Harman Kardon DPR2005 Service Manual page 50

PR1005/DPR2005
D
• SET MDO
5.8 POWER SUPPLY AND POWER ON RESET
During the power on sequence, the reset line must be active during the high voltage supply ramp period. It must be held for a
minimum of 500ms after the supply reaches 95% of its nominal value. The power on rise time of the 46V Power supply MUST NOT
exceed a rise time rate faster than 20V / second. The figure below illustrates the reset timing with power ramp.
POWER SUPPLY RAMP
AND RESET TIMING
0V
Power ON
/RESET
5.9 POWER SUPPLY SEQUENCING
Normal device operation expects the high voltage supply to come up first, with the others following as the regulators activate. The
supplies may be turned on and off in any order without harming the amplifier, however the attached speakers may be damaged by
the transients if the amplifier is not muted. Normal device operation expects the the high voltage supply to decay first, then the other
decay as the regulators drop out.
5.10 OPERATIONAL LIMITATIONS
Do not generate audio output greater than 20kHz with no load. Peaking in the output filter can cause the output voltages to exceed
the filter capacitor voltage rating. Normal audio program material will not have enough energy to cause problems. Avoid test tones
above 20kHz.
5.11 AMPLIFIER OVERLOAD PROTECTION
The amplifier monitors drive currents in each power MOSFET and the heat sink temperature. The current sensors protect the
output stage from over-current and short-circuit faults. The temperature sensor protects the amplifier form excessive operating
temperature. The protection features only affect the speaker output stages. The configuration and register settings are not altered by
amplifier protection actions.
Short duration over-current events, such as produced by a loud program passage or momentary speaker terminal short, will cause the
individual output stage to current limit. The /ERROR output will not report a short duration over-current. Longer duration over-
current events, greater than 250ms, will shut down all speaker output channels and the /ERROR output will be active low. In a dual
zone application, both zones are shut down by a long duration over-current.
Recovery from an over-current shut down is automatic. Approximately 500ms after the over-current shut down, the speaker outputs
will activate. If the condition that caused the shut down persists, the amplifier will shut down in approximately 250ms.
At approximately 100 degress C, the amplifier will shut down all output channels and the /ERROR output will be driven active low
indicating an over-temperature fault. In a dual zone application, both zones are shut down by an over-temperature condition.
Recovery from an over-temperature shut down is automatic. When the amplifier cools to approximately 80 degrees C, the speaker
outputs will activate.
When the amplifier is reset (/RESET input low), or powered down (/PWRDWN low), the /ERROR output will be active low. This
provides an indication that the amplifier is in the reset or power down condition.
GR70 Data Sheet Aug 26, 2003 v1.82
20V / Second Max.
500MS 1000MS 1500MS
High Voltage
Power Supply
.95 Vcc
500MS
2000MS
50
harman/kardon
CONSUMER
17