FMS2701
PRODUCT SPECIFICATION
15
P
Note that setting the INT output by exceeding a temperature
limit is an edge-driven event. Only when the temperature
actually crosses the limit boundary does INT\ transition LOW.
An example of interrupts caused by a series of temperature,
T transitions across temperature limits is shown in Figure 10.
Temperature limits are fixed for the first series of temperature
excursions. Then, for the second series, following the THI1
violation, the THI limit is raised from THI1 to THI2. If THI
is reprogrammed from a value above T to a value below THI,
then an interrupt is generated. INT is cleared by reading the
Interrupt Status Register (ISRread).
Figure 10. Profile of Temperature Driven Interrupts
INT
T
T
HI1
T
HI2
T
HI3
T
LO1
T
LO2
ISRread
ATV and RTV bits operate in conjunction with the INT
output and Interrupt status Register as follows:
1.
When the temperature exceeds a high limit, the corre-
sponding Interrupt Status Register bit, either ATV or
RTV is set.
Reading the Interrupt Status Register clears ATV and RTV.
Once the high limit has been exceeded, a subsequent
transitions through the high level will not cause an
interrupt, unless:
a) The temperature passes through the low limit.
b) Or, the high temperature limit is changed.
If the high temperature limit is changed from a level
above the temperature to a level below, then the relevant
Interrupt Status Register bit, either ATV or RTV is set.
If the temperature falls below a low limit, the corre-
sponding Interrupt Status Register bit, either ATV or
RTV is set.
Once the low limit has been exceeded, a subsequent
transitions through the low level will not cause an inter-
rupt, unless:
a) The temperature passes through the high limit.
b) Or, the low temperature limit is changed.
If the low temperature limit is changed from a level
below the ambient/remote temperature to a level above,
then the ATV/RTV bit is set.
2.
3.
4.
5.
6.
7.
GPI—General Purpose Input
GPI is a General Purpose Input that can be used to trigger an
interrupt. Configuration Register bit GPI_INVT determines
the polarity of the GPI input. Interrupt Register bit, GPI = H
sets output INT = L if Mask Register bit MSK_GPI = L.
Limit and Trip Point Comparators
Temperature register outputs, TR
7-0
and TA
7-0
are compared
with the limit values TRHI
7-0
, TRLO
7-0
, TAHI
7-0
and TALO
7-0
that are stored in the Limit Registers. Out of range TA
7-0
and
TR
7-0
values set the INT bit in the Interrupt Status Register.
TR
7-0
and TA
7-0
are also compared with the values in Trip
Point Registers, PTA
7-0
and PTR
7-0
if these registers have
been loaded or FTA
7-0
and FTR
7-0
, which contain power up
default values. If a trip point is violated, two outputs are
asserted: THERM = L and FAN_SPD = H.
Mask Gating
Setting the corresponding bit in the Interrupt Mask Register
can mask any bit in the Interrupt Status Register.
Timing and Control
Timing and Control logic generates a master clock and
orchestrates on-chip timing.
NAND Gate Test
A selectable NAND tree test is provided for Automated Test
Equipment (ATE) board level connectivity testing. NAND
tree test mode is enabled by setting the input pin, FAN_SPD
NTEST_IN = H, while the AUXRST output transitions L to H,
causing the output of a D flip-flop to:
1.
Enable the NAND tree output, connecting it to the
ADD/NTEST_OUT pin.
2.
Disable the D/A converter output to the FAN/SPD
NTEST_IN.
To perform a NAND tree test, NAND tree pins should be
driven high.
Each pin is toggled in turn to generate an output pattern with
values that can be verified against those shown in Table 4.