LM3554TME/NOPB National Semiconductor, LM3554TME/NOPB Datasheet - Page 37

• Manufacturer Part Number: LM3554TME/NOPB
• Description: IC LED DVR PHOTO FLASH 16-USMD
• Manufacturer: National Semiconductor
• Type: Photo Flash LED (I²C Interface)r

Specifications of LM3554TME/NOPB

• Constant Current: Yes
• Topology: High Side, Step-Up (Boost)
• Number Of Outputs: 2
• Internal Driver: Yes
• Type - Primary: Flash/Torch
• Type - Secondary: White LED
• Frequency: 2MHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Voltage - Output: 5V
• Mounting Type: Surface Mount
• Package / Case: 16-MicroSMD
• Operating Temperature: -30°C ~ 85°C
• Current - Output / Channel: 600mA
• Internal Switch(s): Yes
• Efficiency: 90%
• Led Driver Application: LED Backlighting, Portable Electronics
• No. Of Outputs: 2
• Output Current: 1.2A
• Input Voltage: 2.7V To 5.5V
• Dimming Control Type: I2C
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM3554TMETR

NTC THERMISTOR PLACEMENT
The termination of the thermistor must be done directly to the
cathode of the Flash LED in order to adequately couple the
heat from the LED into the thermistor. Consequentally, the
noisy environment generated from the switching of the
LM3554's boost converter can introduce noise from GND into
FIGURE 25. Thermistor Voltage Divider and Sensing Circuit
37
the thermistor sensing input. To filter out this noise it is nec-
essary to place a 0.1µF or larger ceramic capacitor close to
the LEDI/NTC pin. The filter capacitor's return must also con-
nect with a low-impedance trace, as close as possible to the
PGND pin of the LM3554.
30042030
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