L6561D013TR 参数 Datasheet PDF下载

L6561

Table 5. Electrical Characteristics

(continued)

(V

CC

= 14.5V; T

amb

= -25°C to 125°C;unless otherwise specified)

Symbol

V

ZCD

I

ZCD

I

ZCD

I

ZCD

V

DIS

I

ZCD

V

GD

Pin

5

5

5

5

5

5

7

Parameter

Lower Clamp Voltage

Sink Bias Current

Source Current Capability

Sink Current Capability

Disable threshold

Restart Current After Disable

Dropout Voltage

V

ZCD

< V

dis

; V

CC

> V

CCOFF

I

GDsource

= 200mA

I

GDsource

= 20mA

I

GDsink

= 200mA

I

GDsink

= 20mA

t

r

t

f

I

GD off

I

OVP

7

7

7

2

Output Voltage Rise Time

Output Voltage Fall Time

IGD Sink Current

OVP Triggering Current

Static OVP Threshold

RESTART TIMER

t

START

Start Timer

70

150

400

µs

C

L

= 1nF

C

L

= 1nF

V

CC

=3.5V V

GD

= 1V

5

35

2.1

40

40

10

40

2.25

Test Condition

I

ZCD

= -3mA

1V

≤

V

ZCD

≤

4.5V

-3

3

150

-100

200

-200

1.2

0.7

Min.

0.3

Typ.

0.65

2

-10

10

250

-300

2

1

1.5

0.3

100

100

-

45

2.4

Max.

1

Unit

V

µA

mA

mA

mV

µA

V

V

V

V

ns

ns

mA

µA

V

OUTPUT SECTION

OUTPUT OVERVOLTAGE SECTION

3

OVER VOLTAGE PROTECTION OVP

The output voltage is expected to be kept by the operation of the PFC circuit close to its nominal value.

This is set by the ratio of the two external resistors R1 and R2 (see fig. 5), taking into consideration that

the non inverting input of the error amplifier is biased inside the L6561 at 2.5V.

In steady state conditions, the current through R1 and R2 is:

V

out

–

2.5

2.5V

-

I

R1sc

= ------------------------- =

I

R2

= ------------

R1

R2

and, if the external compensation network is made only with a capacitor C

comp

, the current through C

comp

equals zero.When the output voltage increases abruptly the current through R1 becomes:

V

outsc

+

∆

V

out

–

2.5

I

R1

= ---------------------------------------------------- =

I

R1sc

+

∆

I

R1

-

R1

Since the current through R2 does not change,

∆I

R1

must flow through the capacitor C

comp

and enter the

error amplifier.

This current is monitored inside the L6561 and when reaches about 37µA the output voltage of the multi-

plier is forced to decrease, thus reducing the energy drawn from the mains. If the current exceeds 40µA,

the OVP protection is triggered (Dynamic OVP), and the external power transistor is switched off until the

current falls approximately below 10µA.

However, if the overvoltage persists, an internal comparator (Static OVP) confirms the OVP condition

keeping the external power switch turned off (see fig. 4).Finally, the overvoltage that triggers the OVP

function is:

∆V

out

= R

1

· 40µA.

Typical values for R

1

, R

2

and C are shown in the application circuits. The overvoltage can be set indepen-

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