ALTAIR04-900TR Просмотр технического описания (PDF) - STMicroelectronics
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ALTAIR04-900TR Datasheet PDF : 29 Pages
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Pin connection
2
Pin connection
ALTAIR04-900
Figure 2. Pin connection (top view)
SOURCE 1
SOURCE 2
Vcc 3
GND 4
IREF 5
ZCD/FB 6
COMP 7
N.A. 8
16 DRAIN
15 DRAIN
14 DRAIN
13 DRAIN
12 N.C.
11 N.A.
10 N.A.
9 N.A.
Note:
The copper area has to be placed under the drain pins to dissipate heat.
Table 1. Pin functions
Number Name
Function
Power section source and input to the PWM comparator. The current, flowing through
MOSFET, is sensed by a resistor connected between the pin and GND. The resulting voltage
1, 2
SOURCE
is compared with an internal reference (0.75 V max.) to determine the MOSFET turn-off. The
pin is equipped with 250 ns blanking time, after the gate-drive output goes high for noise
immunity. If a second comparison level located at 1 V is exceeded the IC is stopped and
restarted after Vcc has dropped below 5 V.
Supply voltage of the device. An electrolytic capacitor, connected between this pin and
ground, is initially charged by the internal high voltage start-up generator; when the device
3
Vcc
runs, the same generator keeps it charged if the voltage, supplied by the auxiliary winding, is
not sufficient. This feature is disabled if a protection is tripped. Sometimes a small bypass
capacitor (0.1 µF typ.) to GND might be useful to get a clean bias voltage for the signal part
of IC.
Ground. Current return both for IC signal part and the gate-drive. All ground connections of
4
GND bias components should be tied to a trace and kept separated from any pulsed current
return.
CC regulation loop reference voltage. An external capacitor has to be connected between
5
IREF
this pin and GND. An internal circuit develops a voltage on this capacitor used as the
reference for peak drain current of the MOSFET during CC regulation. The voltage is
automatically adjusted to keep the average output current constant.
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DocID18211 Rev 3
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