CS1601 Datasheet, PDF (14/16 Pages) Cirrus Logic – Digital PFC Controller for Electronic Ballasts

CS1601
5.15 Summary of Equations
Eq. #
1
Equation
Output Power (page 10)
P_o =     V_{inmin}²  ^V---₂--^l-ⁱ--ⁿ_--^k---_f-–_m-----_a^--^V-_x---ⁱ-_-ⁿ---^-_L-^m---_B-ⁱ-ⁿ--_-^---_V^-----_l-_i-_n--²-_k---^-
P_o

Output Power w/ recommended values (page 10)
Variables/Recommended Values
Rated output power of the system.
Efficiency of the boost converter (estimated as
100% by the PFC algorithm).
2
P_o =     90Vrms²  ⁴-₂---⁰--_-⁰----_7V---₀--–--_k---^_H--⁹---_z-⁰---_^V-----^r-_L-^m--_B---^s-_----^-4---0---0--²-_V---^
V_in(min) Minimum RMS line voltage is 90Vrms,
measured after the rectifier and EMI filter.
Boost Inductor (page 10)
V_link
Nominal PFC output voltage must be 400V.
3
L_B =     90Vrms²  -⁴²---⁰--_-⁰---₇-^V---₀--–-_k----_H^--⁹---_z-⁰---_^V-----^rP--^m_o-----^s-_----^-4---0---0--²-_V---^
f_max
Maximum switching frequency is 70kHz.
Output IFB Sense Resistor (page 11)
L_B
Boost inductor specified by rated power
requirement.
4
R_IFB = ^V-----^l-ⁱ-ⁿ---^k-_I--_r-–-_e---_f-^V----^D----^D-- = -⁴---⁰---⁰¹----_2V---₉--–--_---^VA----^D----^D--

Margin factor to guarantee rated output power
(P_o) against boost inductor tolerances.
Input IAC Sense Resistor (page 11)
5
R_IAC = R_IFB
R_IAC Value of the IAC pin sense resistor(s).
Auxiliary Winding Cut-off Frequency (page 12) _RIFB
Value of the IFB pin sense resistor(s).
6
f_c = 1  2R3  R4C_p
I_ref
Value of the fixed, internal reference current.
Maximum Response Time for Brownout: (page 12)
7
T_Brownout = 8 ms + ⁸--₅---^m--_V---^s- 128 V – V_{BPth} + 56 ms
f_c
The cut-off frequency, f_c, needs to be 10x the
ringing frequency or f_c = 10MHz.
Overvoltage Protection (page 12)
C_p
Capacitance at the ZCD pin. C_p<10pF.
8
V_OVP = R_IFB  I_OVP + V_DD
V_BP(th) Brownout threshold voltage. V_BP(th) = 94.8V.
Boost Inductor Peak Current
9
I_{LBpk}
=
--------------⁴-----^-----^P----^O---------------
  V_{inmin}  2
C_out
Value of the output capacitor in microfarads.
f_line(min) Minimum line frequency.
Boost Inductor RMS Current
10
I_{LBrms} = _V-----_i-_n---_--_m-^P---_i-^O-_n---_---_----_--
V_DD
IC Supply Voltage.
V_link Voltage Ripple
V_OVP OVP threshold.
11
V_{linkrip} = ₂----_-----_-----_f--_l-_i-_n---_e---_--_m-----_i-_n-^P--_--^O-_-----_V----_l-_i--_n---_k---_-----_C-----_o---_u--_t
I_OVP
Current into the IFB pin.
14
DS931PP6