TOP264-271
X Pin
I
REM(N)
(Enabled)
Output
MOSFET
Switching
I
UV
V Pin
I
OV
I
OV(LS)
(Non-Latching)
(Disabled)
Disabled when supply
output goes out of
regulation
I
LIMIT
(Default)
(Latching)
I
Current
Limit
I
DC
MAX
(78%)
Maximum
Duty Cycle
I
V
BG
Pin Voltage
-250
-200
-150
-100
-50
0
25
50
75
100
125
336
I
X and V Pins Current (µA)
Note: This figure provides idealized functional characteristics with typical performance values. Please refer to the parametric
table and typical performance characteristics sections of the data sheet for measured data. For a detailed description of
each functional pin operation refer to the Functional Description section of the data sheet.
Figure 8.
VOLTAGE MONITOR and EXTERNAL CURRENT LIMIT (E and V package) Pin Characteristics.
PI-5528-060409
section above) and runs entirely off the high voltage DC input,
but with very low power consumption (<100 mW typical at
230 VAC with X pin open). When the TOP264-271 is remotely
turned on after entering this mode, it will initiate a normal
start-up sequence with soft-start the next time the CONTROL
pin reaches 5.8 V. In the worst case, the delay from remote-on
to start-up can be equal to the full discharge/charge cycle time
of the CONTROL pin, which is approximately 125 ms for a
47
mF
CONTROL pin capacitor. This reduced consumption
remote off mode can eliminate expensive and unreliable in-line
mechanical switches. It also allows for microprocessor
controlled turn-on and turn-off sequences that may be required
in certain applications such as inkjet and laser printers.
Soft-Start
The 17 ms soft-start sweeps the peak drain current and switching
frequency linearly from minimum to maximum value by operating
through the low frequency PWM mode and the variable
frequency mode before entering the full frequency mode. In
addition to start-up, soft-start is also activated at each restart
attempt during auto-restart and when restarting after being in
hysteretic regulation of CONTROL pin voltage (V
C
), due to
remote OFF or thermal shutdown conditions. This effectively
minimizes current and voltage stresses on the output MOSFET,
the clamp circuit and the output rectifier during start-up. This
feature also helps minimize output overshoot and prevents
saturation of the transformer during start-up.
9
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Rev. B 03/10
POWERINT [ POWER INTEGRATIONS, INC. ]
