Texas Instruments Incorporated AN-1986 User's Guide
VIN (V)
EFFICIENCY (%)
10 15 20 25 30
100
95
90
85
80
1 Introduction
This evaluation board showcases the LM3429 NFET controller used with a boost current regulator. It is
designed to drive 9 to 12 LEDs at a maximum average LED current of 1A from a DC input voltage of 10 to
26V.
The evaluation board showcases most features of the LM3429 including PWM dimming, overvoltage
protection and input under-voltage lockout. It also has a right angle connector (J7) which can mate with an
external LED load board allowing for the LEDs to be mounted close to the driver. Alternatively, the LED+
and LED- banana jacks can be used to connect the LED load.
The boost circuit can be easily redesigned for different specifications by changing only a few components
(see Alternate Designs ). Note that design modifications can change the system efficiency for better or
worse. See the LM3429 LM3429Q1 N-Channel Controller for Constant Current LED Drivers (SNVS616)
data sheet for a comprehensive explanation of the device and application information.
User's Guide
SNVA404B–July 2009–Revised May 2013
AN-1986 LM3429 Boost Evaluation Board
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SNVA404B–July 2009–Revised May 2013 AN-1986 LM3429 Boost Evaluation Board
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Figure 1. Efficiency with 9 Series LEDS AT 1A
1
Copyright © 2009–2013, Texas Instruments Incorporated
D1
OVP
LM3429
nDIM
PGND
NC
DAP
GATE
COMP
CSH
RCT
IS
HSN
HSP
L1
C9
R6
Q1
R1
C7
R13
R5
1
2
3
4
5
6
7
14
13
12
11
10
9
8
R7
R8
AGND
R10
Q3
R4
PWM
R18
R11
R9
R20
C12
V
IN
V
CC
V
IN
GND
V
IN
C8
R2
R3
C1
C2, C3,
C16, C18
C4, C6,
C17, C19
R12
TP7
TP10
TP1
TP11
TP12
J1
J2
U1
LED-
1
2
3
5
6
7
14
13
12
10
9
8
J7
4 11
J5
TP3
TP2
LED+
J4
Schematic
2 Schematic
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2
Figure 2. Board Schematic
AN-1986 LM3429 Boost Evaluation Board SNVA404B–July 2009–Revised May 2013
Copyright © 2009–2013, Texas Instruments Incorporated
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3 Pin Descriptions
Pin Name Description Application Information
1 V
2 COMP Compensation Connect a capacitor to AGND.
3 CSH Current Sense High dimming, connect a controlled current source or a potentiometer
4 RCT Resistor Capacitor Timing
5 AGND Analog Ground
6 OVP Over-Voltage Protection voltage lockout (OVLO). Turn-off threshold is 1.24V and
7 nDIM Not DIM input
8 NC No Connection Leave open.
9 PGND Power Ground
10 GATE Gate Drive Output Connect to the gate of the external NFET.
11 V
12 IS Main Switch Current Sense R
13 HSP
14 HSN
DAP Star ground, connecting AGND and PGND.
(15)
IN
CC
DAP Thermal pad on bottom of IC
Pin Descriptions
Input Voltage
Internal Regulator Output Bypass with a 2.2 µF–3.3 µF, ceramic capacitor to PGND.
High-Side LED Current Sense Connect through a series resistor to the positive side of the LED
Positive current sense resistor.
High-Side LED Current Sense Connect through a series resistor to the negative side of the
Negative LED current sense resistor.
Bypass with 100 nF capacitor to AGND as close to the device as
possible in the circuit board layout.
Connect a resistor to AGND to set the signal current. For analog
to AGND as detailed in the Analog Dimming section.
Connect a resistor from the switch node and a capacitor to
AGND to set the switching frequency.
Connect to PGND through the DAP copper circuit board pad to
provide proper ground return for CSH, COMP, and RCT.
Connect to a resistor divider from VOto program output overhysteresis for turn-on is provided by 20 µA current source.
Connect a PWM signal for dimming as detailed in the PWM
Dimming section and/or a resistor divider from VINto program
input under-voltage lockout (UVLO). Turn-on threshold is 1.24V
and hysteresis for turn-off is provided by 20 µA current source.
Connect to AGND through the DAP copper circuit board pad to
provide proper ground return for GATE.
Connect to the drain of the main N-channel MosFET switch for
sensing or to a sense resistor installed in the source of
DS-ON
the same device.
4 Bill of Materials
Qty Part ID Part Value Manufacturer Part Number
2 C1, C4 0.1 µF X7R 10% 100V TDK C2012X7R2A104K
4 C2, C3, C16, C18 4.7 µF X7R 10% 100V MURATA GRM55ER72A475KA01L
3 C6, C17, C19 2.2 µF X7R 10% 100V TDK C4532X7R2A225K
1 C7 1000 pF COG/NPO 5% 50V MURATA GRM2165C1H102JA01D
1 C8 1 µF X7R 10% 16V MURATA GRM21BR71C105KA01L
1 C9 2.2 µF X7R 10% 16V MURATA GRM21BR71C225KA12L
1 C12 0.1 µF X7R 10% 25V MURATA GRM21BR71E104KA01L
1 D1 Schottky 100V 12A VISHAY 12CWQ10FNPBF
4 J1, J2, J4, J5 banana jack KEYSTONE 575-8
1 J7 2 x 7 shrouded header SAMTEC TSSH-107-01-SDRA
1 L1 33 µH 20% 6.3A COILCRAFT MSS1278-333MLB
1 Q1 NMOS 100V 40A VISHAY SUD40N10-25
1 Q3 NMOS 60V 260 mA ON-SEMI 2N7002ET1G
1 R1 12.4 kΩ 1% VISHAY CRCW080512k4FKEA
1 R2 0Ω 1% VISHAY CRCW08050000Z0EA
2 R3, R20 10Ω 1% VISHAY CRCW080510R0FKEA
SNVA404B–July 2009–Revised May 2013 AN-1986 LM3429 Boost Evaluation Board
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Copyright © 2009–2013, Texas Instruments Incorporated
3
Bill of Materials
1 R4 16.9 kΩ 1% VISHAY CRCW080516k9FKEA
1 R5 1.43 kΩ 1% VISHAY CRCW08051k43FKEA
1 R6 0.04Ω 1% 1W VISHAY WSL2512R0400FEA
2 R7, R8 1.0 kΩ 1% VISHAY CRCW08051k00FKEA
1 R9 0.1Ω 1% 1W VISHAY WSL2512R1000FEA
1 R10 35.7 kΩ 1% VISHAY CRCW080535k7FKEA
1 R11 15.8 kΩ 1% VISHAY CRCW080515k8FKEA
2 R12, R13 10.0 kΩ 1% VISHAY CRCW080510k0FKEA
1 R18 750 kΩ 1% VISHAY CRCW0805750kFKEA
7 TP1, TP2, TP3, TP7, turret KEYSTONE 1502-2
1 U1 Buck-boost controller TI LM3429
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TP10, TP11, TP12
4
AN-1986 LM3429 Boost Evaluation Board SNVA404B–July 2009–Revised May 2013
Copyright © 2009–2013, Texas Instruments Incorporated
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