Datasheet
RoHS Compliance Information
| Size in Kbytes | Date |
 |
| LM3550 PRODUCT BRIEF 5A Flash LED Driver with Automatic Vf and ESR Detection for Mobile Camera Systems |
128
Kbytes |
1-May-09 |
Download |
Package Availability, Models, Samples & Pricing
General Description
LM3550 is a low noise, switched capacitor DC/DC converter designed to operate as a current-limited and adjustable (up to 5.3V)
super-capacitor charger. LM3550 features user selectable super-capacitor charge termination voltages and an optimal charge
termination mode that maximizes flash energy efficiency by accounting for flash element losses. Additionally, the device
provides one adjustable constant-current output (up to 200mA) and one NFET controller ideal for driving one or more high current
LEDs either in a high power Flash mode or a low power Torch mode.
The LM3550 can be configured to utilize a proprietary super-capacitor charging scheme (Optimal Mode), allowing faster charging
times (0 to Target Voltage) and lower current source power dissipation. Optimal Charge mode adapts to changes in the flash
LEDs forward voltage as well as the super-capacitor's ESR ensuring that the super-capacitor is charged to the ideal voltage
required to sustain constant current flash operation.
The LED current and Flash pulse duration of the LM3550 can be programmed via an I
2C compatible interface. The Strobe pin allows the Flash to be toggled via a Flash enable signal from a camera module. The
^EOC pin sinks current when the output voltage reaches 95% of the final value.
The ALD/TEMP input pin allows either a light sensor to adjust the flash current level based on the ambient light conditions,
or it allows for over-temperature detection and protection of the LED during high power operation or high ambient temperature
conditions by connecting an NTC thermistor temperature monitoring circuit to the pin.
Notice: This document is not a full datasheet. For more information regarding this product or to order samples, please contact
your local National Semiconductor sales office or visit http//www.national.com/support/dtr.html.
Reliability Metrics
| Part Number |
Process |
EFR Reject |
EFR Sample Size |
PPM |
LTA Rejects |
LTA Device Hours |
FITS |
MTTF (Hours) |
|
LM3550SP | CMOS7 | 0 | 18406 | 0 | 0 | 1089000 | 4 | 309006723
|
|
LM3550SPX | CMOS7 | 0 | 18406 | 0 | 0 | 1089000 | 4 | 309006723
|
Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR.
The Long Term Failure Rates were calculated
at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress
temperature of 150°C to an application temperature of 55°C.
For more information on Reliability Metrics, please click here.
More Application Notes
| Title | Size in Kbytes |
Date |
|
| AN-1495: Application Note 1495 LM3552 White LED Flash Driver Evaluation Board |
626
Kbytes |
27-Sep-06 |
Download |
AN-1495 (Chinese): Application Note 1495 LM3552 White LED Flash Driver Evaluation Board
|
208 Kbytes |
|
 |
| AN-1780: Application Note 1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface |
1427
Kbytes |
12-Mar-08 |
Download |
[Information as of 7-Nov-2009]
| 
