ST HVLED805 User Manual

Off-line LED driver with primary-sensing

Features

■ 800 V, avalanche rugged internal power

MOSFET

■ 5% accuracy on constant LED output current

with primary control

■ Optocoupler not needed

■ Quasi-resonant (QR) zero voltage switching

(ZVS) operation

■ Internal HV start-up circuit

■ Open or short LED string management

■ Automatic self supply

■ Input voltage feed-forward for mains

independent cc regulation

HVLED805

SO16N

Table 1. Device summary

Order codes Package Packaging

HVLED805

SO16N

HVLED805TR Tape and reel

Tube

Applications

■ AC-DC led driver applications

■ LED retrofit lamps (i.e. E27, GU10)

Figure 1. Application diagram

VCC

PROTECTION &
FEEDFORWARD

LOGIC

DE MAG

Rdmg

DMG

Rfb

3.3V

LOG IC

Vref

CONSTANT

VOLT AGE

REGULATION

CONSTANT

CURRENT

REGULATION

Vc

COMP ILED GND SOURCE

Rcomp

Ccomp

CLED

DRIVING

LOGIC

HV start-u p &

SUPPLY LOGIC

Vref

1V

OCP

Vin

DRAIN

LED

...

Rsens e

October 2010 Doc ID 18077 Rev 1 1/29

www.st.com

29

Contents HVLED805

Contents

1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5.1 Power section and gate driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5.2 High voltage startup generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5.3 Secondary side demagnetization detection and triggering block . . . . . . . 15

5.4 Constant voltage operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

5.5 Constant current operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.6 Voltage feedforward block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.7 Burst-mode operation at no load or very light load . . . . . . . . . . . . . . . . . . 22

5.8 Soft-start and starter block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

5.9 Hiccup mode OCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

5.10 Layout recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

6 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2/29 Doc ID 18077 Rev 1

HVLED805 Description

1 Description

The HVLED805 is a high-voltage primary switcher intended for operating directly from the
rectified mains with minimum external parts to provide an efficient, compact and cost
effective solution for LED driving. It combines a high-performance low-voltage PWM
controller chip and an 800V, avalanche-rugged power MOSFET, in the same package.

The PWM is a current-mode controller IC specifically designed for ZVS (zero voltage
switching) fly-back LED drivers, with constant output current (CC) regulation using primary­sensing feedback. This eliminates the need for the opto-coupler, the secondary voltage
reference, as well as the current sense on the secondary side, still maintaining a good LED
current accuracy. Moreover it guarantees a safe operation when short circuit of one or more
LEDs occurs.

In addition, the device can also provide a constant output voltage regulation (CV): it makes
the application able to work safely when the LED string opens due to a failure.

Quasi-resonant operation is achieved by means of a transformer demagnetization sensing
input that triggers MOSFET’s turn-on. This input serves also as both output voltage monitor,
to perform CV regulation, and input voltage monitor, to achieve mains-independent CC
regulation (line voltage feed forward).

The maximum switching frequency is top-limited below 166 kHz, so that at medium-light
load a special function automatically lowers the operating frequency still maintaining the
operation as close to ZVS as possible. At very light load, the device enters a controlled
burst-mode operation that, along with the built-in high-voltage start-up circuit and the low
operating current of the device, helps minimize the residual input consumption.

Although an auxiliary winding is required in the transformer to correctly perform CV/CC
regulation, the chip is able to power itself directly from the rectified mains. This is useful
especially during CC regulation, where the fly-back voltage generated by the winding drops.

In addition to these functions that optimize power handling under different operating
conditions, the device offers protection features that considerably increase end-product’s
safety and reliability: auxiliary winding disconnection or brownout detection and shorted
secondary rectifier or transformer’s saturation detection. All of them are auto restart mode.

Doc ID 18077 Rev 1 3/29

Maximum ratings HVLED805

2 Maximum ratings

Table 2. Absolute maximum ratings

Symbol Pin Parameter Value Unit

V

I

V

T

1. Limited by maximum temperature allowed.

1,2, 13-16 Drain-to-source (ground) voltage -1 to 800 V

DS

1,2, 13-16 Drain current

I

D

1,2, 13-16 Single pulse avalanche energy (Tj = 25°C, ID = 0.7A) 50 mJ

E

av

V

cc

DMG

comp

P

tot

T

J

stg

3 Supply voltage (Icc < 25mA) Self limiting V

6 Zero current detector current ±2 mA

7 Analog input -0.3 to 3.6 V

Power dissipation @TA = 50°C 0.9 W

Junction temperature range -40 to 150 °C

Storage temperature -55 to 150 °C

(1)

1A

Table 3. Thermal data

Symbol Parameter Max. value Unit

R

R

Thermal resistance, junction-to-pin 10

thJP

Thermal resistance, junction-to-ambient 110

thJA

°C/W

4/29 Doc ID 18077 Rev 1

HVLED805 Electrical characteristics

3 Electrical characteristics

TJ = -25 to 125 °C, Vcc=14 V; unless otherwise specified.

Table 4. Electrical characteristics

Symbol Parameter Test condition Min. Typ. Max. Unit

Power section

V

(BR)DSS

I

DSS

Drain-source breakdown ID< 100 µA; Tj = 25 °C 800 V

V

= 750V; Tj = 125 °C

Off state drain current

DS

(See Figure 4 and note)

80 µA

Id=250 mA; Tj = 25 °C 11 14

R

DS(on)

C

Drain-source ON-state resistance

Effective (energy-related) output capacitance (See Figure 3)

oss

Id=250 mA; Tj = 125 °C 28

High-voltage start-up generator

V

Start

I

charge

V

CCrestart

Min. drain start voltage I

Vcc startup charge current

Vcc restart voltage
(Vcc falling)

< 100µA 40 50 60 V

charge

> V

> V

; Vcc<Vcc

Start

; Vcc<Vcc

Start

On,

On

45.57

+/-10%

9.5 10.5 11.5

V

DRAIN

Tj = 25 °C

V

DRAIN

(1)

After protection tripping 5

Supply voltage

Vcc Operating range After turn-on 11.5 23 V

Vcc

Vcc

Turn-on threshold

On

Turn-off threshold

Off

V

Zener voltage Icc = 20mA 23 25 27 V

Z

(1)

(1)

12 13 14 V

91011V

Supply current

Ω

mA

V

Icc

start-up

Start-up current (See Figure 5) 200 300 µA

Iq Quiescent current (See Figure 6)11.4mA

Icc Operating supply current @ 50 kHz (See Figure 7)1.41.7mA

Iq

(fault)

Fault quiescent current

During hiccup and brownout
(See Figure 8)

250 350 µA

Start-up timer

T

RESTART

T

START

Start timer period 105 140 175 µs

Restart timer period during burst mode 420 500 700 µs

Demagnetization detector

I

DMGb

Input bias current V

= 0.1 to 3V 0.1 1 µA

DMG

Doc ID 18077 Rev 1 5/29

Electrical characteristics HVLED805

Table 4. Electrical characteristics (continued)

Symbol Parameter Test condition Min. Typ. Max. Unit

V

DMGH

V

DMGL

V

DMGA

V

DMGT

I

DMGON

T

BLANK

Upper clamp voltage I

Lower clamp voltage I

= 1 mA 3.0 3.3 3.6 V

DMG

= - 1 mA -90 -60 -30 mV

DMG

Arming voltage positive-going edge 100 110 120 mV

Triggering voltage negative-going edge 50 60 70 mV

Min. source current during MOSFET ON-time -25 -50 -75 µA

V

≥ 1.3V 6

Trigger blanking time after MOSFET’s turn-off

COMP

= 0.9V 30

V

COMP

Line feedforward

R

Equivalent feedforward resistor I

FF

= 1mA 45 Ω

DMG

Transconductance error amplifier

(1)

= ±10 µA

= 1.65 V

(1)

2.45 2.51 2.57

2.4 2.6

1.3 2.2 3.2 mS

V

REF

Voltage reference

gm Transconductance

Tj = 25 °C

Tj = -25 to 125°C and
Vcc=12V to 23V

ΔI

COMP

V

COMP

Gv Voltage gain Open loop 73 dB

GB Gain-bandwidth product 500 kHz

I

COMP

V

COMPH

V

COMPL

V

COMPBM

Source current V

Sink current V

Upper COMP voltage V

Lower COMP voltage V

Burst-mode threshold 1 V

= 2.3V, V

DMG

= 2.7V, V

DMG

= 2.3V 2.7 V

DMG

= 2.7V 0.7 V

DMG

= 1.65V 70 100 µA

COMP

= 1.65V 400 750 µA

COMP

Hys Burst-mode hysteresis 65 mV

µs

V

Current reference

V

V

ILEDx

CLED

Maximum value

V

COMP

= V

Current reference voltage 0.192 0.2 0.208 V

COMPL

(1)

1.5 1.6 1.7 V

Current sense

t

LEB

d(H-L) Delay-to-output 300 ns

t

V

V

CSdis

1. Parameters tracking each other

Leading-edge blanking 200 250 300 ns

Max. clamp value

CSx

Hiccup-mode OCP level

(1)

dVcs/dt = 200 mV/µs 0.7 0.75 0.8 V

(1)

0.92 1 1.08 V

6/29 Doc ID 18077 Rev 1

HVLED805 Pin connection

4 Pin connection

Figure 2. Pin connection (top view)

SOURCE

SOURCE

VCC

GND

ILED

DMG

COMP

N.A. N.A.

2

3

4

5

6

7

8

16

15

14

13

12

11

10

DRAIN1

DRAIN

DRAIN

DRAIN

N.C.

N.A.

N.A.

9

Note: The copper area for heat dissipation has to be designed under the drain pins

Doc ID 18077 Rev 1 7/29

Pin connection HVLED805

Table 5. Pin functions

N. Name Function

Power section source and input to the PWM comparator. The current flowing in the MOSFET
is sensed through a resistor connected between the pin and GND. The resulting voltage is

1, 2 SOURCE

3VCC

4GND

5ILED

6DMG

7COMP

8-11 N.A Not available. These pins must be left not connected

12 N.C Not internally connected. Provision for clearance on the PCB to meet safety requirements.

compared with an internal reference (0.75V typ.) to determine MOSFET’s turn-off. The pin is
equipped with 250 ns blanking time after the gate-drive output goes high for improved noise
immunity. If a second comparison level located at 1V is exceeded the IC is stopped and
restarted after Vcc has dropped below 5V.

Supply Voltage of the device. An electrolytic capacitor, connected between this pin and
ground, is initially charged by the internal high-voltage start-up generator; when the device is
running the same generator will keep it charged in case the voltage supplied by the auxiliary
winding is not sufficient. This feature is disabled in case a protection is tripped. Sometimes a
small bypass capacitor (100nF typ.) to GND might be useful to get a clean bias voltage for the
signal part of the IC.

Ground. Current return for both the signal part of the IC and the gate drive. All of the ground
connections of the bias components should be tied to a trace going to this pin and kept
separate from any pulsed current return.

CC regulation loop reference voltage. An external capacitor will be connected between this
pin and GND. An internal circuit develops a voltage on this capacitor that is used as the
reference for the MOSFET’s peak drain current during CC regulation. The voltage is
automatically adjusted to keep the average output current constant.

Transformer’s demagnetization sensing for quasi-resonant operation. Input/output voltage
monitor. A negative-going edge triggers MOSFET’s turn-on. The current sourced by the pin
during MOSFET’s ON-time is monitored to get an image of the input voltage to the converter,
in order to compensate the internal delay of the current sensing circuit and achieve a CC
regulation independent of the mains voltage. If this current does not exceed 50µA, either a
floating pin or an abnormally low input voltage is assumed, the device is stopped and
restarted after Vcc has dropped below 5V. Still, the pin voltage is sampled-and-held right at
the end of transformer’s demagnetization to get an accurate image of the output voltage to be
fed to the inverting input of the internal, transconductance-type, error amplifier, whose non­inverting input is referenced to 2.5V. Please note that the maximum I
current has to not exceed ±2 mA (AMR) in all the Vin range conditions. No capacitor is
allowed between the pin and the auxiliary transformer.

Output of the internal transconductance error amplifier. The compensation network will be
placed between this pin and GND to achieve stability and good dynamic performance of the
voltage control loop.

sunk/sourced

DMG

Drain connection of the internal power section. The internal high-voltage start-up generator

13 to 16 DRAIN

8/29 Doc ID 18077 Rev 1

sinks current from this pin as well. Pins connected to the internal metal frame to facilitate heat
dissipation.

HVLED805 Pin connection

Figure 3. C

output capacitance variation

OSS

C

(pF)

OSS

500

400

300

200

100

0

0 25 50 75 100 125 150

(V)

V

DS

Figure 4. Off state drain and source current test circuit

DMG

Note: The measured I

µA typ. @ 750 V) and the effective MOSFET’s off state drain current

+

14V

-

VCC DRAIN

2.5V

is the sum between the current across the 12 MΩ start-up resistor (62.5

DSS

CUR RE NT
CONTROL

GND

S OUR CEIL EDCOM P

Idss

A

+

Vin

­75 0V

Doc ID 18077 Rev 1 9/29