Linear Technology DC1978A, Руководство пользователя

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dc1978af
DEMO MANUAL DC1978A
when the master is down requires supervisors monitoring
the slaves to disable UV detection. Slave UC detection must
also be disabled when the slaves are tracking the master
down to prevent false UC events. All channels configured
for tracking must track off together in response to a fault
on any channel or any other condition that can bring one
or more of the channels down. Prematurely disabling a
slave channel via its run pin may cause that channel to
shut down out of sequence. The LTC2974 supports the
following tracking features:
• Track channels on and off without issuing false UV/
UC events when the slave channels are tracking up or
down.
• Track all channels down in response to a fault from a
slave or master.
• Track all channels down when V
IN_SNS
drops below
VIN_OFF, share clock is held low or RESTORE_USER_
ALL is issued.
• Ability to reconfigure selected channels that are part of
a tracking group to sequence up after the group has
tracked up or sequence down before the group has
tracked down.
To demonstrate the tracking features of LTC2974, DC1810A
has three jumpers (JP1, JP2 and JP3) that can be set to
connect resistive dividers from the 1.8V master supply
(CH0) to the TRACK pins of channels 1 to 3.
The required timing settings and diagrams in order to
enable tracking with LTC2974 are listed in the data sheet,
and a brief summary is shown below:
Master channel 0
• TON_DELAY = Ton_delay_master
• TON_RISE = Ton_rise_master
• TOFF_DELAY = Toff_delay_master
• Mfr_track_en_chan0 = 0
COMMON DEMO BOARD OPERATIONS
Figure 6. LTC2974 Configured to Control, Supervise and Monitor Power Supplies Equipped with Tracking Pin
V
OUTP
RUN
V
OUTM
V
SENSEP0
V
SENSEM0
TRACK
FAULTB0 FAULTB0
LTC2974
CONTROL0
V
OUT_EN0
CONTROL0
DC/DC LOAD
V
OUTP
RUN
V
OUTM
V
SENSEP1
V
SENSEM1
TRACK
V
OUT_EN1
DC/DC LOAD
V
OUTP
RUN
V
OUTM
V
SENSEP2
V
SENSEM2
TRACK
V
OUT_EN2
DC/DC LOAD
V
OUTP
RUN
V
OUTM
V
SENSEP3
V
SENSEM3
TRACK
V
FB
V
DAC0
V
FB
V
DAC1
V
DAC3
V
FB
V
DAC2
V
FB
V
OUT_EN3
V
SENSEP0
V
SENSEP1
V
SENSEP2
V
SENSEM0
V
SENSEM1
V
SENSEM3
V
SENSEM2
V
SENSEP3
DC/DC LOAD
DC1978a F06
R2_3
R1_3
R2_2
R1_2
R2_1
R1_1
PWRGD