SCY99194 Datasheet, PDF (3/40 Pages) ON Semiconductor – Fixed Frequency Current Mode Controller

SCY99194
SIMPLIFIED INTERNAL BLOCK SCHEMATIC
LATCH
Vdd
Vhv sample
OVP_CMP
55 us
Filter
OVP
OTP_CMP
VccOVP 10 us
Filter
300 us OTP
Filter
Set Q ^Latch
RESET _{Reset Qb}
VccOVP_CMP
UVLO_CMP
UVLO
ON_CMP
VccON
Vcc_Int
Vdd reg
Vdd
AC_Off
SG & X2 & Vcc
control
TSD
Dual HV
start−up
current source
Vcc regulator
X2 discharge
10.8V regulator
PowerOnReset_CMP
RESET
HV
VCC
FB
CS
GND
VCC
STOP_CMP
VccMIN
Off_mode_CMP1
Set Q ^ICstart
Off_mode_CMP2
Reset Qb
GoToOffMode timer 150ms
jittering
FM input Square output
OSC 65kHz
Vfb(reg)
freq folback
CSref
PFM input Saw output
Ramp_OTA
3.0V
FBbuffer
Skip_CMP
SkipB
4uMho
PWM_CMP
PWM
MAX_ton
IC stopB
Set Q
Reset Qb
VCC
Clamp
V to I
LEB 250ns
SoftStart_CMP
Iopc = 0.5u*(Vhv−125)
Vdd
Vfb < 1.5V fix current setpoint 300mV
Soft Start timer
Enable
SS_end
Ilimit_CMP
Ilimit
Set Q
Fault timer ^Fault
Reset Qb _{Autorecovery timer}
RESET
IC stop
Latch
LEB 120ns
CSstop_CMP
TSD ^TSD
DRV
Figure 2. Simplified Internal Block Schematic
http://onsemi.com
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