SMM764 SUMMIT Microelectronics, Inc:, SMM764 Datasheet - Page 16

• Manufacturer Part Number: SMM764
• Description: Four-channel Active Dc Output Controller, Monitor, Marginer And Sequencer With Sequence-link
• Manufacturer: SUMMIT Microelectronics, Inc:

sequence position. Any unused channel should be
assigned to the null sequence position.
ONGOING OPERATIONS-MONITORING MODE
During ongoing operations mode, the part can monitor,
and actively control via ADOC, and use the force-
shutdown operation if necessary.
Once the power-on sequence is complete, depending
on the user programmed settings; the SMM764 will
either enter the ongoing operations mode directly or
wait for ADOC to successfully bring all channels within
their nominal values. The ongoing operations mode
will end when a power-off sequence, or force-
shutdown has been initiated.
Once the ongoing operations mode has begun, the
SMM764 continues to monitor all VM
and 12VIN inputs, and two temperature sensor inputs
with a 10-bit ADC. Each of these inputs is sampled
and converted by the ADC every 2ms. The ADC input
has a range of 0V to four times the voltage on VREF
for inputs VM
extended to 12 times VREF for the 12VIN input and is
reduced to two times VREF for the AIN1 and AIN2
inputs.
The SMM764 monitors internal temperature using the
10-bit ADC and the automonitor function. Two under-
temperature and two over-temperature thresholds can
be set, each with its own programmable threshold
options and consecutive conversion, before trigger
counter. Resolution is 0.25 C per bit scaled over the
range of
can be acquired over the I
two's complement value.
The
conversion with two programmable 10-bit under-
voltage limits (UV1, UV2) and two programmable 10-
bit
corresponding input.
counter is used to provide filtering of the ADC inputs.
Each limit can be programmed to require 1, 2, 4 or 6
consecutive out-of-limit conversions before it is said to
be in fault. One in-limit conversion will remove the
fault from the threshold limit.
filtering of the monitored inputs. The ADC inputs VM
can use additional filtering by connecting a capacitor
from the corresponding CAP
an analog RC filter (R=25kΩ). The input is considered
to be in a fault condition if any of its limit thresholds
are in fault. Setting an OV threshold limit to full-scale
(3FF
ensures that the limit can never be in fault. The status
Summit Microelectronics, Inc
APPLICATIONS INFORMATION (CONTINUED)
HEX
over-voltage
SMM764
), or setting a UV threshold limit to 000
-128 C to 127.75 C. The temperature value
A-D
and the VDD input. The range is
compares
limits
A consecutive conversion
2
C bus as a 10-bit signed
(OV1,
X
each
pins to ground to form
This provides digital
X
OV2)
resulting
inputs, the VDD
for
ADC
HEX
the
A-D
2098 1.1 6/29/2005
,
registers provide the real-time status of all monitored
inputs.
The voltage threshold limits for inputs VM
12VIN can be programmed to trigger the RST# and
HEALTHY outputs as well as a Fault-Triggered force-
shutdown and power-off operation when exceeded.
The threshold limits for the internal temperature
sensor and the AIN1 and AIN2 inputs can be
programmed to assert the RST#, HEALTHY, and
FAULT# output pins
The HEALTHY and FAULT# outputs of the SMM764
are active as long as the monitored threshold remains
in violation. The RST# output also remains active as
long as the monitored threshold remains in violation.
However, once the threshold violation goes away, the
RST# will remain active for a programmable reset
timeout period (t
The
shutdown and power-off operations, those caused by
I
PWR_ON pin, differently than those caused by a
Fault-Triggered
conditions, those caused by UV/OV violations or a
sequence termination timer expiration. The mode in
which either a forced-shutdown or a power-off occurs
effects how or whether the SMM764 will restart, and
the number of allowable retries permitted.
TEMPERATURE SENSOR ACCURACY
The internal temperature sensor accuracy is ±5
-40 to +85
of the SMM764 die and the ambient temperature. If
VDD is at 5V, the die temperature is +2
it is +4
specific applications, measure the VDD or 12VIN
supply current and calculate the power dissipated and
multiply by 80
25mW, which creates a 2
MARGINING
The SMM764 has two additional ADOC voltage
settings for channels A-D, margin high and margin
low. The margin high and margin low voltage settings
can range from 0.3V to VDD of the converters’
nominal output voltage, depending on the specified
margin range of the DC-DC converter.
settings are stored in the configuration registers and
are loaded into the ADOC voltage setting by margin
commands issued via the I
be enabled for ADOC in order to enable margining.
The margin command registers contain two bits for
2
C commands and assertion of the FS# and
SMM764
o
C.
o
C. The sensor measures the temperature
In order to calculate this difference in
o
C/W. For instance, 5V and 5mA is
PRTO
treats
forced-shutdown
).
o
Command-Triggered
C offset.
2
C bus. The channel must
Preliminary Information
and
SMM764
o
C and at 12V,
A-D
, VDD and
power-off
o
C from
These
force-
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