MAX11014_08 Datasheet, PDF (56/70 Pages) Maxim Integrated Products – Automatic RF MESFET Amplifier Drain-Current Controllers

Automatic RF MESFET Amplifier
Drain-Current Controllers
ACTUAL MEASUREMENT
VALUE, THEREFORE
ALARM TRIGGERS
ALARM TRIGGERED
WHEN EXCEEDING
THIS LEVEL
1111 1111 1111
MOST POSITIVE VALUE
(DEFAULT FOR HIGH
THRESHOLD REGISTERS)
HIGH THRESHOLD
REGISTER VALUE
ALARM REMOVED
AFTER CROSSING
BACK BELOW THIS
LEVEL
WINDOW OF VALUES THAT DO NOT TRIGGER AN ALARM
LOW THRESHOLD
REGISTER VALUE
Figure 26. ALARM Hysteresis Comparator Example
0000 0000 0000
MOST NEGATIVE VALUE
(DEFAULT FOR LOW
THRESHOLD REGISTERS)
ALARM Output
The ALARM output asserts when the corresponding
channel’s temperature or voltage readings exceed the
respective high or low ALARM threshold. Each time the
sense voltage, temperature (external for either channel,
internal for channel 2), or GATE_ voltage is converted,
the measured value is compared to the high and low
ALARM threshold values.
The ALARM comparison operates in either window or
hysteresis mode. When operating in window compara-
tor mode (TWIN_, IWIN_, or VGWIN_ bits in the soft-
ware ALARM configuration register set to 1), the ADC
output values are monitored to ensure that the values
are between both the high and low ALARM threshold
register values. See Table 13 and Figure 24.
Window comparisons include built-in hysteresis levels,
ensuring the ALARM output does not trigger repeatedly
when sampling values around the threshold. The
ALMHYST bits in the hardware ALARM configuration
register vary the built-in hysteresis between 8 and 64
LSBs. The built-in hysteresis acts as a noise filter to
prevent unnecessary switching when a sample value is
varying slightly around the threshold. The ALARM con-
dition remains in place until the measured value rises
above the low threshold value or falls below the high
threshold value. Figure 25 details a window-mode tim-
ing example.
The ALARM output operates in interrupt or comparator
mode. In interrupt mode, the ALARM output asserts until
the ALARM flag register is read. In comparator mode,
the ALARM output reflects the internal ALARM state and
remains asserted for as long as the ALARM conditions
are breached. The ALARM output deasserts after the
windowing or hysteresis conditions are satisfied.
When operating in hysteresis comparator mode (TWIN_,
IWIN_, or VGWIN_ bits in the software ALARM configura-
tion register set to 0), the ADC output values are moni-
tored to ensure that the values are below the high set
56 ______________________________________________________________________________________