Toshiba TDP-D1 Service Manual page 102

Lamp Enable - LAMPEN
The DDP1000 electronics provides a lamp enable (LAMPEN) signal to control the projector
lamp and ballast. The LAMPEN is used for on/off control as well as synchronization of AC lamps.
The state of LAMPEN after a reset is low. This is normally the lamp off state of the lamp ballast.
Once PWRGOOD and RESETZ are high and the color wheel is spinning at speed, the DPP1000
electronics drives the LAMPEN high. For AC and DC ballasts it is assumed that the lamp ballast will
ignite the lamp when LAMPEN is driven from low to high. For AC lamps the ballast must drive the
lamp with internal synchronization when LAMPEN is held high. The DDP1000 provides an I2C
lamp disable command. The LAMPEN will be driven low as a result of this command.
Lamp Disable Mode Note: If the End Item product is left in lamp disable mode and the product is
unattended, the possibility of the building power recycling exists. This may cause the End Item
Product to reset the DDP1000 electronics with signal RESETZ. When RESETZ goes back high (and
PWRGOOD is high) the DDP1000 electronics will default LAMPEN to high.
The LAMPEN signal can also be used to synchronize an AC lamp. Once the lamp is lit and
stable a lamp synchronization I2C command can be sent to the DDP1000 electronics. The DDP1000
electronics will respond by outputting lamp synchronization timing on the LAMPEN. The DDP1000
electronics supports three types of lamp synchronization signaling: level, rising edge and rising edge
with feedback. In the level synchronization mode, the level of the LAMPEN controls the direction of
the current to the lamp (Figure 9). This mode typically supports Osram VHP lamp ballasts. The
second type of synchronization is referred to as rising edge. In this mode, the rising edge of the
LAMPEN causes the current to the lamp to alternate (Figure 10). This mode typically supports
Philips Ballasts. The third option is rising edge with feedback. This mode typically supports Philips'
Ballasts that have capability to provide status on the LAMPLITZ signal.
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