Datasheet

LTC2977
47
2977fa
For more information www.linear.com/LTC2977
An important feature of the LTC2977 is the ability to control, monitor, and supervise DC/DC converters that are con-
figured to track a master supply on and off.
The LTC2977 supports the following tracking features:
•
Track channels on and off without issuing false UV 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 VIN_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.
PMBus COMMAND DESCRIPTION
Figure 13b. Control Pin Tracking All Supplies Up And Down
Figure 13c. Fault on Channel 1 Tracking All Supplies Down
V
OUT2
V
OUT3
VOUT_EN(3:1)
2977 F13b
VOUT_EN0
CONTROL
SLAVE OUTPUT ENABLES TURN ON FIRST SLAVE OUTPUT ENABLES TURN OFF LAST
MASTER BRINGS DOWN
NEXT HIGHEST SLAVE
TON_RISE EXPIRES
FOR ALL CHANNELS.
UV DETECT ENABLED
ON ALL CHANNELS
TOFF_DELAY ENTERED
FOR ALL CHANNELS.
UV DETECT DISABLED
ON ALL CHANNELS
V
OUT1
V
OUT0
V
OUT2
V
OUT3
VOUT_EN(3:1)
2977 F13c
VOUT_EN0
FAULTB0
CONTROL
UV FAULT ON CHANNEL 1 BRINGS DOWN MASTER
VIA FAULTB0. ALL SLAVE CHANNELS INCLUDING
THE ONE WITH THE UV FAULT ENTER TOFF_DELAY
SLAVE OUTPUT ENABLES TURN ON FIRST SLAVE OUTPUT ENABLES TURN OFF LAST
MASTER BRINGS DOWN
NEXT HIGHEST SLAVE
TON_RISE EXPIRES
FOR ALL CHANNELS.
UV DETECT ENABLED
ON ALL CHANNELS
TOFF_DELAY ENTERED
FOR ALL CHANNELS.
UV DETECT DISABLED
ON ALL CHANNELS
V
OUT1
V
OUT0