Datenblatt-pdf.com


EM8822A Schematic ( PDF Datasheet ) - Excelliance MOS

Teilenummer EM8822A
Beschreibung Single stage Buck/Buck-Boost PFC Controller
Hersteller Excelliance MOS
Logo Excelliance MOS Logo 




Gesamt 9 Seiten
EM8822A Datasheet, Funktion
EM8822A
Single stage Buck/Buck-Boost PFC Controller for LED Lighting
Applications
General Description
EM8822A is a voltage mode Buck/Buck-boost PFC
controller operating at transition mode. It keeps
the Buck / Buck-boost converter in constant on
time operation to achieve high power factor.
This device provides protections of internal soft
start, over voltage protection, over current
protection and thermal shutdown. It can minimize
the external components counts, and makes the
design easy.
This part is available in SOP-23-6 package.
Applications
General LED lighting applications
Bulb lamp
Tube lamp
PAR lamp
Pin Configuration
Ordering Information
Part Number Package
EM8822AJ SOP-23-6
Remark
EM8822A
Features
Single stage Buck/Buck-Boost PFC controller
Voltage Mode Control
Valley turn on of the MOSFET to achieve
lower switching loss
Low Start Up Current : 6uA typical
Maximum gate drive voltage at 19.5V
Over Voltage Protection for IC bias voltage
LED Open/Short Protection
Internal over-thermal Shutdown
2014/03/21
preliminary
1






EM8822A Datasheet, Funktion
EM8822A
Functional Description
EM8822A is a constant current Buck/Buck-Boost
PFC controller targeting at LED lighting applications.
The device is designed to operate in transition
mode (TrM) and is suitable for single stage Buck PFC
as well as Buck-Boost PFC converters in constant on
time operation to achieve high power factor.
EM8822A provides reliable protections such as LED
Short Circuit Protection, LED Open Protection, Over
Temperature Protection (OTP)..
Start up
After AC source or DC BUS is powered on, the
capacitor CVDD across VDD and GND pin is charged up
by VBUS voltage through a start up resistor RST. The
start-up current of IC is 6uA typical. Once VDD rises
up to UVLO(on), the internal blocks start to work.
VDD will be pulled down by operation current of IC
until the bias supply circuit could supply enough
energy to maintain VDD above UVLO(off).
The whole start-up procedure is divided to two
figures shown in Fig.14 and Fig.15. tSTC is the CVDD
charged up section, and tSTO is the output voltage
built-up section. The start-up time tST composes of
tSTC and tSTO, and usually tSTO is smaller than tSTC.
Select the CVDD to get an ideal start up time tST and
ensure the output voltage is built up without
another startup.
CVDD
=
(
VBUS
R ST
-IST )
UVLO(on)
(1)
,
IST start up current.
Fig. 15
Zero current detect
The zero current detect (ZCD) generates the turn-on
signal of the MOSFET when the inductor current
reaches zero current using an auxiliary winding
voltage or output voltage that’s coupled with the
inductor.
If the voltage of the ZCD pin goes higher than 1.4V
that its action is ready to aim, the ZCD comparator
waits until the voltage goes below 0.7V. And when
the voltage goes below 0.7V, the internal logic turns
on the MOSFET. That is shown in Fig.3.
The ZCD pin is protected internally by two clamps,
6.7V high voltage clamp and 0.3V low voltage clamp.
VZCD
aim(1.4V)
trig(0.7V)
VGATE
EM8822A
Fig. 14
on off
on
delay time (250ns) t
Fig. 15
2014/03/21
preliminary
6

6 Page







SeitenGesamt 9 Seiten
PDF Download[ EM8822A Schematic.PDF ]

Link teilen




Besondere Datenblatt

TeilenummerBeschreibungHersteller
EM8822ASingle stage Buck/Buck-Boost PFC ControllerExcelliance MOS
Excelliance MOS

TeilenummerBeschreibungHersteller
CD40175BC

Hex D-Type Flip-Flop / Quad D-Type Flip-Flop.

Fairchild Semiconductor
Fairchild Semiconductor
KTD1146

EPITAXIAL PLANAR NPN TRANSISTOR.

KEC
KEC


www.Datenblatt-PDF.com       |      2020       |      Kontakt     |      Suche