NCP1271 datasheet(16/19 Pages) ONSEMI

Part #	NCP1271

Description	Soft?뭆kip Mode Standby PWM Controller with Adjustable Skip Level and External Latch

Download	19 Pages

Scroll/Zoom	100%

Manufacturer	ONSEMI [ON Semiconductor]

Direct Link	http://www.onsemi.com

Logo

16 / 19 page

NCP1271

http://onsemi.com

16

Recover from Standby

In the event that a large load is encountered during skip

cycle operation, the circuit automatically disables the

normal Soft−Skip procedure and delivers maximum power

to the load (Figure 37). This feature, the Transient Load

Detector (TLD), is initiated anytime a skip event is exited

and the FB pin is greater than 2.85 V, as would be the case

for a sudden increase in output load.

Figure 37. Transient Response from Standby

V

VFB

ID

skip

VTLD

load current

Maximum current available

when TLD level is hit

output voltage

300 ms max

External Latchoff Shutdown

When the Skip/Latch input (Pin 1) is pulled higher than

Vlatch (8.0 V typical), the drive output is latched off until

VCC drops below VCC(reset) (4.0 Vtypical). If Vbulk stays

above approximately 30 Vdc, then the HV FET ensure that

VCC remains above VCC(latch) (5.8 Vtypical). Therefore, the

controller is reset by unplugging the power supply from the

wall and allowing Vbulk to discharge. Figure 38 illustrates

the timing diagram of VCC in the latchoff condition.

Figure 38. Latchoff VCC Timing Diagram

5.8 V

12.6 V

Startup current source is

charging the VCC capacitor

Startup current source is

off when VCC is 12.6 V

Startup current source turns

on when VCC reaches 5.8 VCC

Figure 39 defines the different voltage regions of the

Skip/latch Pin (Pin 1) operation.

1. When the voltage is above Vlatch (7.1 V min,

8.7 V max), the circuit is in latchoff and all drive

pulses are disabled until VCC cycles below 4.0 V

(typical).

2. When the voltage is between Vskip−reset (5.0 V

min, 6.5 V max) and Vlatch, the pin is considered

to be opened. The skip level Vskip is restored to

the default 1.2 V.

3. When the voltage is between about 3.0 V and

Vskip−reset, the Vskip level is above the normal

operating range of the feedback pin. Therefore,

the output does not switch.

4. When the voltage is between 0 V and 3.0 V, the

Vskip is within the operating range of the

feedback pin. Then the voltage on this pin sets

the skip level as explained earlier.

Figure 39. NCP1271 Pin 1 Operating Regions

Output is latched off here.

Adjustable V

range.

0 V (no skip)

3.0 V (always skip)

V pin1

8V (V

)

10 V (max limit)

Output always low (skipped) here.

5.7 V (V

)

Pin 1 considered to be opened.

skip−reset

latch

skip

Vskip is reset to default level 1.2 V.

The external latch feature allows the circuit designers to

implement different kinds of latching protection. The

NCP1271 applications note (AND8242/D) details several

simple circuits to implement overtemperature protection

(OTP) and overvoltage protection (OVP).

In order to prevent unexpected latchoff due to noise,

it is very important to put a noise decoupling capacitor

near Pin 1 to increase the noise immunity. It is also

recommended to always have a resistor from pin 1 to GND.

This further reduces the risk of premature latchoff. Also

note that if the additional latch−off circuitry has leakage,

it will modify the skip adjust setup.

External Non−Latched Shutdown

Figure 40 illustrates the Feedback (pin 2) operation. An

external non−latched shutdown can be easily implemented

by simply pulling FB below the skip level. This is an

inherent feature from the standby skip operation. Hence, it

allows the designer to implement additional non−latched

shutdown protection.

The device can also be shutdown by pulling the VCC pin

to GND (<190 mV). In addition to shutting off the output,

this method also places the part into a low current

consumption state.

Similar Part No. - NCP1271

Manufacturer	Part #	Datasheet	Description
ON Semiconductor	NCP1271	739Kb / 6P	Power Factor Controllers Rev. 7, Sep-2006
	NCP1271	239Kb / 21P	Soft-Skip Mode Standby PWM Controller with Adjustable Skip Level and External Latch September, 2009 ??Rev. 6
	NCP12711	1Mb / 24P	Current Mode PWM Controller April, 2022 - Rev. P0
	NCP12711ADNR2G	1Mb / 24P	Current Mode PWM Controller April, 2022 - Rev. P0
	NCP1271P100G	239Kb / 21P	Soft-Skip Mode Standby PWM Controller with Adjustable Skip Level and External Latch September, 2009 ??Rev. 6

More results

Similar Description - NCP1271

Manufacturer	Part #	Datasheet	Description
ON Semiconductor	NCP1271P100G	239Kb / 21P	Soft-Skip Mode Standby PWM Controller with Adjustable Skip Level and External Latch September, 2009 ??Rev. 6
	NCP1271	239Kb / 21P	Soft-Skip Mode Standby PWM Controller with Adjustable Skip Level and External Latch September, 2009 ??Rev. 6
	NCP1219	207Kb / 20P	PWM Controller with Adjustable Skip Level and External Latch Input May, 2009 ??Rev. 1
	NCP1218	209Kb / 20P	PWM Controller with Adjustable Skip Level and External Latch Input October, 2009 ??Rev. 1
	NCP1219BD100R2G	185Kb / 20P	PWM Controller with Adjustable Skip Level and External Latch Input October, 2009 ??Rev. 3
	NCP1219	178Kb / 20P	PWM Controller with Adjustable Skip Level and External Latch Input February, 2022 - Rev. 4
	NCP1230A	2Mb / 21P	Low--Standby Power Soft Skip Mode Controller December, 2010 -- Rev. 7
Maxim Integrated Produc...	MAX16952EVKIT	829Kb / 8P	Selectable Forced Fixed-Frequency PWM Mode, SKIP Mode, or External Synchronization Rev 1; 1/12
Grenergy Opto, lnc.	GR8837	721Kb / 14P	Green-Mode PWM Controller with Latch Protection
Excelliance MOS Corp.	EM8633	258Kb / 12P	Green mode PWM Flyback Controller with External Over

More results

NCP1271 Datasheet(PDF) 16 Page - ON Semiconductor

NCP1271 Datasheet(HTML) 16 Page - ON Semiconductor

Similar Part No. - NCP1271

Similar Description - NCP1271

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Datasheet Download

Link URL