Linear Technology DC1978A Manual page 11

DEMO MANUAL DC1978A
COMMON DEMO BOARD OPERATIONS
Slave channel n
• TON_DELAY = Ton_delay_slave
• TON_RISE = Ton_delay_master + Ton_rise_slave
• TOFF_DELAY = Toff_delay_master + T_off_delay_slave
• Mfr_track_en_chan0 = 1
Where:
Ton_delay_master – Ton_delay_slave > RUN to TRACK
setup time
Toff_delay_slave > time for master supply to fall.
PROCEDURE TO DEMONSTRATE TRACKING WITH
DC1978A
1. Start with the default LTC2974 EEPROM and jumper
settings for DC1978A. Set the jumpers JP1, JP2 and
JP3 to TRACK CH0 position. This connects the TRACK
pins of the slave supply channels to the output voltage
of the master channel through resistive dividers (see
Figure 6).
2. Set DC1809A jumper JP4 to SW0 position to propagate
the CONTROL0 switch to the CONTROL0 pin of LTC2974.
3. Set the preload (100mA) of CH0 (SW1 to ON) and the
preloads of the slave channels CH1 to CH3 to OFF (SW2
to SW4 to OFF). The absence of load for the slave chan-
nels makes improper sequencing down behavior more
obvious.
4. Configure all power supplies to respond to CONTROL0,
by setting the appropriate bit in the paged MFR_CONFIG
register. In this case U0:0, U0:1, U0:2 and U0:3 are all
controlled by CONTROL0.
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