LM3424BKBSTEVAL/NOPB National Semiconductor, LM3424BKBSTEVAL/NOPB Datasheet - Page 3

• Manufacturer Part Number: LM3424BKBSTEVAL/NOPB
• Description: BOARD EVAL BUCK BOOST LM3424
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3424BKBSTEVAL/NOPB

• Current - Output / Channel: 1A
• Outputs And Type: 1, Non-Isolated
• Features: Dimmable
• Voltage - Input: 10 ~ 70 V
• Utilized Ic / Part: LM3424
• Core Chip: LM3424
• Topology: Buck-Boost
• No. Of Outputs: 1
• Dimming Control Type: PWM / Analog
• Development Tool Type: Hardware - Eval/Demo Board
• Mcu Supported Families: LM3424 Family
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Other names: LM3424BKBSTEVAL

DAP
LM3424 Pin Descriptions
(21)
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
High-Side LED Current Sense
High-Side LED Current Sense
Thermal pad on bottom of IC
Temperature Foldback Gain
Dimming Gate Drive Output
Main Switch Current Sense
Temperature Sense Input
Internal Regulator Output
Over-Voltage Protection
Temperature Foldback
Slope Compensation
Current Sense High
Voltage Reference
Gate Drive Output
Resistor Timing
Compensation
Not DIM input
Input Voltage
Description
Reference
Soft-start
Negative
Positive
Ground
Enable
Bypass with 100 nF capacitor to GND as close to the device as possible in the
circuit board layout.
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 of the
datasheet.
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
of the datasheet.
Connect a PWM signal for dimming as detailed in the PWM Dimming section
of the datasheet and/or a resistor divider from V
voltage lockout (UVLO). Turn-on threshold is 1.24V and hysteresis for turn-off
is provided by 20 µA current source.
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 of the datasheet.
Connect a resistor divider from V
voltage.
2.45V reference for temperature foldback circuit and other external circuitry.
Connect to a resistor divider from V
(OVLO). Turn-off threshold is 1.24V and hysteresis for turn-on is provided by
20 µA current source.
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 the negative side of the LED current sense
resistor.
Connect through a series resistor to the positive side of the LED current sense
resistor.
Connect to GND and place 6 - 9 vias to bottom layer ground pour.
3
Application Information
S
to set the temperature foldback reference
O
to program output over-voltage lockout
S
to sense the temperature as
IN
to program input under-
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DS-ON
sensing