Cirrus Logic CS1501 - Manual (Page 14)

CS1501
14 DS927F4
5.15 Summary of Equations
Eq. # Equation Variables/Recommended Values
1
Output Power ( page 10 )
P
o
Rated output power of the system.
 Efficiency of the boost converter (estimated as
100% by the PFC algorithm).
V
in(min)
Minimum RMS line voltage is 90Vrms,
measured after the rectifier and EMI filter.
V
link
Nominal PFC output voltage must be 400V.
f
max
Maximum switching frequency is 70kHz.
L
B
Boost inductor specified by rated power
requirement.
 Margin factor to guarantee rated output power
(P
o
) against boost inductor tolerances.
R
IAC
Value of the IAC pin sense resistor(s).
R
IFB
Value of the IFB pin sense resistor(s).
I
ref
Value of the fixed, internal reference current.
f
c
The cut-off frequency, f
c
, needs to be 10x the
ringing frequency or f
c
= 10MHz.
C
p
Capacitance at the ZCD pin. C
p
<10pF.
V
BP(th)
Brownout threshold voltage. V
BP(th)
= 94.8V.
C
out
Value of the output capacitor in mF.
f
line(min)
Minimum line frequency.
V
DD
IC Supply Voltage.
V
OVP
OVP threshold.
I
OVP
Current into the IFB pin.
2
Output Power with recommended values ( page 10 )
3
Boost Inductor ( page 10 )
4
Output IFB Sense Resistor ( page 11 )
5
Input IAC Sense Resistor ( page 11 )
6
Auxiliary Winding Cut-off Frequency ( page 11 )
7
Maximum Response Time for Brownout: ( page 12 )
8
Overvoltage Protection ( page 12 )
9
Boost Inductor Peak Current
10
Boost Inductor RMS Current
11
V
link
Voltage Ripple
P
o
  V
in min  
  
2

V
link
V
in min  
2    –
2 f
max
L
B
V
link
  
---------------------------------------------------------  =
P
o
  90Vrms   
2

400V 90Vrms 2    –
2 70kHz L
B
400V   
-------------------------------------------------------------  =
L
B
  90Vrms   
2

400V 90Vrms 2    –
2 70kHz P
o
400V   
-------------------------------------------------------------  =
R
IFB
V
link
V
DD
–
I
ref
-----------------------------
400V V
DD
–
129 A
------------------------------- = =
R
IAC
R
IFB
=
f
c
1 2  R3 R4   C
p
   =
T
Brownout
8 ms
8 ms
5 V
------------ 128 V V
BP th  
–   56 ms + + =
V
OVP
R
IFB
I
OVP
 V
DD
+ =
I
LB pk  
4 P
O

 V 
in min  
2 
-------------------------------------------- =
I
LB rms  
P
O
V
in min  
 
------------------------------ =
V
link rip  
P
O
2  f
line min  
 V
link
 C
out

------------------------------------------------------------------------ =