1. DC/DC Controller for High Current LED Camera Flash BCT 3521Q
BlueChips Technology
A Premier Design Solutions Company…..
DC/DC Controller for
High Current LED Camera Flash BCT 3521Q
Jan2005

2. The Features: BCT 3521Q
Applications: Camera flash in mobile phone, PDAs
Camera flash in low end digital camera
Emergency light, Flash Light
On chip DC/DC converter with current mode control
Maximum continuous DC current: 350mA
Maximum pulsed output current: 450mA
(Duration < 200mS)
Integrated thermal protection circuit
O/P current adjustable by external resistor at pin CS
On Chip Oscillator
Low power consumption
Wide operation temperature: -200C to 700C
Available in QFN16L package (3mm x 3mm)
Jan2005

3. System Advantages: High Output dc current: 350mA
High Output pulsed current: 450mA
Charge Pump vs. PWM controller
One single configuration vs. complicate boost-buck PWM controller.
Advanced Switching Capacitor Technologies
 No external MOSFET/ BJT, Coil-less, no schottky diode, low EMI, in-expensive external components.
Multi source of LEDs
 Current regulator (irrelevant to the LED forward voltage)
High efficiency and lower power consumption
Extend the battery life
Jan2005

4. Camera Phone with LED Flash
Sanyo SCP5300
Motorola V690
Siemens SL65
Sony Ericsson SC003
Jan2005

5. The performance
Without Flash
With Flash
Jan2005

6. BCT3521Q Application One Current Setting
3.6V
Re-chargeable Lithium-ion
Battery
1~10mF
10mF
5, 6
8, 9
10mF
10mF 12
VIN
C2P
C2N
VOUT 2
MCU
BCT3521Q CS
I/O
SHDNB
LED Flash
GND
C1P
C1N
FLASH
1~10mF
LED ON
LED OFF
0.01 ~ 0.2Sec
1 ~ 3 Sec
Jan2005

7. BCT3521Q Application Two Current Settings
3.6V
Re-chargeable Lithium-ion
Battery
1~10mF
10mF
5, 6
8, 9
10mF
10mF 12
VIN
C2P
C2N
VOUT 2
MCU
BCT3521Q CS M1
SHDNB
I/O
ON /OFF
Current 1
Current 2
LED Flash
GND
C1P
C1N
FLASH M2
1~10mF
LED ON
LED OFF
0.01 ~ 0.2Sec
1 ~ 3 Sec
M2 ON
M1 OFF
Jan2005

8. BCT 3511S Status E/S: Available NOW Demo board: Available NOW
Production: Now
Jan2005

9. LED vs Xenon Flash LED Flash Xenon Flash Minimal External Components
I. 2x uF ceramic cap ~US0.01
II. Output Filter capacitor
I. External MOSFET / BJT ? ~US0.12
Volume
1.3mm3
Recycle Time No
3 ~ 4 sec
Resvior capacitor
No need
10uF 10V filter capacitor
0.5 ~ 1.5 mm3
8uF ~ 35uF 330V
Angle of light coverage
20 ~ 25 deg
Thermal Protection
Yes deg C)
May have
EMI Interference
Good, can be used in RF application
Noise
Efficiency
60 ~85 %
75 ~ 85%
Package
SOP14
SOP8
System Cost
$$$
$$$$
Jan2005

10. Flash light Control One shot Flash
Correct exposure value at 2 ~ 6 points
Pre-flash
Continuous Mode
Jan2005

11. Thank You !
Questions & Answer
Jan2005