Power Management System (Pms) Circuit - NEC MultiSync FP1350 Service Manual

3) Power Management System (PMS) Circuit

PMS circuits reduce power consumption. They have 3 modes of stand-by, suspend and off.
Mode
On
Stand-by
Suspend
Off
a. Stand-by Mode
When the horizontal sync is not input, this monitor enters stand-by mode in a few seconds. The video signal
of IC711 pin 29, 32, 35 are stopped by the video blank signal from IC801 pin 10. Then CPU (IC801) controls
the DAC outputs of the I/O Expander(IC571) to high. (fH1~fH3 and fH5~fH7 becomes high.)
When the horizontal sync is input, this monitor returns to normal operation mode with the shortest
recovery time.
b. Suspend Mode
When the vertical sync is not input, this monitor enters suspend mode in a few seconds. IC801 outputs
pulse(1kHz) from pin 54. Because Q101 and Q102 toggle on-off alternately, LED111,LED112 and
LED113 turn yellow. IC801 pin 22 outputs low to operate each power saving circuit. When the vertical
sync is input to this monitor, it becomes normal operation mode with longer recovery time than stand-by
Mode.
c. OFF mode
When the horizontal sync and vertical sync are not input, this monitor enters off mode in a few seconds.
IC801 pin 8 becomes low, then IC8G2 (5V regulator) turns off.
Table 4 PMS Mode (IC801)
Pin 22 PMS_SUS#
High
High
Low
Low
Pin 8 PMS_OFF#
High
High
High
Low
8-24
Pin 54 POWER LED
Low
Low
Pulse(1KHz)
High