LM3402/HV 0.5-A Constant Current Buck Regulator for Driving High Power LEDs

1 Features

Integrated 0.5-A N-channel MOSFET
V_IN Range from 6 V to 42 V (LM3402)
V_IN Range from 6 V to 75 V (LM3402HV)
500 mA Output Current Over Temperature
Cycle-by-Cycle Current Limit
No Control Loop Compensation Required
Separate PWM Dimming and Low Power Shutdown
Supports All Ceramic-Output Capacitors and Capacitor-Less Outputs
Thermal Shutdown Protection
VSSOP, SO PowerPAD™ Packages

2 Applications

LED Drivers
Constant Current Source
Automotive Lighting
General Illumination
Industrial Lighting

3 Description

The LM3402/HV are monolithic switching regulators designed to deliver constant currents to high power LEDs. Ideal for automotive, industrial, and general lighting applications, they contain a high-side N-channel MOSFET switch with a current limit of 735 mA (typical) for step-down (Buck) regulators. Hysteretic control with controlled ON-time coupled with an external resistor allow the converter output voltage to adjust as needed to deliver a constant current to series and series - parallel connected arrays of LEDs of varying number and type, LED dimming by pulse width modulation (PWM), broken/open LED protection, low-power shutdown and thermal shutdown complete the feature set.

Device Information⁽¹⁾

PART NUMBER	PACKAGE	BODY SIZE (NOM)
LM3402/HV	VSSOP (8)	3.00 mm × 3.00 mm
LM3402/HV	HSOP (8)	4.89 mm × 3.90 mm

For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Diagram

4 Revision History

Changes from E Revision (April 2013) to F Revision

Added ESD Ratings and Timing Requirements tables, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go

Changes from D Revision (May 2013) to E Revision

Changed layout of National Data Sheet to TI formatGo

5 Pin Configuration and Functions

DGK Package

8-Pin VSSOP

Top View

DDA Package

8-Pin HSOP

Top View

Pin Functions

PIN		I/O	DESCRIPTION
NO.	NAME	I/O	DESCRIPTION
1	SW	O	Switch pin. Connect this pin to the output inductor and Schottky diode.
2	BOOT	O	MOSFET drive bootstrap pin. Connect a 10-nF ceramic capacitor from this pin to SW.
3	DIM	I	Input for PWM dimming. Connect a logic-level PWM signal to this pin to enable and disable the power MOSFET and reduce the average light output of the LED array.
4	GND	—	Ground pin. Connect this pin to system ground.
5	CS	I	Current sense feedback pin. Set the current through the LED array by connecting a resistor from this pin to ground.
6	RON	I	ON-time control pin. A resistor connected from this pin to VIN sets the regulator controlled ON-time.
7	VCC	O	Output of the internal 7-V linear regulator. Bypass this pin to ground with a minimum 0.1-µF ceramic capacitor with X5R or X7R dielectric.
8	VIN	I	Input voltage pin. Nominal operating input range for this pin is 6 V to 42 V (LM3402) or 6 V to 75 V (LM3402HV).
DAP		—	Thermal Pad. Connect to ground. Place 4-6 vias from DAP to bottom layer ground plane.

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)⁽¹⁾⁽²⁾

		MIN	MAX	UNIT
VIN to GND	LM3402	–0.3	45	V
VIN to GND	LM3402HV	–0.3	76	V
BOOT to GND	LM3402	–0.3	59	V
BOOT to GND	LM3402HV	–0.3	90	V
SW to GND	LM3402		–1.5	V
SW to GND	LM3402HV	–1.5		V
BOOT to VCC	LM3402	–0.3	45	V
BOOT to VCC	LM3402HV	–0.3	76	V
BOOT to SW		–0.3	14	V
VCC to GND		–0.3	14	V
DIM to GND		–0.3	7	V
CS to GND		–0.3	7	V
RON to GND		–0.3	7	V
Soldering information	Lead temperature (soldering, 10 s)		260	°C
Soldering information	Infrared/convection reflow (15 s)		235	°C
Junction temperature			150	°C
Storage temperature		–65	125	°C

(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, contact the Texas Instruments Sales Office/ Distributors for availability and specifications.

6.2 ESD Ratings

			VALUE	UNIT
LM3402
V_(ESD)	Electrostatic discharge	Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001⁽¹⁾	±2000	V
V_(ESD)	Electrostatic discharge	Charged-device model (CDM), per JEDEC specification JESD22-C101⁽²⁾	±1000	V
LM3402HV
V_(ESD)	Electrostatic discharge	Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001⁽¹⁾	±2000	V
V_(ESD)	Electrostatic discharge	Charged-device model (CDM), per JEDEC specification JESD22-C101⁽²⁾	±1000	V

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)

		MIN	MAX	UNIT
V_IN	LM3402	6	42	V
V_IN	LM3402HV	6	75	V
Junction temperature		–40	125	°C

6.4 Thermal Information

THERMAL METRIC⁽¹⁾		LM3402, LM3402HV		UNIT
		DDA (HSOP)	DGK (VSSOP)
		8 PINS	8 PINS
R_θJA	Junction-to-ambient thermal resistance	45.6	154.4	°C/W
R_θJC(top)	Junction-to-case (top) thermal resistance	53.1	48.2	°C/W
R_θJB	Junction-to-board thermal resistance	25.8	74.2	°C/W
ψ_JT	Junction-to-top characterization parameter	7.6	4.3	°C/W
ψ_JB	Junction-to-board characterization parameter	25.7	72.9	°C/W
R_θJC(bot)	Junction-to-case (bottom) thermal resistance	3.2	N/A	°C/W

(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

V_IN = 24 V unless otherwise indicated. Typical values apply over –40°C ≤ T_J ≤ 125°C; minimum and maximum values apply over the full operating temperature range ⁽²⁾

PARAMETER		TEST CONDITIONS	MIN	TYP	MAX	UNIT
REGULATION AND OVERVOLTAGE COMPARATORS
V_REF-REG	CS Regulation Threshold	CS Decreasing, SW turns on	194	200	206	mV
V_REF-0V	CS Overvoltage Threshold	CS Increasing, SW turns off		300		mV
I_CS	CS Bias Current	CS = 0 V		0.1		µA
SHUTDOWN
V_SD-TH	Shutdown Threshold	R_ON / SD Increasing	0.3	0.7	1.05	V
V_SD-HYS	Shutdown Hysteresis	R_ON / SD Decreasing		40		mV
OFF TIMER
t_OFF-MIN	Minimum OFF-time	CS = 0 V		300		ns
INTERNAL REGULATOR
V_CC-REG	V_CC Regulated Output		6.6	7	7.4	V
V_IN-DO	V_IN - V_CC Dropout	I_CC = 5 mA, 6 V < V_IN < 8 V		300		mV
V_CC-BP-TH	V_CC Bypass Threshold	V_IN Increasing		8.8		V
V_CC-BP-HYS	V_CC Bypass Hysteresis	V_IN Decreasing		225		mV
V_CC-Z-6	V_CC Output Impedance (0 mA < I_CC < 5 mA)	V_IN = 6 V		55		Ω
V_CC-Z-8		V_IN = 8 V		50		Ω
V_CC-Z-24		V_IN = 24 V		0.4
V_CC-LIM	V_CC Current Limit ⁽¹⁾	V_IN = 24 V, V_CC = 0 V		16		mA
V_CC-UV-TH	V_CC Undervoltage Lock-out Threshold	V_CC Increasing		5.25		V
V_CC-UV-HYS	V_CC Undervoltage Lock-out Hysteresis	V_CC Decreasing		150		mV
V_CC-UV-DLY	V_CC Undervoltage Lock-out Filter Delay	100-mV Overdrive		3		µs
I_IN-OP	I_INOperating Current	Non-switching, CS = 0 V		600	900	µA
I_IN-SD	I_IN Shutdown Current	RON / SD = 0 V		90	180	µA
CURRENT LIMIT
I_LIM	Current Limit Threshold		530	735	940	mA
DIM COMPARATOR
V_IH	Logic High	DIM Increasing	2.2			V
V_IL	Logic Low	DIM Decreasing			0.8	V
I_DIM-PU	DIM Pullup Current	DIM = 1.5 V		75		µA
N-MOSFET AND DRIVER
R_DS-ON	Buck Switch ON Resistance	I_SW = 200 mA, BOOT-SW = 6.3 V		0.7	1.5	Ω
V_DR-UVLO	BOOT Undervoltage Lockout Threshold	BOOT–SW Increasing	1.7	3	4	V
V_DR-HYS	BOOT Undervoltage Lockout Hysteresis	BOOT–SW Decreasing		400		mV
THERMAL SHUTDOWN
T_SD	Thermal Shutdown Threshold			165		°C
T_SD-HYS	Thermal Shutdown Hysteresis			25		°C

(1) V_CC provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading.

(2) Typical specifications represent the most likely parametric norm at 25°C operation.

6.6 Timing Requirements

			MIN	NOM	MAX	UNIT
t_ON-1	ON-time 1, V_IN = 10 V, R_ON = 200 kΩ		2.1	2.75	3.4	µs
t_ON-2	ON-time 2, V_IN = 40 V, R_ON = 200 kΩ	LM3402	490	650	810	ns
t_ON-2	ON-time 2, V_IN = 70 V, R_ON = 200 kΩ	LM3402HV	290	380	470	ns