LTC3675_15 Datasheet, PDF (25/38 Pages) Linear Technology – 7-Channel Configurable High Power PMIC

LTC3675/LTC3675-1
Operation
and undervoltage flags. The undervoltage and overtem-
perature faults cannot be masked. A fault that causes
the IRQB pin to be pulled low is latched. When the fault
condition is cleared, the IRQB pin is still maintained in its
low state. The user needs to clear the interrupt by using
a CLRINT command.
On start-up, all PGOOD outputs are unmasked and a power-
on reset will cause RSTB to be pulled low. Once all enabled
regulators have their output PGOOD for 200ms typical
(C_T = 0.01µF) the RSTB output goes Hi-Z.
By masking a PGOOD signal, the RSTB or IRQB pin will
remain Hi-Z even though the output voltage of a regulator
may be below its PGOOD threshold. However, when the
status register is read back, the true condition of PGOOD
is reported.
Undervoltage and Overtemperature
Functionality
The undervoltage (UV) circuit monitors the input sup-
ply voltage and shuts down all enabled regulators if the
input voltage falls below 2.45V. The LTC3675/LTC3675-1
also provide a user with an undervoltage warning, which
indicates to the user that the input supply voltage is ap-
proaching the UV threshold. The undervoltage warning
threshold is user programmable as shown in Table 2.
Table 2. UV Warning Thresholds
UV[2], UV[1], UV[0]
000 (Default)
FALLING V_IN WARNING THRESHOLD
2.7V
001
2.8V
010
2.9V
011
3.0V
100
3.1V
101
3.2V
110
3.3V
111
3.4V
To prevent thermal damage to the LTC3675/LTC3675-1
and its surrounding components, the LTC3675/LTC3675-1
incorporate an overtemperature (OT) function. When the
die temperature reaches 150°C all enabled regulators are
shut down and remain in shutdown until the die tempera-
ture falls to 135°C. The LTC3675/LTC3675-1 also have
an overtemperature warning function which warns a user
that the die temperature is approaching the OT threshold
which allows the user to take any corrective action. The
OT warning threshold is user programmable as shown
in Table 3.
Table 3. OT Warning Thresholds
OT[1], OT[0]
OT WARNING THRESHOLD
00 (Default)
10° Below OT
01
20° Below OT
10
30° Below OT
11
40° Below OT
A UV or OT warning is reported to the user when the IRQB
pin is in its high impedance state. The UV and OT warning
flags are not maskable by the user.
RESET_ALL Functionality: The RESET_ALL bit shuts down
all enabled regulators (enabled either via its enable pin or
I²C) for 1 second. All command registers are cleared and
put in their default state.
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