TS19451 [TSC]

AC/DC WLED Driver with Internal MOSFET Universal Switch Mode; AC / DC WLED驱动器，带有内部MOSFET的通用开关模式


型号：	TS19451
厂家：	TAIWAN SEMICONDUCTOR COMPANY, LTD
描述：	AC/DC WLED Driver with Internal MOSFET Universal Switch Mode AC / DC WLED驱动器，带有内部MOSFET的通用开关模式驱动器开关通用开关
文件：	总7页 (文件大小：152K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

TS19451

AC/DC WLED Driver with Internal MOSFET

Universal Switch Mode

SOT-89

Pin Definition:

1. Drain

2. GND

3. VDD

General Description

The TS19451 is a PWM high efficiency LED driver control IC. It allows efficient operation of LED strings from

voltage source ranging up to 400VDC. It includes an internal high voltage switching MOSFET controlled with fixed

off-time of approximately 10.5µS.

The LED string is driven at constant current, thus providing constant light output and enhanced reliability. The

output current is internally fixed at 50mA. The peak current control scheme provides good regulation of the output

current throughout the universal AC line voltage range of 85~264VAC or DC input voltage of 20~400V

Features

Typical Application Circuit

●

Constant output current at 50mA

Universal 85~264VAC operation

Fixed off-time buck converter

Internal 475V power MOSFET

Application

●

Decorating LED lighting

Lower power lighting fixtures

Back light of flat panel displays

Ordering Information

Part No.

Package

Packing

TS19451CY RMG

SOT-89

1Kpcs / 7” Reel

Note: “G” denotes for Halogen Free

Absolute Maximum Rating

Parameter

Symbol

V_INto GND

I_DD

Limit

~ +475

Unit

Input Voltage Range

Supply Current

ºC

^oC

Power Dissipation @ T_A=25ºC

Operating Ambient Temperature

Storage Temperature Range

Junction Temperature Range

P_D

1300

T_OPR

-40 to +85

-65 to +150

-40 to +150

128

T_STG

T_J

Thermal Resistance – Junction to Ambient

Rθ

^oC/W

Note: Stresses beyond those listed under ”Absolute Maximum Ratings” may cause permanent damage to the

device. These are stress rating only, and functional operation of the device at these or any other conditions beyond

those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum

rating conditions for extended periods may affect device reliability.

1/7

Version: B11

TS19451

AC/DC WLED Driver with Internal MOSFET

Universal Switch Mode

Electrical Specifications (Ta = 25^oC, V_DRAIN= 50V, unless otherwise noted)

Function Parameter

Internal Regulator

Symbol

Test Conditions

Min

Typ

Max Units

Internally Regulated Voltage

Drain Supply Voltage

Undervoltage Lockout Threshold

Undervoltage Lockout Hysteresis

Supply Current

V_DD

V_DRAIN

UVLO

∆UVLO

I_DD

7.5

4.0

200

µA

V_DD(EXT)=8.5V, V_DRAIN=40V

350

Output (Drain)

Breakdown Voltage

V_BR

R_DSON

C_DRAIN

I_SAT

475

210

5.0

Ω

On Resistance

I_DRAIN=50mA

V_DRAIN=400V

Output Capacitance

1.0

150

MOSFET Saturation current

Current Sense Comparator

Threshold Current

100

I_TH

200

300

Leading edge Blanking delay

Minimum Turn On-Time

Off-Time Generator

Turn On-Time

T_BLANK

T_ON(MIN)

400

650

T_OFF

10.5

µS

Note 1: The specification which apply over the full operating ambient temperature range of -40ºC<T_A<+85ºC

2: Guaranteed by design

Block Diagram

2/7

Version: B11

TS19451

AC/DC WLED Driver with Internal MOSFET

Universal Switch Mode

Function Description

The TS19451 is a PWM peak current controller for controlling a buck converter topology in continuous conduction

mode (CCM). The output current is internally preset at 50mA

When the input voltage of 20~400V appears at the Drain pin, the internal high-voltage linear regulator seeks to

maintain a voltage of 7.5VDC at the VDD pin. Until this voltage exceeds the internally programmed under-voltage

threshold, the output switching MOSFET is non-conductive. When the threshold is exceeded, the MOSFET turns

on. The input current begins to flow into the Drain pin. Hysteresis in provided in the under-voltage comparator to

prevent oscillation.

When the input current exceeds the internal preset level, a current sense comparator resets an RS flip-flop, and the

MOSFE turns off, At the same time, a one-shot circuit is activated that determines the duration of the off-state

(10.5µS typ.) As soon as this time is over, the flip-flop sets again. The new switching cycle begins.

A “blanking” delay of 300nS is provided that presents false triggering of the current sense comparator due to the

leading edge spike caused by circuit parasitic.

Application Information

The TS19451 is specifically designed for driving multi LED strings. It can be operated from either universal AC line

range of 85~264VAC or 20~400VDC, and drives up to tens of high brightness LEDs. All LEDs can be run in series

and this device regulates at constant current, yielding uniform illumination. It’s also compatible with triac dimmers.

Selecting L1 and D1

There is a certain trade-off to be considered between optimal sizing of the output inductor L1 and the tolerated

output current ripple. The required value of L1 is inversely proportional to the ripple current ∆I_Oin it.

L1 = (V_Ox T_OFF) / ∆I_O

V_Ois the forward voltage of the LED string. T_OFFis the off-time of the TS19451. The output current in the LED string

(I_O) is calculated as:

I_O= I_H– (∆I_O/ 2)

Where I_THis the current sense comparator threshold. The ripple current introduces a peak-to-average error in the

output current setting that needs to be accounted for. Due to constant off-time control technique used in the

TS19451, the ripple current is independent of the input AC or DC line voltage variation. Therefore, the output

current will remain unaffected by the varying input voltage.

According a filter capacitor across the LED string can reduce the output current ripple even further, thus permitting

a reduced value of L1. However, one must keep in mind that the peak-to-average current error is affected by the

variation of T_OFF. Therefore, the initial output current accuracy might be sacrificed at large ripple current in L1.

Another important aspect of designing an LED driver with TS19451 is related to certain parasitic elements of the

circuit, including distributed coil capacitance of L1, junction capacitance and reverse recover of the rectifier diode

D1, capacitance of the PCB traces C_PCBand output capacitance C_DRAINof the controller itself. These parasitic

elements affect the efficiency of the switching converter and could potentially cause false triggering of the current

sense comparator if not properly managed. Minimizing these parasitic is essential for efficient and reliable

operation of the TS19451.

Coil capacitance of inductors is typically provided in the manufacturer’s data books either directly or in terms of the

self-resonant frequency (SRF).

3/7

Version: B11

TS19451

AC/DC WLED Driver with Internal MOSFET

Universal Switch Mode

Application Information (Continue)

L is the inductance value, and C_Lis the coil capacitance. Charging and discharging this capacitance every

switching cycle causes high-current spikes in the LED string. Therefore, connecting a small capacitor C_O(~10nF) is

recommended to bypass these spikes.

Using an ultra-fast rectifier diode for D1 is recommended to achieve high efficiency and reduce the risk of false

triggering of the current sense comparator. Using diodes with shorter reverse recovery time t_rrand lower junction

capacitance C_Jachieves better performance. The reverse voltage rating V_Rof the diode must be greater than the

maximum input voltage of LED lamps.

The total parasitic capacitance present at the Drain pin of the TS19451 can be calculated as:

C_P= C_DRAIN+ C_PCB+ CL + C_J

When the switching MOSFET turns on, the capacitance C_Pis discharged into the Drain pin of the IC. The discharge

current is limited to about 150mA typically. However, it may become lower at increased junction temperature. The

duration of the leading edge current spike can be estimated as:

_PSIKE= ((V_INx C_P) / (I_SAT)) + t_r

In order to avoid false triggering of the current sense comparator, CP must be minimized in accordance with the

following expression:

Where T_BLANK(MIN)is the minimum blanking time of 200ns, and V_IN(MAX)is the maximum instantaneous input voltage.

EMI Filter

As with all off-line converters, selecting an input filter is critical to obtaining good EMI. A switching side capacitor,

albeit of small value, is necessary in order to ensure low impedance to the high frequency switching currents of the

converter. As a rule of thumb, this capacitor should be approximately 0.1~0.2µF/W of LED output power.

Typical Application Circuit for Universal 85~264VAC LED Lamps Driver

4/7

Version: B11

TS19451

AC/DC WLED Driver with Internal MOSFET

Universal Switch Mode

Electrical Characteristics Curve

Figure 2. Drain Breakdown Voltage vs. Output

Current

Figure 1. Threshold Current vs. Junction

Temperature

Figure 4. Drain Capacitance vs. Drain Voltage

Figure 3. OFF-Time vs. Junction Temperature

Figure 5. On-Resistance vs. Junction

Temperature

Figure 6. Drain Current vs. Drain Voltage

5/7

Version: B11

TS19451

AC/DC WLED Driver with Internal MOSFET

Universal Switch Mode

SOT-89 Mechanical Drawing

SOT-89 DIMENSION

MILLIMETERS

INCHES

MIN

DIM

MIN

4.40

1.50

2.30

0.40

1.50

3.00

0.89

4.05

1.4

MAX

4.60

1.7

MAX

0.181

0.070

0.102

0.020

0.059

0.118

0.047

0.167

0.068

0.017

0.173

0.059

0.090

0.016

0.059

0.118

0.035

0.159

0.055

0.014

2.60

0.52

1.50

3.00

1.20

4.25

1.6

0.35

0.44

Marking Diagram

= Year Code

= Month Code for Halogen Free Product

(O=Jan, P=Feb, Q=Mar, R=Apl, S=May, T=Jun, U=Jul, V=Aug, W=Sep,

X=Oct, Y=Nov, Z=Dec)

= Lot Code

6/7

Version: B11

TS19451

AC/DC WLED Driver with Internal MOSFET

Universal Switch Mode

Notice

Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf,

assumes no responsibility or liability for any errors or inaccuracies.

Information contained herein is intended to provide a product description only. No license, express or implied, to

any intellectual property rights is granted by this document. Except as provided in TSC’s terms and conditions of

sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty,

relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose,

merchantability, or infringement of any patent, copyright, or other intellectual property right.

The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.

Customers using or selling these products for use in such applications do so at their own risk and agree to fully

indemnify TSC for any damages resulting from such improper use or sale.

7/7

Version: B11

TS19451 [TSC]

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