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LM3554 -
1.2A Dual Flash LED Driver System with I2C Compatible Interface
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Features
| • | Dual High Side Current Sources |
| • | Grounded Cathode Allowing for Better Heatsinking and LED Routing |
| • | >90% Efficiency |
| • | Ultra-Small Solution Size: < 23mm2 |
| • | Four Operating Modes: Torch, Flash, LED Indicator and Voltage Output |
| • | Accurate and Programmable LED Current from 37.5mA to 1.2A |
| • | Programmable 4.5V or 5.0V Constant Output Voltage |
| • | Hardware Flash and Torch Enable |
| • | LED Thermal Sensing and Current Scaleback |
| • | Software Selectable Input Voltage Monitor |
| • | Programmable Flash Timeout |
| • | Dual Synchronization Inputs for RF Power Amplifier Pulse Events |
| • | Open and Short LED Detection |
| • | Active High Hardware Enable for Protection Against System Faults |
| • | 400kHz I
2C Compatible Interface
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| • | 16-Bump (1.7mm × 1.7mm × 0.6mm) µSMD |
General Description
The LM3554 is a 2 MHz fixed frequency, current mode synchronous boost converter. More...
Applications
| • | Camera Phone LED Flash Controller |
| • | Class D Audio Amplifier Power |
| • | LED Current Source Biasing |
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Typical Application
click for larger image
Typical application circuit
| Parameters | Values |
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| Regulated LEDs |
11, 2 |
| Total LED Current |
30, 1200 mA |
| Boost Type |
Inductive |
| Switching Frequency |
2000, 500 kHz |
| Efficiency (peak) |
90, 95 % |
| Input Min Voltage |
2.7 Volt |
| Input Max Voltage |
5.5 Volt |
| LED Configuration |
Series, Parallel |
| Current Matching |
0.5%, Perfect |
| OutputMax Voltage |
5.4, 40 Volt |
| Supply Current |
2.7, 1.35 mA |
| Switching Type |
Fixed Freq |
| Special Features |
Indicator, LED Temp Sense, VOUT Mode, I2C Compatible Interface, Dual TX Interrupt, VIN Monitor, Fault Detection, Programmable Current Limit, I2C Compatible Interface, Dual Ambient Light Current Control, 10 bit current control, Internal Ambient Light Sensing Diode Resistors, Drives 2 to 11 Series White LEDs, 1000:1 Dimming Ratio, Programmable Ramp Rates |
| PWM BrightCtrl |
No, Yes |
| Analog-V BrightCtrl |
No |
| Ambient Light Compensation |
No, Yes |
| RGB-LED |
No |
| Temperature Min |
-30 deg C |
| Temperature Max |
+85 deg C |
| RegType |
Switching Regulator |
| PowerWise |
No, Yes |
Additional Resources
Application Notes
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Datasheet
RoHS Compliance Information
| Size in Kbytes | Date |
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| LM3554 PRODUCT BRIEF Synchronous Boost Converter with 1.2A Dual High Side LED Drivers and I 2 C Compatible Interface |
148
Kbytes |
8-Jun-09 |
Download |
Package Availability, Models, Samples & Pricing
General Description
The LM3554 is a 2 MHz fixed frequency, current mode synchronous boost converter. The device is designed to operate as a dual
600mA (1.2A total) constant current driver for high current white LEDs, or as a regulated 4.5V or 5V voltage source.
The dual high side current sources allow for grounded cathode LED operation. An adaptive regulation method ensures the current
source for each LED remains in regulation and maximizes efficiency.
The main features include: an I
2C compatible interface for controlling the LED current or the desired output voltage, a hardware Flash enable input for direct
triggering of the Flash pulse, and dual TX inputs which force the Flash pulse into a low current Torch mode allowing for synchronization
to RF power amplifier events or other high current conditions. Additionally, an active high hardware enable (HWEN) input provides
a hardware shutdown during system software failures.
Five protection features are available within the LM3554 including a software selectable input voltage monitor, an internal
comparator, for interfacing with an external temperature sensor, four selectable current limits to ensure the battery current
is kept below a predetermined peak level, an over-voltage protection feature to keeps the output voltage below the OVP threshold
in case of an open LED, and an output short circuit protection which limits the output current during an output short to GND.
Additionally, the device provides various fault indicators including: a thermal fault flag indicating the LED temperature
has tripped the thermal threshold, a flag indicating a TX event has occured, a flag indicating the flash timeout counter
has expired, a flag indicating the devices die temperature has reached the thermal shutdown threshold, and a flag indicating
an open or short LED.
Notice: This document is not a full datasheet. For more imformation regarding this product, or to order samples, please contact
your National Semiconductor sales office or visit http://www.national.com/support/dir.html.
Reliability Metrics
| Part Number |
Process |
EFR Reject |
EFR Sample Size |
PPM |
LTA Rejects |
LTA Device Hours |
FITS |
MTTF (Hours) |
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LM3554TME | CMOS7 | 0 | 18406 | 0 | 0 | 1089000 | 4 | 309006723
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LM3554TMX | CMOS7 | 0 | 18406 | 0 | 0 | 1089000 | 4 | 309006723
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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 |
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| 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
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208 Kbytes |
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| 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]
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