Datasheet

ADP1046A Data Sheet
Rev. 0 | Page 14 of 88
THEORY OF OPERATION
The ADP1046A is a secondary side controller for switch mode
power supplies. It is designed for use in isolated redundant
applications. The ADP1046A integrates the typical functions
that are needed to control a power supply, such as
• Output voltage sense and feedback
• Voltage line feedforward control
• Digital loop filter compensation
• PWM generation
• Current sharing
• Current, voltage, and temperature sense
• OrFET control
• Housekeeping and I
2
C interface
• Calibration and trimming
The main function of controlling the output voltage is performed
using the feedback ADCs, the digital loop filter, and the PWM
block.
The feedback ADCs use a multipath approach (patent pending).
The ADP1046A combines a high speed, low resolution (fast and
coarse) ADC with a low speed, high resolution (slow and accurate)
ADC. Loop compensation is implemented using the digital filter.
This proportional, integral, derivative (PID) filter is implemented
in the digital domain to allow easy programming of filter charac-
teristics, which is of great value in customizing and debugging
designs.
The PWM block generates up to seven programmable PWM
outputs for control of FET drivers and synchronous rectification
FET drivers. This programmability allows many traditional and
unique switching topologies to be realized.
A current share bus interface is provided for paralleling multiple
power supplies. The ADP1046A also has hot-swap OrFET sense
and control for N + 1 redundant power supplies.
Conventional power supply housekeeping features, such as remote
and local voltage sense and primary and secondary side current
sense, are included. An extensive set of protections is offered,
including overvoltage protection (OVP), overcurrent protection
(OCP), overtemperature protection (OTP), undervoltage protec-
tion (UVP), ground continuity monitoring (voltage continuity),
and ac sense.
All these features are programmable through the I
2
C bus inter-
face. This bus interface is also used to calibrate the power supply.
Other information that is useful for power monitoring, such as
input current, output current, and fault flags, is also available
through the I
2
C bus interface.
The internal EEPROM can store all programmed values and
allows standalone control without a microcontroller. A free,
downloadable GUI is available and provides all the necessary
software to program the ADP1046A. To obtain the latest software
and a user guide, visit http://www.analog.com/digitalpower.
The ADP1046A operates from a single 3.3 V supply and is
specified from −40°C to +125°C.
RES
VS3–
VS3+
PGOOD1
VDD
GATE PGND ACSNS VS1
OUTA
OUTB
SR1
SR2
OUTC
OUTD
CS1
PSON
SCL
SDA
CS2– CS2+ VS2
VCORE
AGND
OUTAUX
PGOOD2
SHAREi
FLAGIN
DGND
RTDADD
ADC
ADC ADC
ADC
ADC
UVLO
PWM
ENGINE
V
REF
LDO
ADC
ADC
8kB
EEPROM
DIGITAL
CORE
I
2
C
INTERFACE
PWM
OSC
1.2V
+ –
0.45V
+ –
V_OVP
SHAREo
ADP1046A
11012-002
Figure 13. Simplified Block Diagram