LM3414MR/NOPB National Semiconductor, LM3414MR/NOPB Datasheet - Page 17
![IC LED DRIVER BUCK 1A 8-PSOP](/photos/13/94/139470/8-epsop_sml.jpg)
LM3414MR/NOPB
Manufacturer Part Number
LM3414MR/NOPB
Description
IC LED DRIVER BUCK 1A 8-PSOP
Manufacturer
National Semiconductor
Series
PowerWise®r
Type
Automotive, High Brightness (HBLED)r
Datasheet
1.LM3414SDNOPB.pdf
(20 pages)
Specifications of LM3414MR/NOPB
Constant Current
Yes
Topology
Low Side, PWM, Step-Down (Buck)
Number Of Outputs
1
Internal Driver
Yes
Type - Primary
Automotive, General Purpose
Type - Secondary
High Brightness LED (HBLED)
Frequency
250kHz ~ 1MHz
Voltage - Supply
4.5 V ~ 42 V
Mounting Type
Surface Mount
Package / Case
8-SOIC (0.154", 3.90mm Width) Exposed Pad
Operating Temperature
-40°C ~ 125°C
Current - Output / Channel
1A
Internal Switch(s)
Yes
Efficiency
96%
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Output
-
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LM3414MR/NOPB
Manufacturer:
NS
Quantity:
285
DESIGN EXAMPLE
Figure 7 shows an example circuit for analog dimming control
using simple external biasing circuitry with a variable resistor.
30124827
FIGURE 7. Example Analog Dimming Control Circuit
In the figure, the variable resistor VR1 controls the base volt-
age of Q1 and eventually adjusts the bias voltage of current
to the IADJ pin (I
). As the resistance of VR1 increases and
EXT
the voltage across VR1 exceeds 1.255V + 0.7V, the LED cur-
rent starts to decrease as I
increases.
EXT
where
The analog dimming begins only when I
> 0.
EXT
DESIGN CONSIDERATIONS
The overall performance of the LED driver is highly depends
on the PCB layout and component selection. To minimize
connection losses and parasitic inductance of the traces, the
best practice is to keep the copper traces connecting the in-
ductor, power switch and rectifier short and thick . Long traces
on critical power paths will introduce voltage and current
spikes to the LM3414/LM3414HV. If the voltage spike level
exceeds the absolute maximum pin voltage of the LM3414, it
could damage the device and LEDs. To avoid physical dam-
age of the circuit, a Transient Voltage Suppressor (TVS) can
be added across VIN and GND pins to suppress the spike
voltage. This also helps in absorbing the input voltage spike
when the circuit is powered through physical switch upon
power up.
17
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