1 LCDTV AC/DC Power range Input Power 14” LCD TV 44 W 70W 140W 180W 195W 285W 20” LCD TV 26” LCD TV 32” LCD TV 37” LCD TV 40” LCD TV Wide Input voltage range: 90-265VAC Multi Output Voltages (Vout): Vout Current Remarks 24V 12V 5V 5VSTB 8A 3A 2A 1A ML4800/FAN4800(PFC+PWM) + FAN7382(AHB driver) FSCQ0765 with Sync rectification FAN5234 FSDM311 Total output Power : 243W 300W input LCD-TV SMPS Specifications
41
Embed
1 LCDTV AC/DC Power range Input Power 14” LCD TV 44 W 70W 140W 180W 195W 285W 20” LCD TV 26” LCD TV 32” LCD TV 37” LCD TV 40” LCD TV Wide Input voltage.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
LCDTV AC/DC Power range
Input Power
14” LCD TV
44 W 70W 140W 180W 195W 285W
20” LCDTV
26” LCD TV
32” LCD TV
37” LCD TV
40” LCDTV
Wide Input voltage range: 90-265VAC
Multi Output Voltages (Vout):
Vout Current Remarks
24V
12V
5V
5VSTB
8A
3A
2A
1A
ML4800/FAN4800(PFC+PWM) + FAN7382(AHB driver)
FSCQ0765 with Sync rectification
FAN5234
FSDM311
Total output Power : 243W
300W input LCD-TV SMPS Specifications
2
AHB TOPOLOGY• Asymmetric control half bridge converter
ML4800/FAN4800 A High Performance PFCAverage Current,CCM
ML4800/ML4824
10
ML4800/FAN4800 A More Detail Circuit…
11
An Example: ML4800
12
ML4800/FAN4800 Gain Modulator---(I)
• Gain Modulator:
Generate the reference current wave-form.
IAC Input: rectified AC input sine wave
Decides the “Shape” of the current Reference
VEAO Input: Vo
Decides the “Size” of the current Reference
to regulate the Vo.
VRMS Input: RMS AC line voltage
Feed-forward the 1 / Vin(rms)2 to speed up the
response & maintain a constant loop gain.
13
ML4800/FAN4800 Gain Modulator---(II)
ACIn
V O U TL1 D 2
R SEN SE
–
+
Error Am p
P W M
C LO C K
Vin
Isense
IGainmod
Vin↑2Vin, then Isense↑2Isense,=>Pin↑4Pin => Vout ↑↑. So it is necessary for a RMS AC line voltage feed forward to make Isense ↓0.5Isense while Vin↑2Vin.
14
ML4800/FAN4800 Gain Modulator---(III)
K is a function of VRMS-2 . Left is the K/ VRMS curve
* the K of the curve is in units of m V-1
•IGAINMOD = GAIN * IAC
= K * (VEAO- 0.625 ) * IAC , K is in units of V-1
Average line voltage compensation with brownout control
15
ML4800/FAN4800 Gain Modulator---(IV)• Continuous mode PFC controllers
modify the gain error in the control loop
• For voltages in the range 85V to 220V, the gain curve compensates for the Vrms dependency
• Without this compensation, the gain of the control loop would be directly proportional to Vrms2
• For voltages below 85V, the gain curve provides brownout protection
Modulator compensates for effect of loop gain increase with VIN(RMS)
2 with piecewise linear curve
16
ML4800/FAN4800:“Slew Enhanced” Error Amp Improves
Transient Response
V O U T
Vre
f
T oM ultip lier
VFB
•Special shaped, non-linear gain error amplifiers are used.
Such that under steady-state operating conditions the transconductance of the error amplifier is at a local minimum.
Lower gain to get higher PF when in Steady State.
Higher gain to get fast transient response
17
ML4800/FAN4800 VFB (Pin 15) Tri-Fault Detect
• Should VFB go too low (* Pin 15 < 0.5 V ), too high (* Pin 15 > 2.75 V), or open, the internal Tri-Fault Detect circuit will senses the error and terminates the PFC output driver.
18
ML4800/FAN4800 Switching Frequency Setting(Pin7)
ML4824-1:fpwm=fpfc
ML4824-2: fpwm=2fpfc
ML4800:fpwm=fpfc
fpfc ≈ 1/ (0.51* RT CT )
IAC
Isens
Vrms
SS
VDC
RAMP1
RAMP2
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
IEAO VDC
VFB
VREF
Vcc
PFC OUT
PWM OUT
GND
DCI LMIT
IAC
Isense
VRMS
SS
VDC
RAMP1
RAMP2
R38 (*=RT)
C18 (*=CT)
19
ML4800/FAN4800 Vin OK Comparator
• The Vin OK Comparator monitors the DC output of the PFC and inhibit the PWM if the voltage on the VFB is less than 2.45 V. Once this voltage reaches over 2.45 V, the soft-start of the PWM section begins.
20
ML4800/FAN4800 PWM Soft Start (Pin 5) --- (I)
• Chose
Css = tDELAY * (25 uA/1.25V)
Where Css is the soft start Cap.
tDELAY is the desired Start-
up delay.
During the tDELAY only the PFC works. PWM does not work. After then, the duty of the PWM O/P begins to (gradually) expand to its normal condition.
•the DC ILIMIT input is used for output stage overcurrent protection.
25
ML4800/FAN4800 PFC/PWM Combo Controllers
• Combine: Leading edge PFC and trailing edge PWM in one package
PFC turn off, then PWM turn on, at the same instant to minimize
the momentary “no-load” period, thus lowering ripple voltage generated by the switching action.
PFC switch
PWM switch
26
Project
(Part #)Family Description Application Package
Current
Code D ER sample Code R Code S
FAN4800 PFC IC Same die with CM6800 PC, Server16DIP
16SOP- 2005-04-27 2005-05-18 2005-06-15
Block Diagram Description
Features
The FAN4800 is a controllers for power factor corrected, switched mode power supplies. PowerFactor Correction (PFC) enables the use of smaller, lower cost bulk storage capacitors, reduces power line loading, and reduces stress on the components of a switched mode power supply.
Average Current Mode 23V BiCMOS Process Vcc OVP, Brown out, UVLO, Soft start Low Power Detect Comparator More Precise Spec. for OVP, OCP, Tri-Fault Low Power Consumption : 100uA, 3mA 16-pin Solution
• Features– - Optimized for Quasi-resonant converter (Low EMI and High Efficiency)– - Fully avalanche rated and 100% tested SenseFET– - Pulse-by-pulse current limiting– - Improved reliability through various protection functions
• : Over voltage, Over load, Over current, Thermal shutdown– - Advanced Burst operation for low power consumption in standby (<1W)- - Internal Soft start function (20ms)- - Extended Quasi-resonant operation for wide operation range- - Reduced startup and operating currents
• Advantages– - Reduced board space (simple & compact circuit design)– - Decreased assembly time and field failure rate Enhanced productivity