LM3404HVMR/NOPB National Semiconductor, LM3404HVMR/NOPB Datasheet - Page 18

• Manufacturer Part Number: LM3404HVMR/NOPB
• Description: IC LED DRVR HP CONST CURR 8-PSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: High Power, Constant Currentr

Specifications of LM3404HVMR/NOPB

• Constant Current: Yes
• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Automotive
• Type - Secondary: High Brightness LED (HBLED), White LED
• Frequency: 1MHz
• Voltage - Supply: 6 V ~ 75 V
• Mounting Type: Surface Mount
• Package / Case: 8-PSOP
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 1A
• Internal Switch(s): Yes
• Efficiency: 96%
• Current, Input Bias: 0.1 μA
• Current, Output: 1.2 A
• Current, Supply: 625 μA
• Package Type: PSOP
• Regulator Type: Buck (Step-Down), Switching
• Temperature, Operating, Range: -40 to +125 °C
• Time, Fall: 20 ns
• Time, Rise: 20 ns
• Voltage, Input: 6 to 75 V
• Voltage, Output: 7 V
• For Use With: 551600000-001A/NOPB - BOARD WEBENCH SO8/SOP LM3404/2LM3404HVEVAL - BOARD EVALUATION LM3404HV
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device
• Other names: LM3404HVMR

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VIN PIN PROTECTION
The VIN pin also has an ESD structure from the pin to GND
with a breakdown voltage of approximately 80V. Any transient
that exceeds this voltage may damage the device. Although
transient absorption is usually present at the front end of a
switching converter circuit, damage to the VIN pin can still
occur.
When V
charge C
circuit board trace inductance as shown in
cited trace inductance then resonates with the input capaci-
tance (similar to an under-damped LC tank circuit) and
causes voltages at the VIN pin to rise well in excess of both
V
IN
and the voltage at the module input connector as clamped
IN
IN
is hot swapped in, the current that rushes in to
up to the V
IN
value also charges (energizes) the
FIGURE 10. VIN Pin with Typical Input Protection
Figure
10. The ex-
18
by the input TVS. If the resonating voltage at the VIN pin ex-
ceeds the 80V breakdown voltage of the ESD structure, the
ESD structure will activate and then “snap-back” to a lower
voltage due to its inherent design. If this lower snap-back
voltage is less than the applied nominal V
nificant current will flow through the ESD structure resulting
in the IC being damaged.
An additional TVS or small zener diode should be placed as
close as possible to the VIN pins of each IC on the board, in
parallel with the input capacitor as shown in
nor amount of series resistance in the input line would also
help, but would lower overall conversion efficiency. For this
reason, NTC resistors are often used as inrush limiters in-
stead.
20205461
IN
voltage, then sig-
Figure
11. A mi-