SMM766B
Six-Channel Active DC Output Controller, Monitor, Marginer and Sequencer with Sequence-Link
FEATURES & APPLICATIONS
•
Extremely accurate (±0.2%) Active DC Output
Control (ADOC™)
•
Sequence-Link™ provides sequencing of up to
48 channels
•
ADOC automatically adjusts supply output
voltage level under all DC load conditions
•
Monitors, controls, and margins up to 6
supplies from 0.3V to 5.5V with 1.25V Vref
•
Programmable power-on/-off sequencing
•
Operates from any intermediate bus supply
from 6V to 14V and from 2.7V to 5.5V
•
Monitors 12V input VDD and temperature sensor
•
Wide margin/ADOC range from 0.3V to VDD
•
Monitors two general-purpose 10-bit ADC inputs
•
I
2
C 2-wire serial bus for programming
configuration and monitoring status, including
10-bit ADC conversion results
•
2 programmable Under Voltage (UV) and Over
Voltage (OV) threshold limits for each of 11
monitored inputs
•
2k-bit general purpose nonvolatile memory
Applications
•
Monitor/control distributed and POL supplies
•
Multi-voltage processors, DSPs, ASICSs used in
telecom, CompactPCI or server systems
INTRODUCTION
The SMM766B is an Active DC Output power supply
Controller (ADOC
TM
) that monitors, margins, and
cascade sequences. The ADOC feature is unique and
maintains extremely accurate settings of system
supply voltages to within ±0.2% under full load. The
SMM766B actively controls up to 6 DC/DC converters
and can be linked with up to 7 other Sequence-Link™
devices to accommodate sequencing of up to 48
channels. Control of the DC-DC converters is
accomplished through the use of a Trim or Regulator
VADJ/FB pin to adjust the output voltage. For system
test, the part also controls margining of the supplies
using I
2
C commands. It can margin supplies with
either positive or negative control within a range of
0.3V to VDD, depending on the specified range of the
converter. The SMM766B also intelligently sequences
or cascades the power supplies on and off in any
order using enable outputs with programmable
polarity. It can operate off any intermediate bus supply
ranging from 6V to 14V or from 5.5V to as low as 2.7V.
The part monitors 6 power supply channels as well as
VDD, 12V input, two general-purpose analog inputs
and an internal temperature sensor using a 10-bit
ADC. The 10-bit ADC can measure the value on any
one of the monitor channels and output the data via
the I
2
C bus. A host system can communicate with the
SMM766B status register, margining and utilize 2K-
bits of nonvolatile memory.
SIMPLIFIED APPLICATIONS DRAWING
12VIN (+6V to +14V Range)
3.3VIN (+2.7V to +5.5V Range)
12VIN
VDD
SDA
SCL
A2
CAP
A
TRIM_CAP
A
DC/DC
Converter C, E
VIN
DC/DC
Converter A
Vout
TRIM
ON/OFF
12V
3.3V
To additional Sequence-
Link devices
I
2
C
BUS
2.5VIN
SEQ_LINK
External
or
Internal
TEMP
SENSOR
TRIM
A
PUP
A
VM
A
2 of 6 DC-DC
Converters shown
SMM766B
AIN1
CAP
B
TRIM_CAP
B
DC/DC
Converter D, F
VIN
DC/DC
Converter B
Vout
TRIM
ON/OFF
µP/
ASIC
1.2VIN
Environmental
SENSOR
External or
Internal
REFERENCE
AIN2
HEALTHY
VREF
MR#
TRIM
B
PUP
B
RST#
VM
B
HEALTHY
RESET#
READY
Figure 1 – Applications schematic using the SMM766B controller to actively control the output levels of up
to 6 DC/DC converters while also providing power-on/off, cascade sequencing and output margining.
Note: This is an applications example only. Some pins, components and values are not shown.
© SUMMIT
Microelectronics, Inc.
2006 • 757 N. Mary Avenue • Sunnyvale CA 94085 • Phone 408 523-1000 • FAX 408 523-1266
The Summit Web Site can be accessed by “right” or “left” mouse clicking on the link:
http://www.summitmicro.com/
2122 3.0 5/5/2008
1
SMM766B
TABLE OF CONTENTS
General Description………………………...… …………3
Internal Functional Block Diagram……..… ……………4
Pin Descriptions………………………………………..5-6
Package And Pin Configuration………………… ……..7
Absolute Maximum Ratings………………… ………….8
Recommended Operating Conditions……… …..……..8
DC Operating Characteristics………………….. …..8-11
AC Operating Characteristics………………...… …….12
I
2
C 2-Wire Serial Interface AC Operating
Characteristics-100/400khz……………………………13
Timing Diagrams……………………… ……………13-14
DEVICE OPERATION
Power Supply...……………………….……….…… ….15
Modes Of Operation………………………...…… …….15
Active DC Output Control……………………… ….15-16
Power-On Cascade Sequencing….……………….….16
Ongoing Operations-Monitoring Mode……… …...…..17
Temperature Sensor Accuracy………………………..17
Automonitor………………………………………… …..18
Margining…………………………………………… …..18
Power-Off Cascade Sequencing…………… …….…..18
Force-Shutdown….………………………………… ….19
Linked Operation……………………………..…...… …19
Restart…..………………………………………….… …19
I
2
C Power-Off Control………………………...…… …..19
Recommended Use Of The Power On Pin……… ….20
Auto Monitor Function…………………………..….21-25
Under-voltage Lockout………………...….…… ……..26
Applications Schematic…………………………… …..27
Development Hardware & Software………… …...…..28
I
2
C Programming Information
Serial Interface.……………………………………..…..29
Write……………………………………...….…… ……..29
Read….…………………………………………… …….29
Write Protection….……………………….………… ….30
Configuration Registers…..………………………… …30
General-Purpose Memory….……………………… ….30
Command And Status Registers……………………...30
ADC Conversions….………………………….……. ….30
Graphical User Interface (GUI)………………………..30
Write Protection Register Write……………...…… …..31
Configuration Register Read/Write………...… …..31-32
General-Purpose Memory Read/Write……..…… …..33
Command And Status Register Read/Write…… …...34
ADC Conversion Read….……………………… ….….34
Default Configuration Register Settings………. ……..35
Package…………………………………………..… …..36
Part Marking……………………………………...… …..37
Ordering Information…..……………………….… ……37
Terminology And Definitions……………………… …..38
Legal Notice……………………………………………..39
Summit Microelectronics, Inc
2122 3.0 5/5/2008
2
SMM766B
SEQUENCE POSITION
VDD (+2.7V to +5.5V)
or 12VIN ( +8V to +15V)
2.7V
2.5V
2.0V
1.8V
1.5V
1.2V
1
2
3
4
5
Figure 2 – Example power supply sequencing and system start-up initialization using the SMM766B. Cascade
sequencing ensures that all supplies in the previous sequence position are valid before the next channel is
released. Using the SMM766B any order of supply sequencing can be applied.
GENERAL DESCRIPTION
The SMM766B is a highly integrated and accurate
power supply controller, monitor, and sequencer. Each
device has the ability to automatically control, monitor
and cascade sequence up to 6 power supplies. In
addition, the SMM766B includes Sequence-Link a
feature that allows for the seamless integration of
other Sequence-Link devices to accommodate
sequencing of up to 48 channels. The SMM766B can
monitor the VDD input, the 12V input, two general-
purpose analog inputs, and the internal temperature
sensor. The SMM766B has four operating modes:
power-on sequencing mode, monitor mode, supply
margining mode using Active DC Output Control
(ADOC
TM
), and power-off sequencing mode.
Power-on sequencing is initiated by the rising edge of
the PWR_ON pin. During power-on sequencing the
SMM766B will sequence the power supply channels
on, in any order, by activating the PUP outputs and
monitoring the respective converter voltages to ensure
cascading of the supplies. Cascade sequencing is the
ability to hold off the next sequenced supply until the
first supply reaches a programmed threshold. A
programmable sequence termination timer can be set
to disable all channels if the power-on sequence stalls.
Once all supplies have sequenced on and the voltages
are above the UV settings, the ADOC, if enabled, will
bring the supply voltages to their nominal settings.
During this mode, the HEALTHY output will remain
inactive and the RST# output will remain active.
Once the power-on sequencing mode is complete, the
SMM766B enters monitor mode. In the monitor mode,
the SMM766B starts the ADOC control of the supplies
and adjusts the output voltage to the programmed
setting under all load conditions, especially useful for
supplies without sense lines. Typical converters have
±2%
accuracy ratings for their output voltage; the
ADOC feature of the SMM766B increases the
accuracy to
±0.2%
(using a ±0.1% external voltage
reference). The part also enables the triggering of
outputs by monitored fault conditions. The 10-bit ADC
cycles through all 11 channels every 2ms and checks
the conversions against the programmed threshold
limits. The results can be used to trigger RST#,
HEALTHY and FAULT# outputs as well as to initiate a
Fault-Triggered
power-off
or
force-shutdown
operation.
While the SMM766B is in its monitoring mode, an I
2
C
command to margin the supply voltages can bring the
part into margining mode. In margining mode the
SMM766B can margin 6 supply voltages in any
combination of nominal, high and low voltage settings
using the ADOC feature, all to within ±0.2% using a
±0.1% external reference. The margin high and low
voltage settings can range from 0.3V to VDD around
the converters’ nominal output voltage setting
depending on the specified margin range of the DC-
DC converter. During this mode the HEALTHY output
is always active and the RST# output is always
inactive regardless of the voltage threshold limit
settings and triggers. Furthermore, the triggers for
power-off and force-shutdown are temporarily
disabled.
The power-off sequencing mode can only be entered
while the SMM766B is in the monitoring mode. It can
be initiated by either bringing the PWR_ON pin low,
through I
2
C control, or triggered by a channel
exceeding its programmed thresholds. Once power-
off is initiated, it will disable the ADOC function and
sequence the PUP outputs off in the reverse order as
power-on sequencing. To ensure cascading of the
supplies during power-off sequencing all supplies will
be monitored as they turn off.
The sequence
termination timer performs a forced-shutdown
operation if power-off sequencing stalls.
Summit Microelectronics, Inc
2122 3.0 5/5/2008
3
SMM766B
INTERNAL FUNCTIONAL BLOCK DIAGRAM
12VIN
VDD
VDD_CAP
PWR_ON
FS#
3.6V or
5.5V
Regulator
AIN
1
AIN
2
VM
A
CAP
A
Power
Supply
Arbitrator
Cascade
Sequence
Control
SEQ_LINK
PUP
A
PUP
B
PUP
C
PUP
D
PUP
E
PUP
F
10-Bit ADC
Temperature
Sensor
UVLO
Control
VM
F
MR#
CAP
F
RST#
HEALTHY
FAULT#
TRIM
A
TRIM_CAP
A
Output
Control
TRIM
F
TRIM_CAP
F
VREF
FILT_CAP
Active DC
Output
Control
(ADOC
TM
)
Memory, Limit
and Status
Registers
SDA
I
2
C
Interface
SCL
A2
GND
Figure 3 – SMM766B Internal Functional Block Diagram.
Summit Microelectronics, Inc
2122 3.0 5/5/2008
4
SMM766B
PIN DESCRIPTIONS
Pin
Number
1
2
3
Pin
Type
DATA
CLK
IN
Pin Name
SDA
SCL
A2
Pin Description
SDA (Serial Data) is an open drain bi-directional pin used as the I
2
C data
line.
SCL (Serial Clock) is an open drain input pin used as the I
2
C Clock line.
The A2 (Address bit 2) pin is biased either to VDD_CAP or GND. When
communicating with the SMM766B over the 2-wire I
2
C bus, A2 provides a
mechanism for assigning a unique bus address.
MR# (Manual Reset) is an active low input. When asserted the RST# output
will become active. When de-asserted the RST# output will go inactive
immediately after a reset timeout period (t
RTO
) if there are no RST# trigger
sources active. This timeout period makes it suitable to use as a pushbutton
for manual reset purposes.
PWR_ON (Power On) is an open drain bi-directional pin. On the rising edge
of PWR_ON the part will sequence the supplies on, during the falling edge
the part will sequence the supplies off. This pin must be tied high through an
external pull-up resistor.
Note: The SMM766B does not monitor for faults during power-on/off
sequencing.
FS# (Force Shutdown) is an open drain active low bi-directional pin. FS# is
used to immediately turn off all converter enable signals (PUP outputs) when
a fault is detected. Whenever FS# is asserted PWR_ON will automatically be
pulled low as well. This pin must be tied high through an external pull-up
resistor.
The FAULT# pin is an active low open drain output. Active when a
programmed fault condition exists on AIN1, AIN2, or the internal temperature
sensor. When used, FAULT# should be pulled high through an external pull-
up resister.
HEALTHY is an active high open drain output. Active when all programmed
power supply inputs and monitored inputs are within OV and UV limits and
ADOC has begun. When used, HEALTHY should be pulled high through an
external pull-up resistor.
RST# (Reset) is an active low open drain output pin. Active when a
programmed fault condition exists on any power supply inputs or monitored
inputs, when MR# is active, or when ADOC is not ready. RST# has a
programmable timeout period with options for 0.64ms, 25ms, 100ms and
200ms. When used, RST# should be pulled high through an external pull-up
resistor.
AIN1 (Analog Input 1) is a general-purpose monitored analog input.
AIN2 (Analog Input 2) is a general-purpose monitored analog input.
Ground.
4
IN
MR#
5
I/O
PWR_ON
6
I/O
FS#
7
OUT
FAULT#
8
OUT
HEALTHY
9
OUT
RST#
10
11
12
IN
IN
GND
AIN1
AIN2
GND
Summit Microelectronics, Inc
2122 3.0 5/5/2008
5
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