UCC28600 Datasheet, PDF (7/25 Pages) Texas Instruments – 8-PIN QUASI-RESONANT FLYBACK GREEN MODE CONTROLLER

UCC28600
www.ti.com
SLUS646B – NOVEMBER 2005 – REVISED MAY 2006
TERMINAL COMPONENTS
TERMINAL
NAME
NO.
CS
3
FB
2
GND
4
OUT
5
I/O DESCRIPTION^(1)(2)(3)
ǒ Ǔǒ Ǔ _{VPL * VCS(os) ICS(2) * ICS(1)}
R_CS +
I_CS(2)I_P(1) * I_CS(1)I_P(2)
ǒ Ǔǒ Ǔ _{VPL * VCS(os) IP(2) * IP(1)}
R_PL +
I_CS(1)I_P(2) * I_CS(2)I_P(1)
I
where:
• I_P1 is the peak primary current at low line, full load
• I_P2 is the peak primary current at high line, full load
• I_CS1 is the power limit current that is sourced at the CS pin at low-line voltage
• I_CS2 is the power limit current that is sourced at the CS pin at high-line voltage
• V_PL is the Power Limit (PL) threshold
• V_CS(os) is the CS offset voltage
I Opto-isolator collector
- Bypass capacitor to VDD, C_BP = 0.1 µF
O Power MOSFET gate
ǒ Ǔ R_OVP1
+
1
I_OVP(lineth)
N_B
N_P
V_BULK(ov)
OVP
ȧȧȡȢ _{ǒ Ǔ} ȧȧȣȤ R_OVP2 + R_OVP1
N_B
N_S
V_{OVP(load th)}
V_OUT(ov) ) V_F * V_{OVP(load th)}
7
I
where:
• I_{OVP(line th)} is OVP_line current threshold
• V_BULK(ov) is the allowed input over- voltage level
• V_{OVP(load_th)} is OVP_load
• V_OUT(ov) is the allowed output over-voltage level
• V_F is the forward voltage of the secondary rectifier
• N_B is the number of turns on the bias winding
• N_S is the number of turns on the secondary windings
• N_P is the number of turns on the primary windings
(1) Refer to Figure 1 for all reference designators in the Terminal Components Table.
(2) Refer to the Electrical Characteristics Table for constant parameters.
(3) Refer to the UCC28600 Design Calculator (TI Literature Number SLVC104) or laboratory measurements for currents, voltages and times
in the operational circuit.
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