Datasheet

LTC2978A
35
2978afa
For more information www.linear.com/LTC2978A
TEMPERATURE RELATED COMMANDS
OT_FAULT_LIMIT, OT_WARN_LIMIT, UT_WARN_LIMIT and UT_FAULT_LIMIT
These commands provide supervising limits for temperature.
Data Contents
BIT(S) SYMBOL OPERATION
b[15:0] Ot_fault_limit[15:0],
Ot_warn_limit[15:0],
Ut_warn_limit[15:0],
Ut_fault_limit[15:0]
The data uses the L11 format.
Units: °C.
TIMER LIMITS
TON_DELAY, TON_RISE, TON_MAX_FAULT_LIMIT and TOFF_DELAY
These commands share the same format and provide sequencing and timer fault and warning delays in ms.
TON_DELAY sets the amount of time in milliseconds that a channel waits following the start of an ON sequence before
its V
OUT_EN
pin enables a DC/DC converter. This delay is counted using SHARE_CLK only.
TON_RISE sets the amount of time in ms that elapses after the power supply has been enabled until the LTC2978A’s
DAC soft-connects and servos the output voltage to the desired level if Mfr_dac_mode = 00b. This delay is counted
using SHARE_CLK only.
TON_MAX_FAULT_LIMIT is the maximum amount of time that the power supply being controlled by the LTC2978A
can attempt to power up the output without reaching the VOUT_UV_FAULT_LIMIT. If the output reaches VOUT_UV_
FAULT_LIMIT prior to TON_MAX_FAULT_LIMIT, the LTC2978A unmasks the VOUT_UV_FAULT_LIMIT threshold. If
it does not, then a TON_MAX_FAULT is declared. (Note that a value of zero means there is no limit to how long the
power supply can attempt to bring up its output voltage.) This delay is counted using SHARE_CLK only.
TOFF_DELAY
is the amount of time that elapses after the CONTROLn pin and/or OPERATION command is deasserted
until the channel is disabled (soft-off). This delay is counted using SHARE_CLK if available, otherwise the internal
oscillator is used.
Data Contents
BIT(S) SYMBOL OPERATION
b[15:0] Ton_delay[15:0],
Ton_rise[15:0],
Ton_max_fault_limit[15:0],
Toff_delay[15:0],
The data uses the L11 format.
The internal timers operate on a 10µs internal clock. The SHARE_CLK pin may be used to synchronize the
10µs timer.
Delays are rounded to the nearest 10µs
Units: ms. Max value: 655ms
PMBus COMMAND DESCRIPTION