LX1562IDM Microsemi Analog Mixed Signal Group, LX1562IDM Datasheet - Page 20

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LX1562IDM

Manufacturer Part Number
LX1562IDM
Description
IC CONTROLLER PFC 13.1V 8SOIC
Manufacturer
Microsemi Analog Mixed Signal Group
Datasheet

Specifications of LX1562IDM

Mode
Discontinuous Conduction (DCM)
Frequency - Switching
1.7MHz
Current - Startup
200µA
Voltage - Supply
11 V ~ 25 V
Operating Temperature
0°C ~ 100°C
Mounting Type
Surface Mount
Package / Case
8-SOIC
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
LX1562/1563
20
ERROR AMPLIFIER COMPONENT SELECTION
Capacitor C5 is primarily selected to reject the output ripple
associated with twice the line frequency. For a 40dB ripple
rejection:
Resistor R9 can be used to improve load transient response at the
cost of loosing 1 or 2% of load regulation. The value of this resistor
should be much greater than R8:
One way of achieving desired load transient response without
resorting to a complex mathematical model of the converter, is to
dynamically switch the output load and empirically find the
compensation network. The value of resistor R9 is selected using
the method shown in Figure 34.
I
Figure 35 shows voltage envelope generated by flyback voltage
across I
and R4 resistor:
DETECT
Select turns ratio n such that,
n =
n =
I
selected to be 7T.
Select R4 = 22k
DET
C5
C5
R9 = 620k
0.11 * 230
n * V
3 * 10
3 * 10
COMPONENT SELECTION
winding turns are
V
230 - 2 * 130
DET
FIGURE 34 — LOAD TRANSIENT RESPONSE CIRCUIT
BOOST
BOOST
2
2
winding:
-3
-3
100
5V
* 120 * 2.2 * 10
f
l
- 2 V
R7
5V
< R4 < 500k
< R4 < 500k, or
100
V
BOOST
AC (MAX)
= 0.11
6
Min.
Load
where f
= 0.062µF,
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
S
FIGURE 35 — FLYBACK VOLTAGE
E C O N D
R
L
8.4k < R4 < 500k
l
= 2x line frequency
ACROSS I
P
A P P L I C A T I O N I N F O R M A T I O N
-G
R O D U C T I O N
Select C5 = 0.1µF
50% D.C.
10Hz
n (V
(continued)
E N E R AT I O N
DET
BOOST
WINDING
- V
AC
)
nV
P
AC
O W E R
D
SUPPLY VOLTAGE
Resistor R3 must be selected such that it ensures converter start-
up at low line and is rated for high line power dissipation.
Start-up time of converter is given by:
The start-up capacitor is selected such that capacitor discharge
time is always longer than the time it takes for the bootstrap
voltage to reach above the minimum start-up threshold of the IC.
Start-up time is approximately 0.8 seconds.
The auxiliary winding turns are selected such that it provides 15V
of operating voltage.
However, in this example I
which eliminates the need for a third winding. This is possible
since the internal clamping of the output drive limits the gate
drive voltage to 14V (typ.) if the supply voltage exceeds this limit.
A T A
F
R3 <
R3 <
R3 > 4 V
R3 > 68k ,
T
for our application this will be 25ms/µF.
C3 <
C3 <
Select C3 = 33µF.
N
A C T O R
ST (MAX)
S
N
P
S
10 * 10
I
0.3 * 10
*
2 V
OP
I
2 * 100
C
AC (MAX)
ST (MAX)
V
H E E T
C2
* t
O N T R O L L E R
MIN
V
V
AC (MIN)
O
S
select R3 = 120k.
-3
-3
4
2 V
* 10 * 10
= 61 *
(to keep power dissipation below 0.5W)
= 466k
R3
AC (MIN)
V
where: I
where: I
ST
DETECT
-3
- I
V
V
O
S
ST
= 29µF
OP
winding is used to power the IC
t
V
V
T
= 4T
ST
MIN
ST
ST(MAX)
Maximum dynamic
supply current of the IC
Rise time of the
bootstrap voltage
Minimum hysteresis
voltage
1.7V for 1563)
Maximum start-up
current
Start-up voltage
Maximum start-up
time at AC power-on
(4V for 1562,
Copyright © 1996
Rev. 1.3a
8/30

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