參數(shù)資料
型號: TOPP244R
廠商: Power Integrations, Inc.
英文描述: Family Extended Power, Design Flexible,Integrated Off-line Switcher
中文描述: 家庭擴展的電源,設(shè)計靈活,集成的離線切換
文件頁數(shù): 25/48頁
文件大小: 771K
代理商: TOPP244R
TOP242-249
25
August 8, 2000
E
7/01
Processor Controlled Supply Turn On/Off
A low cost momentary contact switch can be used to turn the
TOPSwitch-GX
power on and off under microprocessor control
that may be required in some applications such as printers. The
low power remote off feature allows an elegant implementation
of this function with very few external components as shown in
Figure 45. Whenever the push button momentary contact
switch P1 is closed by the user, the optocoupler U3 is activated
to inform the microprocessor of this action. Initially, when the
power supply is off (M pin is floating), closing of P1 turns the
power supply on by shorting the M pin of the
TOPSwitch-GX
to SOURCE through a diode (remote on). When the secondary
output voltage VCC is established, the microprocessor comes
alive and recognizes that the switch P1 is closed through the
switch status input that is driven by the optocoupler U3 output.
The microprocessor then sends a power supply control signal to
hold the power supply in the on-state through the optocoupler
U4. If the user presses the switch P1 again to command a turn
off, the microprocessor detects this through the optocoupler U3
and initiates a shutdown procedure that is product specific. For
example, in the case of the inkjet printer, the shutdown procedure
may include safely parking the print heads in the storage
position. In the case of products with a disk drive, the shutdown
procedure may include saving data or settings to the disk. After
the shutdown procedure is complete, when it is safe to turn off
the power supply, the microprocessor releases the M pin by
turning the optocoupler U4 off. If the manual switch and the
optocouplers U3 and U4 are not located close to the M pin, a
capacitor C
may be needed to prevent noise coupling to the pin
when it is open.
The power supply could also be turned on remotely through a
local area network or a parallel or serial port by driving the
optocoupler U4 input LED with a logic signal. Sometimes it is
easier to send a train of logic pulses through a cable (due to AC
coupling of cable, for example) instead of a DC logic level as
a wake up signal. In this case, a simple RC filter can be used to
generate a DC level to drive U4 (not shown in Figure 45). This
remote on feature can be used to wake up peripherals such as
printers, scanners, external modems, disk drives, etc., as needed
from a computer. Peripherals are usually designed to turn off
automatically if they are not being used for a period of time, to
save power.
U1
U2
U4
U3
C
M
1 nF
P1
P1 Switch
Status
Power
Supply
ON/OFF
Control
External
Wake-up
Signal
PI-2561-033001
V
(+5 V)
RETURN
CONTROL
MICRO
PROCESSOR/
CONTROLLER
LOGIC
INPUT
LOGIC
OUTPUT
High Voltage
DC Input
+
-
TOPSwitch-GX
D
M
S
F
C
1N4148
U4
LTV817A
6.8 k
100 k
6.8 k
U3
LTV817A
27 k
1N4148
47
μ
F
Figure 45. Remote ON/OFF using Microcontroller.
相關(guān)PDF資料
PDF描述
TOP249R Family Extended Power, Design Flexible,Integrated Off-line Switcher
TOP249Y Family Extended Power, Design Flexible,Integrated Off-line Switcher
TOP242-249 Family Extended Power, Design Flexible,Integrated Off-line Switcher
TOP242G Family Extended Power, Design Flexible,Integrated Off-line Switcher
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