CS1500-FSZ Cirrus Logic Inc, CS1500-FSZ Datasheet - Page 9

• Manufacturer Part Number: CS1500-FSZ
• Description: IC PFC CONTROLLER DCM 8SOIC
• Manufacturer: Cirrus Logic Inc
• Series: EXL Core™r

Specifications of CS1500-FSZ

• Package / Case: 8-SOIC (3.9mm Width)
• Mode: Discontinuous Conduction (DCM)
• Frequency - Switching: 66kHz
• Current - Startup: 68µA
• Voltage - Supply: 7.9 V ~ 17 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Switching Frequency: 70 KHz
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 598-1800

5.4 Output Power and PFC Boost Inductor
In normal operating mode, the nominal output power is
estimated by the following equation.
where:
P
V
V
f
L
Equation 1 is provided for explanation purposes only. Using
substituted required design values for V
following equation.
Changing values for application-specific devices such as the
boost inductor or V
requires changing internal register values.
Solving Equation 2 for the PFC boost inductor L
following equation.:
If a value of the boost inductor other than that obtained from
Equation 3 above is used, the total output power capability as
well as the minimum input voltage threshold will differ
according to Equation 2.
DS849F1
max
Figure 15. Relative Effects of Varying Boost Inductance
B
o
in(min)
link
P
o
L
P
o
B
=
=
=
by the PFC algorithm)
against boost inductor tolerances.
rated output power of the system
efficiency of the boost converter (estimated as 100%
minimum RMS line voltage is 90V, measured after
the rectifier and EMI filter
nominal PFC output voltage must be 400 V
maximum switching frequency is 70 kHz
boost inductor specified by rated power requirement
margin factor to guarantee rated output power (P
V
90V
90V
in min
link
90
2
2
voltage is not recommended and
2
------------------------------------------------------------ -
2
------------------------------------------------------------ -
2
V
400V
AC(rms)
400V
V
-------------------------------------------------------- -
70kHz P
2 f
70kHz
link
L < L
L > L
–
–
max
–
L = L
90V
V
90V
in min
B
B
link
L
o
B
L
B
B
and f
400V
400V
2
V
2
link
CONFIDENTIAL
max
2
265
B
gives the
gives the
[Eq.1]
[Eq.2]
[Eq.3]
o
)
5.5 PFC Output Capacitor
The value of the PFC output capacitor should be chosen
based upon voltage ripple and hold-up requirements. To
ensure system stability with the digital controller, the
recommended value of the capacitor is within the range of
0.5 F / watt to 2.0 F / watt.
5.6 Output IFB Sense & Input IAC Sense
A current proportional to the PFC output voltage, V
supplied to the IC on pin IFB and is used as a feedback control
signal. This current is compared against an internal fixed-
value current.
The ADC is used to measure the magnitude of the I
through resistor R
compared to an internal fixed-value current.
Resistor R
follows:
By using digital loop compensation, the voltage feedback
signal does not require an external compensation network.
A current proportional to the AC input voltage is supplied to the
IC on pin IAC and is used by the PFC control algorithm.
Resistor R
For optimal performance, resistors R
tolerance or better resistors.
IAC
Figure 16. Feedback Input Pin Model
IFB
V
I
FB
R
I
rec t
AC
Figure 17. IAC Input Pin Model
sets the IAC current and is derived as follows:
sets the feedback current and is calculated as
IFB
IFB
=
. The magnitude of the I
R3
R4
V
--------------------------- -
R1
R2
link
R
I
R
IFB
fixed
R
IA C
IAC
IFB
–
IAC
V
4
3
dd
=
R
=
7
IFB
7
15k
V
15k
V DD
24k
400V V
----------------------------- -
V DD
IAC
link
24k
129 A
& R
–
IFB
CS1500
CS1500
FB
ADC
dd
ADC
should use 1%
CS1500
current is then
FB
current
[Eq.4]
link
[Eq.5]
, is
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