LT1509_15 Datasheet, PDF (1/16 Pages) Linear Technology – Power Factor and PWM Controller

FEATURES
s _{PFC and PWM Single Chip Solution}
s _{Synchronized Operation up to 300kHz}
s _{99% Power Factor over 20:1 Load Current Range}
s _{Current Mode PWM}
s _{Instantaneous Overvoltage Protection}
s _{Dedicated Overvoltage Protection (OVP Pin)}
s _{Minimal Line Current Dead Zone}
s _{Typical 250µA Start-Up Supply Current}
s _{Line Switching Noise Filter}
s _{Low Quiescent Current: 13mA}
s _{Fast 2A Peak Current Gate Drivers}
s _{Separate Soft Start Controls}
U
APPLICATIONS
s _{Universal Power Factor Corrected Power Supplies}
and Preregulators
LT1509
Power Factor and
PWM Controller
DESCRIPTION
The LT ^®1509 is a complete solution for universal off-line
switching power supplies utilizing active power factor
correction. The PFC section is identical to the LT1248 PFC
controller except the EN/SYNC pin is removed because
PFC and PWM are synchronized internally.
The current mode PWM section (the LT1508 is the volt-
age-mode counterpart) contains all the primary side func-
tions to convert the PFC preregulated high voltage output
to an isolated low voltage output. The PWM duty cycle is
internally limited to 47% (maximum 50%) to prevent
transformer saturation. PWM soft start begins when PFC
output reaches the preset voltage. In the event of brief line
loss, the PWM will be shut off when the PFC output voltage
drops below 73% of the preset value.
, LTC and LT are registered trademarks of Linear Technology Corporation.
BLOCK DIAGRAM
V_CC
16V TO 10V
V_SENSE
14
I_AC
9
OVP
11
SS1
16
7.5V
7.9V
14µA
14µA
SS2
13
+
–
–
EA
+
+
–
VA_OUT
10
7.5V
V_REF
V_REF
12
M_OUT I_SENSE
8
7
RUN
7µA
2.2V +
M1
–
I_A
I_M
25k
I_B
I_M =
I_A2I_B
200µA²
–
CA
+
CA_OUT
6
–
+
+
0.7V
–
PWM0K
+
1V
–
7V to
4.7V
–
CL
+
1.2V
–+
4
C_SET
+
–
NOTE: PWM PULSE IS DELAYED BY 55% DUTY CYCLE AFTER PFC PULSE
19
RAMP
18 ^50µA
V_C
GND1
3
PK_LIM V_CC
5 17
R
RQ
RUN _S
OSC
16V
15
R_SET
55%
DELAY
R
SQ
R
200ns
BLANKING
16V
GTDR1
1
GND2
2
GTDR2
20
1500 • BD01
1