BD6155FVM
Communication ICs
DC/DC converter for LCD back light
BD6155FVM
BD6155FVM is an ideal IC to drive white LED used for the LCD back light of cellular phones, and PDA etc.
This IC incorporates charging pump step-up circuit to drive white LED with high VF. It also integrates a driver to drive
white LED with 4-step constant current. Only one external resistor can set the current value.
!Applications
Small portable appliances, such as cellular phones, PHS, PDA
Battery-powered equipments using the white LED.
!Features
1) Built-in charging pump step-up circuit.
2) Built-in constant current driver for LED. (Current value : 4 steps variable)
3) Ultra small MSOP8 package. (Height 0.9mm Max.)
!Absolute maximum ratings (Ta=25°C)
Parameter
Symbol
Limits
Unit
Maximum supply voltage
VBAT
−0.3~+6.0
V
Maximum input voltage
VIN
−0.3~+6.0
V
Power dissipation
Pd
350 ∗
mW
Operating temperature
Topr
−25~+75
°C
Storage temperature
Tstg
−55~+125
°C
∗ Reduce to 3.5mW/°C when Ta=25°C or above.
!Recommended operating conditions (Ta=25°C)
Parameter
Power supply
Symbol
Min.
Typ.
Max.
Unit
VBAT
2.9
−
5.5
V
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BD6155FVM
Communication ICs
!Block diagram
1
CURRENT1
CURRENT
CONT
8
VBAT
CHARGE
PUMP
DRIVER
CURRENT2
2
7
C
STBY
3
6
GND
LEDS
4
5
LED
!Pin descriptions
Pin No.
Pin Name
1
CURRENT1
Fixed current setup pin1.
2
CURRENT2
Fixed current setup pin2.
3
STBY
Stand-by pin (High:Operation, Low:No operation)
4
LEDS
LED driver current pin (Fixed current sink pin)
5
LED
LED cathode connection pin for charge pump
6
GND
Ground
7
C
8
VBAT
Function
Capacitor connection pin for charge pump
Power supply voltage input pin
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BD6155FVM
Communication ICs
!Electrical characteristics (unless otherwise noted, Ta=25°C, VBAT=3.6V, STBY=3.6V)
Conditions
Symbol
Min.
Typ.
Max.
Unit
Circuit current
IQ 1
−
0.3
1.0
mA
No load
Standby current
I Q2
−
−
5
µA
No load, STBY=0V
LED max drive current
ILEDMAX
−
−
80
mA
NMOS ON resistance
Ron7
−
3
7
Ω
Current control setup voltage 1
∆VLED1
184
205
226
mV
CURRENT2=High, CURRENT1=High
Current control setup voltage 2
∆VLED2
131
155
179
mV
CURRENT2=High, CURRENT1=LOW
Current control setup voltage 3
∆VLED3
89
105
121
mV
CURRENT2=LOW, CURRENT1=High
Current control setup voltage 4
∆VLED4
42
55
68
mV
CURRENT2=LOW, CURRENT1=LOW
VIH
2.0
−
−
V
VIL
−0.3
−
0.3
V
fosc
−
120
−
kHz
VDC1
4.8
5.6
−
V
VBAT=3.6V, IO=80mA charge pump output monitor RB521-S30 use
VBAT=3.2V, IO=60mA charge pump output monitor RB521-S30 use
Parameter
<LED+Charge pump block>
<Fixed current driver for LED>
Fixed current setup pin Hi
control voltage
Low
Drive current 80mA
<Charge pump>
Oscillator frequency
Output voltage 1
Output voltage 2
4.4
4.8
−
kΩ
RSTBY
250
400
700
Active
VIH
2.0
−
−
V
Stand-by
VIL
−0.3
−
0.3
V
Stand-by pin pull down resistor
Stand-by pin control
voltage
VDC2
V
This product is not designed for protection against radioactive rays.
!Measurement circuit
1µF
1
CURRENT1
VBAT
8
V1 A
A
SWD1
AM8
7
V8
AM1
SW7 1
2
CURRENT2
C+
C1
ON
OPEN
SW72
OPEN
1
7
AM72 A
7
IS72
VM72
F
FM72
D2
3
STBY
GND
6
ON
5
SWD2
OPEN
V3 A
SW52
OPEN
AM3
1
SWO1
OPEN
1
1
4
2
3
V
V72
AM2
SW4
2
D1
2
V2 A
LEDS
LED
3
5
SW5
R=2.7Ω R=20KΩ
OPEN
SWO3
V VM4
VM52
ON
SWO2
ISO1
ON
V
IS52
5
3
SW4B
V52
2
A
ON
C2
2
AM52
V
V
VO1
VA01
AM4 V
Fig.1
3/7
BD6155FVM
Communication ICs
!Circuit operation
1) Charge pump driver
Charge pump is consisted capacitor pin (pin7), external schotky diodes and capacitors.
Output voltage at no loading is 2VBAT-2VF. (VF is as same as schotky’s VF )
Output voltage at loading is referred Fig2. As standard example, however it depends on external components.
15
Charge pump output
(V)
Shotky diodes
RB521-S30
12
OUTPUT VOLTAGE :
VBAT=5.5V
1µF
1µF
VBAT
LED
C (Pin7)
9
VBAT=3.6V
6
VBAT=2.9V
3
0
0
20
40
60
OUTPUT LOAD :
80
100
(mA)
Fig.2 Charge pump loading characteristics
(Typical operating characteristics)
2) Fixed current driver
LED driver fixed current is determined by resistor value between LEDS pin (pin4) and GND.
At current control set up voltage1 (Current1, 2=High) resistor value between LEDS-GND is set as 2.7Ω.
205mV ÷ 2.7Ω = 75.9mA
(2 expressions)
The above current is loaded to LED as fixied current.
LED
LED (5Pin)
+
−
LEDS (4Pin)
CURRENT1
RSENSE
CURRENT2
• LED drive current fix example
LEDS pin voltage
(mV)
LED drive current (mA)
RSENSE=2.7Ω RSENSE=5.1Ω
Current control setup voltage 1 (Current 1=High Current 2=High)
205.0
75.9
40.2
Current control setup voltage 2 (Current 1=Low Current 2=High)
155.0
57.4
30.4
Current control setup voltage 3 (Current 1=High Current 2=Low)
105.0
38.9
20.6
Current control setup voltage 4 (Current 1=Low Current 2=Low)
55.0
20.4
10.8
The less RSENSE, the bigger fixed current for LED drive.
Resistors value should be determined with confirmation of charge pump loading characteristics (Fig.2) and LED's I-V characteristics.
4/7
BD6155FVM
Communication ICs
!Design information
1. The maximum of power loss of this IC is controlled by the output transistor M1 in regulator driver.
Relations of the power supply voltage are signified in 2 expressions with this loss.
∆V = VOUT − (VF2 + ILED × R1 + VLED)
The loss in M1,
∆V × ILED = ILED × {2VBAT− (2VF1 + VF2 + ILED × R1 + VLED)}
(2 expressions)
∆V ; The voltage between LED-LEDS
VF1 ; Shotky’s Di VF
VF2 ; LED’s VF
VOUT ; Charge pump output voltage (Fig.2)
VLED ; The voltage across RSENSE (examples at 205mV calculation)
ILED ; Drive current.
ILED
VF1
VF1
VOUT
VBAT
VF2
LED
R1
LED
∆V
LEDS
M1
RSENS
0.2V
Room temperature power dissipation
(350mW)
Pd-VBAT
Loss Pd : (mW)
300
VF1=0.5V
VF2=3.4V
R1=0Ω
200
IO=50mA
100
IO=80mA
0
2
3
4
5
6
Power supply voltage VBAT (V)
2) Power supply voltage
The thermal shutdown circuit turn on, and output electric current declines when chip temperature is about 125 degrees
due to low electric current driver.
5/7
BD6155FVM
Communication ICs
!Application example
CURRENT1
CURRENT2
1
CURRENT
CONT
8
VBAT
C1
CHARGE
PUMP
DRIVER
1µF
C
2
D1
(RB521S30)
C2
7
1µF
D2
(RB521S30)
STBY
3
6
GND
C3
1µF
LEDS
LED
4
RSENS
2.7Ω
5
VOUT
!Attached components
(1) We recommend capacitor with lower ESR.
(2) We recommend capacitor with is good characteristics to temperature.
(3) Mount all capacitor as close together as possible.
!Operation notes
(1) The notes in power supply turning on.
Turn STBY pin (pin3) in the low state with power supply.
From this sequence, current flowing to the LED terminal is prevented.
(2) Patern layout
Make wiring for power supply, GND and – GND short and thick. Take into considerations the power supply ripple.
A coupling capacitor, which lowers power supply impedance will make it decline.
(3) Though this product is carefully checked for quality assurance, however if it exceeds the absolute maximum rating
such as applied voltage and operating temperature range, this IC may be deteriorated or damaged. One this IC is
damaged, short-circuits and open modes can not be identified. If the usage of the devices involves operations which
will exceed the absolute maximum rating, then it is necessary to take safety measures such as a fuse to protect the
device.
(4) GND
Electric potential as the GND pin must be minimum in any operating condition. Keep the electric potential of the GND
pin below that of the other pins except GND pin in consideration of transient phenomenon.
(5) Thermal design
Be careful to ensure adequate margins for thermal design in consideration of power dissipation (Pd) in actual
operating mode.
(6) Misplacement and short-circuit between pins
When you put the IC on the print-circuit board, please be careful of the direction and correct placement of the IC.
If the IC is placed wrongly, IC may be damaged. And also, the IC may be damaged if an alien substance is mixed into
the line (output-output or output-GND) to be short.
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BD6155FVM
Communication ICs
(7) Operation in the strong electromagnetic field
Please be careful that this IC may be miss operated in the strong electromagnetic field.
100
0.8
80
0.6
0.4
12
VOUT OUTPUT VOLTAGE : VDC (%)
1.0
EFFENCIENCY : η (%)
CIRCUIT CURRENT : IQ1 (mA)
!Electrical characteristic curves
60
40
20
0.2
0.0
0
1
2
3
4
5
0
0
6
10
20
30
40
50
60
70
10
RSENSE=5.1Ω
8
6
BSENSE=2.7Ω
4
BAT
2
0
0
80
CHAGE PUMP OUTPUT CURRENT : IO (mA)
SUPPLY VOLTAGE : VBAT (V)
SUPPLY VOLTAGE : VBAT (V)
Fig.5 Effenciency-load current (note1)
Fig.4 Circuit current-power supply voltage
Fig.6 Charge pump outputpower supply voltage
note1 : Charge pump's characteristic
200
150
100
50
250
0.6
0.5
0.4
0.3
0.2
0.1
RSENSE=0Ω
0
0
1
2
3
4
5
6
0
0
50
100
150
200
LEDS OUTPUT VOLTAGE : VLED (mV)
0.7
LED OUTPUT VOLTAGE : VLED (V)
LEDS OUTPUT VOLTAGE : VLED (mV)
250
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
200
150
100
50
0
0
2
4
STBY PIN CONTROL VOLTAGE : VSTBY (V)
LED INPUT CURRENT : ILED (mA)
SUPPLY VOLTAGE : VBAT (V)
Fig.7 LEDS output voltageSTBY terminal voltage
Fig.8 LED output voltageLED power supply
Fig.9 LEDS output voltagepower supply voltage
6
!External dimensions (Units: mm)
5
1
4
0.29±0.15
0.6±0.2
8
2.8±0.1
4.0±0.2
2.9±0.1
+0.05
0.145−0.03
0.9Max.
0.75±0.05
0.08±0.05
0.475
+0.05
−0.04
0.22
0.65
0.08 M
0.08 S
MSOP8
7/7
Appendix
Notes
No technical content pages of this document may be reproduced in any form or transmitted by any
means without prior permission of ROHM CO.,LTD.
The contents described herein are subject to change without notice. The specifications for the
product described in this document are for reference only. Upon actual use, therefore, please request
that specifications to be separately delivered.
Application circuit diagrams and circuit constants contained herein are shown as examples of standard
use and operation. Please pay careful attention to the peripheral conditions when designing circuits
and deciding upon circuit constants in the set.
Any data, including, but not limited to application circuit diagrams information, described herein
are intended only as illustrations of such devices and not as the specifications for such devices. ROHM
CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any
third party's intellectual property rights or other proprietary rights, and further, assumes no liability of
whatsoever nature in the event of any such infringement, or arising from or connected with or related
to the use of such devices.
Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or
otherwise dispose of the same, no express or implied right or license to practice or commercially
exploit any intellectual property rights or other proprietary rights owned or controlled by
ROHM CO., LTD. is granted to any such buyer.
Products listed in this document use silicon as a basic material.
Products listed in this document are no antiradiation design.
The products listed in this document are designed to be used with ordinary electronic equipment or devices
(such as audio visual equipment, office-automation equipment, communications devices, electrical
appliances and electronic toys).
Should you intend to use these products with equipment or devices which require an extremely high level of
reliability and the malfunction of with would directly endanger human life (such as medical instruments,
transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other
safety devices), please be sure to consult with our sales representative in advance.
About Export Control Order in Japan
Products described herein are the objects of controlled goods in Annex 1 (Item 16) of Export Trade Control
Order in Japan.
In case of export from Japan, please confirm if it applies to "objective" criteria or an "informed" (by MITI clause)
on the basis of "catch all controls for Non-Proliferation of Weapons of Mass Destruction.
Appendix1-Rev1.0