LM3406_15 datasheet(24/38 Pages) TI1

Part #	LM3406

Description	Constant Current, Buck Regulator for Driving High Power LEDs

Download	38 Pages

Scroll/Zoom	100%

Manufacturer	TI1 [Texas Instruments]

Direct Link	http://www.ti.com

Logo

24 / 38 page

LM3406, LM3406HV, LM3406HV-Q1

SNVS512E – SEPTEMBER 2008 – REVISED MARCH 2014

www.ti.com

Design Example 1 (continued)

A 2A-rated diode will be used. To determine the proper case size, the dissipation and temperature rise in D1 can

be calculated as shown in the Design Considerations section. VD for a case size such as SMB in a 40V, 2A

Schottky diode at 1.5A is approximately 0.4V and the

θJA is 75°C/W. Power dissipation and temperature rise can

be calculated as:

PD = 1.28 x 0.4 = 512 mW TRISE = 0.51 x 75 = 38°C

(49)

8.3.7 CB, CC AND CF

The bootstrap capacitor CB should always be a 22 nF ceramic capacitors with X7R dielectric. A 25V rating is

appropriate for all application circuits. The COMP pin capacitor CC and the linear regulator filter capacitor CF

should always be 100 nF ceramic capacitors, also with X7R dielectric and a 25V ratings.

8.3.8 EFFICIENCY

To estimate the electrical efficiency of this example the power dissipation in each current carrying element can

be calculated and summed. Electrical efficiency,

η, should not be confused with the optical efficacy of the circuit,

which depends upon the LEDs themselves. One calculation will be detailed for three LEDs in series, where VO =

11.8V, and these calculations can be repeated for other numbers of LEDs.

Total output power, PO, is calculated as:

PO = IF x VO = 1.54 x 11.8 = 18.2W

(50)

Conduction loss, PC, in the internal MOSFET:

PC = (IF

2 x R

DSON) x D = (1.54

2 x 0.75) x 0.5 = 890 mW

(51)

Gate charging and VCC loss, PG, in the gate drive and linear regulator:

PG = (IIN-OP + fSW x QG) x VIN PG = (600 x 10

-6 + 5 x 105 x 9 x 10-9) x 24 = 122 mW

(52)

Switching loss, PS, in the internal MOSFET:

PS = 0.5 x VIN x IF x (tR + tF) x fSW PS = 0.5 x 24 x 1.54 x 40 x 10

-9 x 5 x 105 = 370 mW

(53)

AC rms current loss, PCIN, in the input capacitor:

PCIN = IIN(rms)

2 x ESR = 0.752 0.003 = 2 mW (negligible)

(54)

DCR loss, PL, in the inductor

PL = IF

2 x DCR = 1.542 x 0.06 = 142 mW

(55)

Recirculating diode loss, PD = (1 - 0.5) x 1.54 x 0.4 = 300 mW

Current Sense Resistor Loss, PSNS = 293 mW

Electrical efficiency,

η = PO / (PO + Sum of all loss terms) = 18.2 / (18.2 + 2.1) = 89%

Temperature Rise in the LM3406 IC is calculated as:

TLM3406 = (PC + PG + PS) x θJA = (0.89 + 0.122 + 0.37) x 50 = 69°C

(56)

8.4 Design Example 2

The second example circuit uses the LM3406 to drive a single white LED at 1.5A ±10% with a ripple current of

20%P-P in a typical 12V automotive electrical system. The two-wire dimming function will be employed in order to

take advantage of the legacy 'theater dimming' method which dims and brightens the interior lights of

automobiles by chopping the input voltage with a 200Hz PWM signal. As with the previous example, the typical

VF of a white LED is 3.9V, and with the current sense voltage of 0.2V the total output voltage will be 4.1V. The

LED driver must operate to specifications over an input range of 9V to 16V as well as operating without suffering

damage at 28V for two minutes (the 'double battery jump-start' test) and for 300 ms at 40V (the 'load-dump' test).

The LED driver must also be able to operate without suffering damage at inputs as low as 6V to satisfy the 'cold

crank' tests. A complete bill of materials can be found in Table 2 at the end of this datasheet.

24

Submit Documentation Feedback

Product Folder Links: LM3406 LM3406HV LM3406HV-Q1

Similar Part No. - LM3406_15

Manufacturer	Part #	Datasheet	Description
Cystech Electonics Corp...	LM34063AQ8	301Kb / 9P	DC-to-DC Converter Control Circuit
National Semiconductor ...	LM3406HV	479Kb / 26P	1.5A Constant Current Buck Regulator for Driving High Power LEDs
National Semiconductor ...	LM3406HV	523Kb / 26P	1.5A Constant Current Buck Regulator for Driving High Power LEDs
Texas Instruments	LM3406HV	1Mb / 37P	1.5A Constant Current Buck Regulator for Driving High Power LEDs
National Semiconductor ...	LM3406HVMH	479Kb / 26P	1.5A Constant Current Buck Regulator for Driving High Power LEDs

More results

Similar Description - LM3406_15

Manufacturer	Part #	Datasheet	Description
National Semiconductor ...	LM3406	479Kb / 26P	1.5A Constant Current Buck Regulator for Driving High Power LEDs
	LM3402	560Kb / 24P	0.5A Constant Current Buck Regulator for Driving High Power LEDs
	LM3406	523Kb / 26P	1.5A Constant Current Buck Regulator for Driving High Power LEDs
ON Semiconductor	NCL30160	222Kb / 10P	1.0A Constant-Current Buck Regulator for Driving High Power LEDs January, 2012 ??Rev. 1
Texas Instruments	LM3404	1Mb / 39P	1.0A Constant Current Buck Regulator for Driving High Power LEDs
	LM3402	1Mb / 36P	0.5A Constant Current Buck Regulator for Driving High Power LEDs
	LM3406	1Mb / 37P	1.5A Constant Current Buck Regulator for Driving High Power LEDs
	LM3404	1Mb / 39P	1.0A Constant Current Buck Regulator for Driving High Power LEDs
ON Semiconductor	NCL30161	126Kb / 8P	Constant-Current Buck Regulator for Driving High Power LEDs May, 2013 ??Rev. 0
ON Semiconductor	NCV30161	252Kb / 10P	Constant-Current Buck Regulator for Driving High Power LEDs June, 2019 ??Rev. 1

More results

LM3406 Datasheet(PDF) 24 Page - Texas Instruments

LM3406 Datasheet(HTML) 24 Page - Texas Instruments

Similar Part No. - LM3406_15

Similar Description - LM3406_15

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Datasheet Download

Link URL