TENTATIVE
TOSHIBA BiCD Digital Integrated Circuit Silicon Monolithic
TB62752AFUG
TB62752AFUG
Step Up Type DC/DC Converter for White LED
Features
The TB62752AFUG is a high efficient Step-Up Type DC/DC
Converter specially designed for constant current driving of White
LED.
This IC can drive 2-8 white LEDs connected series using a Li-ion
battery.
This IC contains N-ch MOS-FET Transistor for Coil-Switching, and
LED Current (I
F
) is set with an external resistor.
This IC is especially for driving back light white LEDs in LCD of PDA,
Cellular Phone, or Handy Terminal Equipment.
Characteristics
•
•
•
•
•
•
•
2-8 white LEDs connected series (Typ. 7LEDs)
Variable LED Current I
F
is set with a external resistor :
20 mA (Typ.) @RSENS = 15
Ω
Output Power : Available for 800mW LED loading
Weight: 0.016 g (Typ.)
High Efficiency : 80% over (Using recommended external parts: Typ. 7LEDs)
Output Over Voltage Shutdown Function :
Switching Operation is shut downed when OVD terminal Voltage is over 37 V (typ.).
IC Package : SSOP6=p=0.95B
Switching Frequency : 1.1 MHz (Typ.)
Pin Assignment
(Top view)
SHDN
FB
W
OVD
GND
VIN
SW
Caution 1:
This IC could be destroyed in some case if amounted in 180° inverse direction.
Please be careful about IC direction in mounting.
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TENTATIVE
Block Diagram
VIN
22µH
TB62752AFUG
SW
OVD
VIN
OSC
PWM
Control
Over Voltage
Detection
(1.1MHz)
Reference
2.2µF
Current
Limit
Error
AMP.
Shutdown
Function
300mV
15Ω
@20mA
GND
FB
1.0µF
SHDN
Pin Function
Pin No.
1
Symbol
SHDN
Function Description
Voltage-Input Terminal for IC-Enable / Disable LED-I
F
.
I
F
adjustment with PWM input signal is also available.
Over Voltage Detection Terminal.
2
3
4
5
6
OVD
VIN
SW
GND
FB
IC Switching Operation is disabled with detection over voltage.
If the voltage returns to detection level or less, Operation is enabled again.
Supply Voltage Input Terminal. ( 2.8V to 5.5V)
Switch Terminal for DC/DC Converter. Nch MOSFET Built-In.
Ground Terminal.
LED I
F
Setting Resister Connecting Terminal.
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TENTATIVE
Absolute Maximum Ratings (Topr = 25°C if without notice)
Characteristics
Power Supply Voltage
Input Voltage
Switching Terminal Voltage
Switching Terminal Current
Power Dissipation
Thermal Resistance
Operation Temperature Range
Storage Temperature Range
Maximum Junction Temperature
Caution 2:
Symbol
VIN
VSHDN
Vo (SW)
Io (SW)
PD
Rth (j-a)
Topr
Tstg
Tj
Ratings
−0.3
to
+6.0
−0.3
to
+VIN +
0.3
-0.3 to 40
1500
0.41 (Device)
0.47 (on PCB) Caution 2
300 (Device)
260 (on PCB)
−40
to
+85
−55
to
+150
150
Unit
V
V
V
mA
W
°C/W
°C
°C
°C
TB62752AFUG
Power Dissipation must be calculated with subtraction of 3.8 mW/°C from Maximum Rating
with every 1°C if T
opr
is upper 25°C. (on PCB)
Recommended Operating Condition
(Ta
=
-40°C to 85°C if without notice)
Characteristics
Power Supply Voltage
LED Current (Average Value)
Symbol
VIN
Io1
-
-
VIN
=
3.6 V, RSENS=15Ω
4LEDs, Topr = 25°C
Test
Circuit
Test Condition
Min
2.8
-
Typ
-
20
Max
5.5
-
Unit
V
mA
Electrical Characteristics
Characteristics
Input Voltage Range
Operating Consumption Current
Quiescent Consumption Current
SHDN Terminal 'H' Level
Input Voltage
SHDN Terminal 'L' Level
Input Voltage
SHDN Terminal Current
Integrated MOS-Tr
Switching Frequency
Switching Terminal Current
Switching Terminal Leak Current
FB Terminal Feedback Voltage
(V
FB
)
FB Terminal Line Regulation
FB Terminal Current
OVD terminal Voltage
OVD Terminal Leakage Current
(Ta
=
25°C, V
IN
=2.8V to 5.5V if without notice)
Symbol
V
IN
I
IN
(On)
I
IN
(Off)
VSHDNH
VSHDNL
I
SHDN
f
OSC
I
oZ
(SW)
I
oz
(SW)
V
FB
∆V
FB
I
oZ
(SW)
V
OVD
I
OVDZ
VIN=3.6V, RSENS=15Ω
VIN=3.6V,V
SHDN
=0V
-
-
VIN=3.6V,V
SHDN
=3.6V
VIN=3.6V,V
SHDN
=3.6V
-
-
V
IN
=3.6V, RSENS=15Ω
T
opr
=25
°
C, L=22µH
V
IN
=3.6V center
V
IN
=3.0 to 5.0V
-
-
V
OVD
=30V
Test Condition
Min
2.8
-
-
1.3
0
-
0.77
-
-
285
-5
-
34.5
-
Typ
-
TBD
0.5
-
-
0
1.1
600
0.5
300
-
TBD
37
0.5
Max
5.5
-
1.0
VIN
0.4
1.0
1.43
-
1
315
5
-
39.5
1
Unit
V
mA
µA
V
V
µA
MHz
mA
µA
mV
%
µA
V
µA
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2005-08-5
TENTATIVE
TB62752AFUG
Protection in LED opened condition
The operation with OVD terminal is available for the protection in case LED Circuit opened.
Please see the example of application circuit.
If load of LED is detached, Nch MOS switching operation is disabled with detection of boost circuit voltage.
Setting of external Capacitor
In case not using PWM signal to SHDN terminal for brightness control, recommended values are
C
1
=
Over 2.2 (µF), C
2
=
Over 1.0 (µF)
In case with PWM signal to SHDN terminal for brightness control, recommended values are
C
1
=
Over 4.7 (µF), C
2
=Under 0.1 (µF) to reduce fluctuation of input current
and up accuracy of brightness.
The recommended capacitor values depend on the Brightness Control Method.
<Please see after page-8>
The capacitor value must be considered for gain enough accuracy of brightness with reduction of noise from
Input current changing.
Setting of I
O
Resistance connects between RSENS pin and GND.
The average current is set by this RSENS value and average current are obtained by the following equation.
I
F
[mA] =
300[mV]
RSENS [Ω]
Current Value error is within ±5%.
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TENTATIVE
Package Dimensions
TB62752AFUG
Weight : 0.016 g (Typcal)
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