = 16(V), schottly diode VF: Vf schottky = 0.3(V),
Setup resistence R_sens : R_sens = 2.7(ohms), Setup current Io : Io = 19.6(mA).

L (uH) = ((16*0.0196+0.3*0.0196+2.7*0.0196*0.0196)-Vin*0.0196)*(1/700e3)*2*(1/(0.32*0.32))

= 7.19(uH, Vin = 3.0V) and 6.59 (uH,Vin = 4.3V)
Therefore, 7.19(uH) in Vcc=3.0V whose input voltage is low is chosen.
It is sufficient by the above calculation on the standard condition.
If the worst case is taken into consideration, the coil of about 1.1 times of the calculation is chosen.

L(uH)=7.19(uH)*1.1 >= 7.90 (uH)

Capacitor C2 (uF)

Ripple current (mA)

Note

0.01

15-25

0.1

5-8

0.47

2-4

Recommend

1-3

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

1.2

1.5

1.8

2.2

2.7

3.3

4.7

5.6

6.8

8.2

9.1

Setup resistance R_sens(ohm)

Setup current ,ho(mA)

4LEDs
add 3LEDs range
add 2LEDs range

Setup current Io vs Setup resistance R_sens

(Typical value. Vcc=3.6V Ta = 25 degree)

CHOICE OF THE R_sens
The resistance R_sens (ohm) in the K terminal - GND is of the outout current Io for the setup.
The average outout current Io(mA) can be set up by a resistance value.

Average setup electric current Io (mA) is estimated roughly in the following.
Io (mA) = 53(mV) / R_sens (ohm)

For example, R_sens = 2.7 (ohm) becomes Io = 19.6 (mA).
The absolute value accuracy of the current is to take the +/-12 percent into consideration.
(The accuracy of R_sens isn't contained.)

When 320 (mW) is output, this IC recommends L=10 (uH).
Example, when the output power gets over 320 (mW), the setup current Io has the possibility that Io
doesn't meet the set point.

And, this IC can get the setup current Io even if the output side capacitor C2 isn't connected.
In this case, be careful in the rush current IFP (mA) to LED because the LED current becomes the pulse
current of the maximum peak magnitude 380 (mA).
Shortening circuit board wiring by using the part whose reactance element is small as much as possible is
recommended with the R_sens resistor.
And, mounting it near here as much as possible is recommended with each part in application circuit
as well.

Fig 5 : The graph of the setup current Io and the setup resistance R_sens

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

ABOUT THE CURRENT DERATING FUNCTION

As for the LED current, generally the current derating recommended against the rise in the ambient temperature.

The TB62732FU aims at turning on white LED of the back light illuminant of the color LCD safely and efficiently,

and builds in the current derating function which set temperature was presumed.

This IC has the character which makes the current 100(%) in the case of Tjs=45 (degree) and which makes

the current 0(%) again in the case of Tjs=100 (degree) corresponding to internal detection temperature Tjs.

When it is seen from set temperature Ta (degree), the temperature that self-fever temperature Tup (degree)

in the operation was reduced from Tjs = 45 (degree) becomes a starting temperature Ts (degree).

Starting temperature Ts (degree) = 45 (degree) - self-fever temperature Tup (degree) --- Form 4

Therefore, the derating character functions as the figure 6, and shows internal detection temperature Tjs and

the rate of change of the outout current.

Self-fever temperature Tup (degree) in the operation is calculated with the Form 5.

Self-fever temperature Tup (degree) ---- ceremony 5

= (P loss (W) - P parts(W))*Rth(j-a) (degree/W)

It is described in the following about each clause.

DC resistance of the inductance : RDC(ohm), Forward current of LED : IF LED(A),

Total forward voltage of LED : VF LED(V), Forward voltage : VF schottky(V),

Setup resistance : R_sens(ohm), Power loss of lighting circuit : P loss(W)=(Po/efficiency)-Po(W),

Power loss of parts : P parts(W)=RDC*Iin+VF schottky*IF LED+R_sens*IF LED*IF LED,

Saturation thermal resistance of package :

Rth(j-a) (degree/W) =< 260 - - - when on board, muximum

Output power :

Po(W) = VF LED*Io(A)

Input power :

Pi(W) = Vin (V)*Iin(A)

Efficiency :

Efficiency(%)=100*(Po/Pi)

Example : When the measurement of the lighting circuit tightened each following value.

RDC=0.5(ohm), Po=320(mW), Iin=0.1(A), Io=20(mA), R_sens=1.8(ohm), VF schottky=0.3(V),

Efficiency=70(%)

In this case, self-fever temperature Tup

Tup (degree)= ((0.32-(0.32*0.7))-(0.5*0.1+0.3*0.0196+2.7*0.0196*0.0196))*260 =10.16 (degree)

Start temperatue Ts(degree)=45(degree)-10.16(degree)=33.4(degree)

Io is controlled as the Fig 6 as a result within the recommendation current area of LED.

The saturation thermal resistance Rth(j-a) = 260 (degree /W) is maximum value. They sometimes become

the Rth(j-a) = 210 - 260 (degree /W) by mounting.

And, the individual difference is formed in the starting temperature with the character of the IC and the influence

of the difference in the environment of the use.

Fig 6 : the derating function of the setup current

100

Ts/Tjs (degree)

100

120

Rate of the Outout Current.

The change of
Ts=34.4(degree)
(20mA=100%)
The
recommendation
current area of LED
(25mA conversion)
The change by Tjs

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

Application evaluation circuit example 1

(The evaluation result example by the small coil. : Coil = LDR304612T-6R8)

6.8uH is the most suitable when serial 3-4LED are turned on by IF= 20m A.

4.7uH is recommended when serial 2LED is turned on steadily in the range of VIN>4.5V.

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

4LED Efficiency

4LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

3LED Efficiency

3LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

2LED Efficiency

2LED IF

Vin - Efficiency/IF

6.8uH

S-Di

VIN

3.2-4.2V

2.2uF

0
.
47

OFF

R_SENS

2.6

L1:

TDK LDR304612T-6R8

S-Di: TOSHIBA

1SS404

20V/1A

LED:

NICHIA NSCW215T

2-4LEDs

0.01uF

VCC

SHDN

GND

Efficiency

(%)

Ave Efficiency(%)

2LED

79.0-83.8

81.6

3LED

75.1-80.9

78.3

4LED

72.0-78.3

75.7

IF (mA)

Vcc dependence

(%)

2LED

19.5-21.1

7.8

3LED

19.5-20.5

4.9

4LED

19.6-20.7

5.3

The efficiency of the VIN=3.0-4.3V range

The IF of the VIN=3.0-4.3V range

Note : The value is our company actual measurement value.

The result has the possibility to be different by the measurement

environment.

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

Application evaluation circuit example 2

(The evaluation result example by the small coil. : Coil = CXML321610-7R0)

6.8uH is the most suitable when serial 3-4LED are turned on by IF= 20m A.

4.7uH is recommended when serial 2LED is turned on steadily in the range of VIN>4.5V.

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

4LED Efficiency

4LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

3LED Efficiency

3LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

2LED Efficiency

2LED IF

Vin - Efficiency/IF

6.8uH

S-Di

VIN

3.2-4.2V

2.2uF

0
.
47

OFF

R_SENS

2.6

L1:

SUMITOMO CXML321610-7R0

S-Di:

TOSHIBA 1SS404 20V/1A

LED:

NICHIA NSCW215T

2-4LEDs

0.01uF

VCC

SHDN

GND

Efficiency

(%)

Ave Efficiency(%)

2LED

78.2-84.1

81.3

3LED

72.0-79.1

75.8

4LED

66.9-71.1

74.6

IF (mA)

Vcc dependence

(%)

2LED

19.8-21.6

8.1

3LED

20.0-21.0

4.8

4LED

20.4-21.5

4.9

The efficiency of the VIN=3.0-4.3V range

The IF of the VIN=3.0-4.3V range

Note : The value is our company actual measurement value.
The result has the possibility to be different by the measurement
environment.

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

Application evaluation circuit example 3

(The evaluation result example by the small coil. : Coil = 976AS-6R8)

6.8uH is the most suitable when serial 3-4LED are turned on by IF= 20m A.

4.7uH is recommended when serial 2LED is turned on steadily in the range of VIN>4.5V.

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

4LED Efficiency

4LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

3LED Efficiency

3LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

2LED Efficiency

2LED IF

Vin - Efficiency/IF

6.8uH

S-Di

VIN

3.2-4.2V

2.2uF

0
.
47u

OFF

R_SENS

2.6

L1:

TOKO 976AS-6R8

S-Di: TOSHIBA

1SS404

20V/1A

LED:

NICHIA NSCW215T

2-4LEDs

0.01uF

VCC

SHDN

GND

Efficiency

(%)

Ave Efficiency(%)

2LED

79.7-84.4

82.3

3LED

76.7-82.1

79.5

4LED

73.1-79.7

74.0

IF (mA)

Vcc dependence

(%)

2LED

19.4-21.1

8.1

3LED

19.5-20.5

5.1

4LED

19.6-20.7

5.3

The efficiency of the VIN=3.0-4.3V range

The IF of the VIN=3.0-4.3V range

Note : The value is our company actual measurement value.

The result has the possibility to be different by the measurement
environment.

TOSHIBA

T B 6 2 7 3 2 F U

27, Feb 2002 (Ver.04)

Application evaluation circuit example 4
(The evaluation result example by the small coil. : Coil = CXLD140-6R8)

6.8uH is the most suitable when serial 3-4LED are turned on by IF= 20m A.
4.7uH is recommended when serial 2LED is turned on steadily in the range of VIN>4.5V.

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

4LED Efficiency

4LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

3LED Efficiency

3LED IF

Vin - Efficiency/IF

3.2

3.4

3.6

3.8

4.2

Vin (V)

LED Current IF (mA)

Efficiency (%)

2LED Efficiency

2LED IF

Vin - Efficiency/IF

6.8uH

S-Di

VIN

3.2-4.2V

2.2uF

0
.
47uF

OFF

R_SENS

2.6

L1:

SUMITOMO CXLD140-6R8

S-Di: TOSHIBA

1SS404

20V/1A

LED:

NICHIA NSCW215T

2-4LEDs

0.01uF

VCC

SHDN

GND

Efficiency

(%)

Ave Efficiency(%)

2LED

80.3-84.9

82.9

3LED

77.2-82.8

80.2

4LED

74.1-80.4

77.6

IF (mA)

Vcc dependence

(%)

2LED

19.4-21.0

7.6

3LED

19.5-20.5

5.1

4LED

19.6-20.7

5.3

The efficiency of the VIN=3.0-4.3V range

The IF of the VIN=3.0-4.3V range

Note : The value is our company actual measurement value.
The result has the possibility to be different by the measurement

environment.

Электронный компонент: TB62732FU