LM3423MHBSTEVAL National Semiconductor, LM3423MHBSTEVAL Datasheet - Page 3

• Manufacturer Part Number: LM3423MHBSTEVAL
• Description: BOARD, EVALUATION, FOR LM3423MHBST
• Manufacturer: National Semiconductor

Specifications of LM3423MHBSTEVAL

• Kit Contents: LM3423 Assembled Evaluation Board, LM3423 Datasheet, Application Note
• Svhc: No SVHC (15-Dec-2010)
• Kit Features: Cycle-by-Cycle Current Limit, LED Ready Flag, Fault Flag, Programmable

DAP (21)
Pin Descriptions
LM3423
10
11
12
13
14
15
16
17
18
19
20
1
2
3
4
5
6
7
8
9
DAP (17)
LM3421
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
-
-
-
-
COMP
AGND
DDRV
PGND
Name
LRDY
DPOL
GATE
TIMR
nDIM
CSH
RCT
OVP
RPD
HSP
HSN
DAP
FLT
V
V
EN
IS
CC
IN
Thermal PAD on bottom of IC
LED Current Sense Negative
LED Current Sense Positive
Main Switch Current Sense
Resistor Capacitor Timing
Under-Voltage Protection
Internal Regulator Output
Over-Voltage Protection
Main Gate Drive Output
Dim Gate Drive Output
Current Sense High
Resistor Pull Down
LED Ready Flag
Dimming Input /
Analog Ground
Compensation
Power Ground
Input Voltage
Description
Dim Polarity
Fault Timer
Fault Flag
Enable
3
Bypass with 100 nF capacitor to AGND as close to the
device as possible in the circuit board layout.
Connect to AGND for zero current shutdown or apply >
2.4V to enable device.
Connect a capacitor to AGND to set the compensation.
Connect a resistor to AGND to set the signal current.
For analog dimming, connect a controlled current
source or a potentiometer to AGND as detailed in the
Analog Dimming section.
External RC network sets the predictive “off-time” and
thus the switching frequency.
Connect to PGND through the DAP copper pad to
provide ground return for CSH, COMP, RCT, and TIMR.
Connect to a resistor divider from V
over-voltage lockout (OVLO). Turn-off threshold is
1.24V and hysteresis for turn-on is provided by 23 µA
current source.
Connect a PWM signal for dimming as detailed in the
PWM Dimming section and/or a resistor divider from
V
Turn-on threshold is 1.24V and hysteresis for turn-off is
provided by 23 µA current source.
Connect to pull-up resistor from VIN and N-channel
MosFET open drain output is high when a fault condition
is latched by the timer.
Connect a capacitor to AGND to set the time delay
before a sensed fault condition is latched.
Connect to pull-up resistor from VIN and N-channel
MosFET open drain output pulls down when the LED
current is not in regulation.
Connect to AGND if dimming with a series P-channel
MosFET or leave open when dimming with series N-
channel MosFET.
Connect to the gate of the dimming MosFET.
Connect to AGND through the DAP copper pad to
provide ground return for GATE and DDRV.
Connect to the gate of the main switching MosFET.
Bypass with 2.2 µF–3.3 µF ceramic capacitor to PGND.
Connect to the drain of the main N-channel MosFET
switch for R
in the source of the same device.
Connect the low side of all external resistor dividers
(V
shutdown.
Connect through a series resistor to the positive side of
the LED current sense resistor.
Connect through a series resistor to the negative side
of the LED current sense resistor.
Star ground, connecting AGND and PGND. For thermal
considerations please refer to
IN
IN
to program input under-voltage lockout (UVLO).
UVLO, OVP) to implement “zero-current”
DS-ON
sensing or to a sense resistor installed
Function
(Note
O
2).
to program output
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