IW1691-00 datasheet(7/24 Pages) DIALOG

Part #	IW1691-00

Description	Digital PWM Current-Mode Controller for Quasi-Resonant Operation

Download	24 Pages

Scroll/Zoom	100%

Manufacturer	DIALOG [Dialog Semiconductor]

Direct Link	http://www.dialog-semiconductor.com/

Logo

7 / 24 page

iW1691

Digital PWM Current-Mode Controller for Quasi-Resonant Operation

Rev. 2.0

iW1691

Page 7

FebRuaRy 3, 2012

9.1 Pin Detail

Pin 2 – V

SENSE

Sense signal input from auxiliary winding. This provides the

secondary voltage feedback used for output regulation.

Pin 3 – V

iN

Sense signal input from the rectified line voltage. V

IN is used

for line regulation. The input line voltage is scaled down

using a resistor network. It is used for input undervoltage

and overvoltage protection. This pin also provides the supply

current to the IC during start-up.

Pin 4 – SD

External shutdown control. If the shutdown control is not

used, this pin should be connected to GND via a resistor.

(see Section 10.16).

Pin 5 – GND

Ground.

Pin 6 – i

SENSE

Primary current sense. Used for cycle by cycle peak current

control.

Pin 7 – OUTPUT

Gate drive for the external MOSFET switch.

Pin 8 – V

CC

Power supply for the controller during normal operation. The

controller will start up when V

CC reaches 12 V (typical) and

will shut-down when the V

CC voltage is below 6 V (typical). A

decoupling capacitor should be connected between the V

CC

pin and GND.

9.2 Start-up

Prior to start-up the V

IN pin charges up the VCC capacitor

through the diode between V

IN and VCC (see Figure 8.1).

When V

CC is fully charged to a voltage higher than the start-

up threshold V

CC(ST), the ENABLE signal becomes active and

enables the control logic; the V

IN switch turns on, and the

analog-to-digital converter begins to sense the input voltage.

Once the voltage on the V

IN pin is above VINSTLOW , the iW1691

commences soft start function. An adaptive soft-start control

algorithm is applied at startup state, during which the initial

output pulses will be small and gradually get larger until the

full pulse width is achieved. The peak current is limited cycle

by cycle by Ipeak comparator.

If at any time the V

CC voltage drops below VCC(UVL) threshold

then all the digital logic is reset. At this time V

IN switch turns

off so that the V

CC capacitor can be charged up again towards

the start-up threshold.

VCC

VCC(ST)

ENABLE

Start-up

Sequencing

VIN

Figure 9.1 : Start-up Sequencing Diagram

9.3 Understanding Primary Feedback

Figure 9.2 illustrates a simplified flyback converter. When the

switch Q1 conducts during t

ON(t), the current ig(t) is directly

drawn from rectified sinusoid v

g(t). The energy Eg(t) is stored

in the magnetizing inductance L

M. The rectifying diode D1 is

reverse biased and the load current I

O is supplied by the

secondary capacitor C

O. When Q1 turns off, D1 conducts

and the stored energy E

g(t) is delivered to the output.

+

vin(t)

TS(t)

IO

VO

VAUX

N:1

D1

Q1

VAUX

CO

vg(t)

ig(t)

+

–

iin(t)

id(t)

Figure 9.2 : Simplified Flyback Converter

In order to tightly regulate the output voltage, the information

about the output voltage and load current needs to be

accurately sensed. In the DCM flyback converter, this

information can be read via the auxiliary winding. During the

Q

1 on-time, the load current is supplied from the output filter

capacitor C

O. The voltage across LM is vg(t), assuming the

voltage dropped across Q

1 is zero. The current in Q1 ramps

up linearly at a rate of:

()

g

M

di t

v t

dt

L

=

(9.1)

At the end of on-time, the current has ramped up to:

Similar Part No. - IW1691-00

Manufacturer	Part #	Datasheet	Description
Renesas Technology Corp	IW1691-00	2Mb / 32P	Digital PWM Current-Mode Controller for Quasi-Resonant Operation 22-Jan-2022

More results

Similar Description - IW1691-00

Manufacturer	Part #	Datasheet	Description
Renesas Technology Corp	IW1691	2Mb / 32P	Digital PWM Current-Mode Controller for Quasi-Resonant Operation 22-Jan-2022
Dialog Semiconductor	IW1710	1Mb / 20P	Digital PWM Current-Mode Controller for Quasi-Resonant Operation
Renesas Technology Corp	IW1710	1Mb / 30P	Digital PWM Current-Mode Controller for Quasi-Resonant Operation 24-Jan-2022
ON Semiconductor	NCP1338	221Kb / 15P	PWM Current-Mode Controller for Free Running Quasi-Resonant Operation March, 2010 ??Rev. 1
	NCP1338	160Kb / 15P	PWM Current-Mode Controller for Free Running Quasi-Resonant Operation March, 2010 ??Rev. 1
	NCP1207A	264Kb / 17P	PWM Current-Mode Controller for Free Running Quasi-Resonant Operation November, 2007 - Rev. 8
	NCP1207-D	202Kb / 18P	PWM Current-Mode Controller for Free Running Quasi-Resonant Operation June, 2004 ??Rev. 6
	NCP1377	251Kb / 17P	PWM Current-Mode Controller for Free-Running Quasi-Resonant Operation January, 2011 ??Rev. 11
	NCP1207A	401Kb / 17P	PWM Current--Mode Controller for Free Running Quasi--Resonant Operation December, 2010 -- Rev. 11
	NCP1377	251Kb / 17P	PWM Current-Mode Controller for Free-Running Quasi-Resonant Operation January, 2011 ??Rev. 11

More results

IW1691-00 Datasheet(PDF) 7 Page - Dialog Semiconductor

IW1691-00 Datasheet(HTML) 7 Page - Dialog Semiconductor

Similar Part No. - IW1691-00

Similar Description - IW1691-00

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

Datasheet Download

Link URL