Datasheet

 2011-2012 Microchip Technology Inc. DS75018C-page 225
dsPIC33FJ06GS001/101A/102A/202A and dsPIC33FJ09GS302
19.0 HIGH-SPEED 10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
The dsPIC33FJ06GS001/101A/102A/202A and
dsPIC33FJ09GS302 family of devices provides
high-speed successive approximation, Analog-to-Digital
conversions to support applications such as AC-to-DC
and DC-to-DC Power Converters.
19.1 Features Overview
The ADC module comprises the following features:
• 10-bit resolution
• Unipolar inputs
• One Successive Approximation Register (SAR)
• Up to eight 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
• 2 Msps conversion rate at 3.3V
• 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 small conversion delay reduces the
“phase lag” between measurement and control system
response.
Up to three inputs may be sampled at a time (two 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 and
EXTREF input signals (not available in
dsPIC33FJ06GS101A/102A devices)
Block diagrams of the ADC module are shown in
Figure 19-1 through Figure 19-5.
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 has one SAR
and only one conversion can be processed at a time,
yielding a conversion rate of 2 Msps or the equivalent of
one 10-bit conversion, in half a microsecond (0.5
µs).
The ADC module supports up to eight 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).
Note 1: This data sheet summarizes the features
of the dsPIC33FJ06GS001/101A/102A/
202A and dsPIC33FJ09GS302 families of
devices. It is not intended to be a
comprehensive reference source. To com-
plement the information in this data sheet,
refer to Section 44. “High-Speed 10-Bit
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.
Note: The dsPIC33FJ06GS101A/102A devices
do not have the internal connection to
EXTREF.