TOP250 datasheet(20/54 Pages) POWERINT

20 / 54 page

Rev. R 10/20

TOP242-250

www.power.com

Figure 41. 30 W Power Supply using External Current Limit Programming and Line Sensing for UV and OV.

12 V @

2.5 A

1N4148

µF

10 V

LTV817A

VR2

1N5240C

10 V, 2%

150

Ω

R15

150

Ω

C14

1 nF

UF4005

68 k

Ω

2 W

4.7 nF

1 kV

CY1

2.2 nF

TOP244Y

150

Ω

µF

400 V

0.1

µF

MBR1060

C10

560

µF

35 V

C12

220

µF

35 V

C11

560

µF

35 V

RTN

6.8

Ω

4.7 M

Ω

1/2 W

2 M

Ω

1/2 W

9.09 k

Ω

PI-2657-081204

3.3

µH

BR1

600 V

3.15 A

20 mH

CX1

100 nF

250 VAC

CONTROL

TOPSwitch-GX

PERFORMANCE SUMMARY

Output Power:

30 W

Regulation:

± 4%

Efficiency:

≥ 79%

Ripple:

≤ 50 mV pk-pk

Application Examples

A High Efficiency, 30 W, Universal Input Power Supply

The circuit shown in Figure 41 takes advantage of several

of the TOPSwitch-GX features to reduce system cost and

power supply size and to improve efficiency. This design

delivers 30 W at 12 V, from an 85 VAC to 265 VAC input,

at an ambient of 50

°C, in an open frame configuration.

A nominal efficiency of 80% at full load is achieved using

TOP244Y.

The current limit is externally set by resistors R1 and R2

to a value just above the low line operating peak DRAIN

current of approximately 70% of the default current limit.

This allows use of a smaller transformer core size and/or

higher transformer primary inductance for a given output

power, reducing TOPSwitch-GX power dissipation, while

at the same time avoiding transformer core saturation

during start-up and output transient conditions. The

resistors R1 & R2 provide a signal that reduces the current

limit with increasing line voltage, which in turn limits the

maximum overload power at high input line voltage. This

function in combination with the built-in soft-start feature

of TOPSwitch-GX, allows the use of a low cost RCD clamp

(R3, C3 and D1) with a higher reflected voltage, by safely

limiting the TOPSwitch-GX drain voltage, with adequate

margin under worst case conditions. Resistor R4

provides line sensing, setting UV at 100 VDC and OV at

450 VDC. The extended maximum duty cycle feature of

TOPSwitch-GX (guaranteed minimum value of 75% vs.

64% for TOPSwitch-II) allows the use of a smaller input

capacitor (C1). The extended maximum duty cycle and

the higher reflected voltage possible with the RCD clamp

also permit the use of a higher primary to secondary

turns ratio for T1, which reduces the peak reverse voltage

experienced by the secondary rectifier D8. As a result

a 60 V Schottky rectifier can be used for up to 15 V

outputs, which greatly improves power supply efficiency.

The frequency reduction feature of the TOPSwitch-GX

eliminates the need for any dummy loading for regulation

at no load and reduces the no-load/standby consumption

of the power supply. Frequency jitter provides improved

margin for conducted EMI, meeting the CISPR 22 (FCC B)

specification.

Output regulation is achieved by using a simple Zener

sense circuit for low cost. The output voltage is determined

by the Zener diode (VR2) voltage and the voltage drops

across the optocoupler (U2) LED and resistor R6. Resistor

R8 provides bias current to Zener VR2 for typical regulation

of ±5% at the 12 V output level, over line and load and

component variations.

TOP250 数据表(PDF) 20 Page - Power Integrations, Inc.

TOP250 数据表(HTML) 20 Page - Power Integrations, Inc.

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 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

数据表下载

链接网址

TOP250 数据表(PDF) 20 Page - Power Integrations, Inc.

TOP250 数据表(HTML) 20 Page - Power Integrations, Inc.

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 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

数据表 下载

链接网址

数据表下载