Datasheet

© 2008-2012 Microchip Technology Inc. DS70318F-page 237
dsPIC33FJ06GS101/X02 and dsPIC33FJ16GSX02/X04
19.0 HIGH-SPEED 10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
The dsPIC33FJ06GS101/X02 and
dsPIC33FJ16GSX02/X04 devices provide high-speed
successive approximation analog to digital conversions to
support applications such as AC/DC and DC/DC power
converters.
19.1 Features Overview
The ADC module comprises the following features:
• 10-bit resolution
• Unipolar inputs
• Up to two Successive Approximation Registers
(SARs)
• Up to 12 external input channels
• Up to two internal analog inputs
• Dedicated result register for each analog input
• ±1 LSB accuracy at 3.3V
• Single supply operation
• 4 Msps conversion rate at 3.3V (devices with two
SARs)
• 2 Msps conversion rate at 3.3V (devices with one
SAR)
• Low-power CMOS technology
19.2 Module Description
This ADC module is designed for applications that
require low latency between the request for conversion
and the resultant output data. Typical applications
include:
• AC/DC power supplies
• DC/DC converters
• Power Factor Correction (PFC)
This ADC works with the high-speed PWM module in
power control applications that require high-frequency
control loops. This module can sample and convert two
analog inputs in a 0.5 microsecond when two SARs are
used. This small conversion delay reduces the “phase
lag” between measurement and control system
response.
Up to five inputs may be sampled at a time (four inputs
from the dedicated sample and hold circuits and one
from the shared sample and hold circuit). If multiple
inputs request conversion, the ADC will convert them in
a sequential manner, starting with the lowest order
input.
This ADC design provides each pair of analog inputs
(AN1,AN0), (AN3,AN2),..., the ability to specify its own
trigger source out of a maximum of sixteen different
trigger sources. This capability allows this ADC to
sample and convert analog inputs that are associated
with PWM generators operating on independent time
bases.
The user application typically requires synchronization
between analog data sampling and PWM output to the
application circuit. The very high-speed operation of
this ADC module allows “data on demand”.
In addition, several hardware features have been
added to the peripheral interface to improve real-time
performance in a typical DSP-based application.
• Result alignment options
• Automated sampling
• External conversion start control
• Two internal inputs to monitor INTREF internal
reference and EXTREF input signal
19.3 Module Functionality
The high-speed 10-bit ADC module is designed to
support power conversion applications when used with
the High-Speed PWM module. The ADC may have one
or two SAR modules, depending on the device variant.
If two SARs are present on a device, two conversions
can be processed at a time, yielding 4 Msps conversion
rate. If only one SAR is present on a device, only one
conversion can be processed at a time, yielding 2 Msps
conversion rate. The high-speed 10-bit ADC produces
two 10-bit conversion results in a 0.5 microsecond.
The ADC module supports up to 12 external analog
inputs and two internal analog inputs. To monitor
reference voltage, two internal inputs, AN12 and AN13,
are connected to the EXTREF and INTREF voltages,
respectively.
The analog reference voltage is defined as the device
supply voltage (AV
DD/AVSS).
Block diagrams of the ADC module are shown in
Figure 19-1 through Figure 19-6.
Note 1: This data sheet summarizes the features
of the dsPIC33FJ06GS101/X02 and
dsPIC33FJ16GSX02/X04 families of
devices. It is not intended to be a compre-
hensive reference source. To comple-
ment the information in this data sheet,
refer to Section 44. “High-Speed 10-bit
Analog-to-Digital Converter (ADC)”
(DS70321) in the “dsPIC33F/PIC24H
Family Reference Manual”, which is
available on the Microchip web site
(www.microchip.com).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.