LM3424MH/NOPB National Semiconductor, LM3424MH/NOPB Datasheet - Page 3

• Manufacturer Part Number: LM3424MH/NOPB
• Description: IC LED DVR BUCK/BOOST 20-TSSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: High Power, Constant Currentr

Specifications of LM3424MH/NOPB

• Constant Current: Yes
• Topology: Flyback, PWM, SEPIC, Step-Down (Buck), Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Automotive
• Type - Secondary: High Brightness LED (HBLED)
• Frequency: 2MHz
• Voltage - Supply: 4.5 V ~ 75 V
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• 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: -
• Other names: LM3424MH

DAP
Pin Descriptions
Pin
10
11
12
13
14
15
16
17
18
19
20
1
2
3
4
5
6
7
8
9
TSENSE
SLOPE
TGAIN
COMP
DDRV
Name
TREF
GATE
nDIM
GND
CSH
OVP
HSN
HSP
DAP
V
V
EN
RT
SS
V
IS
CC
IN
S
LED Current Sense Negative
Thermal pad on bottom of IC
LED Current Sense Positive
Dimming Gate Drive Output
Main Switch Current Sense
Temp Foldback Reference
Under-Voltage Protection
Internal Regulator Output
Over-Voltage Protection
Main Gate Drive Output
Temp Foldback Gain
Slope Compensation
Current Sense High
Voltage Reference
Temp Sense Input
Dimming Input /
Resistor Timing
Compensation
Input Voltage
Description
Soft-start
Ground
Enable
Bypass with 100 nF capacitor to GND as close to the device as possible.
Connect to > 2.4V to enable the device or to < 0.8V for low power shutdown.
Connect a capacitor to GND to compensate control loop.
Connect a resistor to GND to set the signal current. Can also be used to analog
dim as explained in the Thermal Foldback / Analog Dimming section.
Connect a resistor to GND to set the switching frequency. Can also be used
to synchronize external clock as explained in the Switching Frequency section.
Connect a PWM signal for dimming as detailed in the PWM Dimming section
and/or a resistor divider from V
Connect a capacitor to GND to extend start-up time.
Connect a resistor to GND to set the foldback slope.
Connect a resistor/ thermistor divider from V
explained in the Thermal Foldback / Analog Dimming section.
Connect a resistor divider from V
2.45V reference for temperature foldback circuit and other external circuitry.
Connect a resistor divider from V
Connect to gate of dimming MosFET.
Connect to DAP to provide proper system GND
Connect to gate of main switching MosFET.
Bypass with a 2.2 µF – 3.3 µF, ceramic capacitor to GND.
Connect to the drain of the main N-channel MosFET switch for R
or to a sense resistor installed in the source of the same device.
Connect a resistor to GND to set slope of additional ramp.
Connect through a series resistor to LED current sense resistor (negative).
Connect through a series resistor to LED current sense resistor (positive).
Connect to GND. Refer to
3
Application Information
(Note
IN
2) for thermal considerations.
S
O
to program input under-voltage lockout.
to set the foldback reference voltage.
to program output over-voltage lockout.
S
to sense the temperature as
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DS-ON
sensing