Instrukcja obsługi Microchip HV9925DB1

Microchip nieskategoryzowany HV9925DB1

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Supertex inc.

www.supertex.com

Doc.# DSDB-HV9925DB1

A032913

HV9925DB1

Introduction

The Supertex HV9925DB1 demo board is a complete LED

power driver to supply a string of LEDs using the HV9925,

an integrated, high-voltage, buck regulator IC featuring

programmable output current and PWM dimming. The

HV9925 includes a 500V switching MOSFET and can operate

directly from rectied AC line voltages of 80 to 135VAC.

The current in the LED string is externally programmed

to 50mA ±10% by a single resistor RS. The HV9925DB1

is ideally suited for driving strings of LEDs having forward

voltage from 20V to 60V at high efciency.

The HV9925DB1 is a peak current-controlled buck converter

operating with a xed off-time of 10.5µs. Its’ xed off-time

control scheme provides good stability and tight regulation of

the LED current throughout the input AC line voltage range.

As its switching frequency varies over the AC line cycle, the

HV9925 inherently introduces frequency dither and simplies

the compliance with EMI regulations.

Specications

Board Layout and Connection Diagram

Programmable-Current 120VAC

LED Driver Demoboard

with PWM Dimming

Parameter Value

Input voltage range 80 to 135VAC

Load current 50mA ± 10%

LED string voltage 20~60V

Conducted EMI CISPR15

Efciency 82% typ.

Actual Size: 40mm x 23mm x 16mm AC Line

80 - 135VAC

PWM

Dimming

Connections

LED+: Connect the Anode of the LED string to this pin.

LED-: Connect the Cathode of the LED string to this pin.

AC1, AC2: Connect AC Line to these pins.

Note:

The demoboard is not protected from output open/short

circuit condition. Damage to the demoboard may occur if

the output load is not properly connected

Supertex inc.

www.supertex.com

Doc.# DSDB-HV9925DB1

A032913

HV9925DB1

Schematic Diagram

Testing the HV9925DB1

Connect the LED string to the output terminals.

Check the polarity of the LED connection. The anode end

of the string should be connected to the positive output, and

the cathode should be connected to the negative output.

Connect the AC input to the input terminals. Apply the AC

voltage at the input terminals and the LED string should

start to glow. The HV9925DB1 will regulate constant 50mA

current in the LED. An ammeter can be connected in series

with the LED(s) to measure the output current.

PWM Dimming HV9925DB1

Remove the jumper J1 and connect to an output of the

square-wave signal generator using an opto-isolator.

Note:

The HV9925DB1 circuit is not isolated from AC mains.

Connecting external devices to J1 without using opto-

isolators can be hazardous and may cause equipment

damage.

+DF06M

AC1

AC2

2R1

100, 1/4W 1

3.3µF

250V A

LED+

OUT

.01uF

1 2

22mH

LED-

1 2

8.2

PWMD

0.1uF

VDD

GND

RSENSE

GND

PWMD

N/C

VDD

DRAIN

HV9925

US1G

Typical Performance Characteristics

Fig. 1 pical Efficiency at VTy

OUT

= 50V Fig. 2 AC Line Regulation of LED Current at V

OUT

= 50V

72.00

74.00

76.00

78.00

80.00

82.00

84.00

80 90 100 0 120 130 14011

Input AC Voltage, CVA

Efficiency, %

47.4

47.6

47.8

48.0

48.2

48.4

48.6

48.8

49.0

80 90 100 0 120 130 14011

Input AC Voltage, CVA

LED Current, mA

Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives

an adequate “product liability indemnification insurance agreement.” does not assume responsibility for use of devices described, and limits its liabilit Supertex inc. y

to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and