ADM1041-EVAL Analog Devices Inc, ADM1041-EVAL Datasheet - Page 3

• Manufacturer Part Number: ADM1041-EVAL
• Description: BOARD EVALUATION ADM1041
• Manufacturer: Analog Devices Inc

Specifications of ADM1041-EVAL

• Main Purpose: AC/DC, Secondary Side
• Outputs And Type: 1, Non-Isolated
• Power - Output: 24W
• Voltage - Output: 12V
• Current - Output: 2A
• Voltage - Input: 85 ~ 132VAC
• Board Type: Fully Populated
• Utilized Ic / Part: ADM1041
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Frequency - Switching: -
• Regulator Topology: -
• Lead Free Status / Rohs Status: Not Compliant

GENERAL DESCRIPTION
The ADM1041 is a secondary-side and management IC specifi-
cally designed to minimize external component counts and to
eliminate the need for manual calibration or adjustment on the
secondary-side controller. The principle application of this IC is
to provide voltage control, current share, and housekeeping
functions for single output in N+1 server power supplies.
The ADM1041 is manufactured with a 5 V CMOS process and
combines digital and analog circuitry. An internal EEPROM
provides added flexibility in the trimming of timing and voltage
and selection of various functions. Programming is done via an
SMBus serial port that also allows communication capability
with a microprocessor or microcontroller.
The usual configuration using this IC is on a one per output
basis. Outputs from the IC can be wire-ORed together or bused
in parallel and read by a microprocessor. A key feature on this
IC is support for an OrFET circuit when higher efficiency or
power density is required.
SAMPLE APPLICATION CIRCUIT DESCRIPTION
Figure 1 shows a sample application circuit using the ADM1041.
The primary side is not detailed and the focus is on the secon-
dary side of the power supply.
The ADM1041 controls the output voltage from the power
supply to the designed programmed value. This programmed
value is determined during power supply design and is digitally
adjusted via the serial interface. Digital adjustment of the
current sense and current limit is also calibrated via the serial
interface, as are all of the internal timing specifications.
The control loop consists of a number of elements, notably the
inputs to the loop and the output of the loop. The ADM1041
takes the loop inputs and determines what, if any, adjustments
COUPLER
OPTO-
PRIMARY
DRIVER
PWM +
AND FAULT DETECTION
VOLT, TEMP MONITOR
ADM1041
ERROR
AC PULSE
AMP
SENSE
Figure 2. Application Block Diagram
START
SOFT
Rev. A | Page 3 of 64
DIFF CURRENT
RAM AND TRIM
EEPROM AND
SENSE
R
SENSE
DIFF LOAD AND LOCAL
VOLTAGE SENSE
are needed to maintain a stable output. To maintain a stable
loop, the ADM1041 uses three main inputs:
•
•
•
In this example, a resistor divider senses the output current as a
voltage drop across a sense resistor (RS) and feeds a portion
into the ADM1041. Remote local voltage sense is monitored via
V
back via the share bus. These three elements are summed
together to generate a control signal (V
loop via an optocoupler to the primary side PWM controller.
Another key feature of the ADM1041 is its control of an OrFET.
The OrFET causes lower power dissipation across the ORing
diode. The main function of the OrFET is to disconnect the
power supply from the load in the event of a fault occurring
during steady state operation, for example, if a filter capacitor or
rectifier fails and causes a short. This eliminates the risk of
bringing down the load voltage that is supplied by the redun-
dant configuration of other power supplies. In the case of a
short, a reverse voltage is generated across the OrFET. This
reverse voltage is detected by the ADM1041 and the OrFET is
shut down via the F
interruption on the power supply bus. The ADM1041 can then
be interrogated via the serial interface to determine why the
power supply has shut down.
This application circuit also demonstrates how temperature can
be monitored within a power supply. A thermistor is connected
between the V
with temperature. The MON2 input can be programmed to trip
a flag at a voltage corresponding to an overheating power supply.
The resulting action may be to turn on an additional cooling
fan to help regulate the temperature within the power supply.
S
+ and V
Remote voltage sense
Load current sense
Current sharing information
CONTROL
CURRENT
SMBus
OrFET
SHARE
S
− pins. Finally, current sharing information is fed
DD
and MON2 pins. The thermistor’s voltage varies
(µC OR STANDALONE
G
pin. This intervention prevents any
OPERATION)
LOAD
SHARE
µC
BUS
CMP
), which closes the
ADM1041