Datasheet

 2011-2013 Microchip Technology Inc. DS70000657H-page 321
dsPIC33EPXXXGP50X, dsPIC33EPXXXMC20X/50X AND PIC24EPXXXGP/MC20X
23.0 10-BIT/12-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC)
The dsPIC33EPXXXGP50X, dsPIC33EPXXXMC20X/
50X and PIC24EPXXXGP/MC20X devices have one
ADC module. The ADC module supports up to
16 analog input channels.
On ADC1, the AD12B bit (AD1CON1<10>) allows the
ADC module to be configured by the user as either a
10-bit, 4 Sample-and-Hold (S&H) ADC (default
configuration) or a 12-bit, 1 S&H ADC.
23.1 Key Features
23.1.1 10-BIT ADC CONFIGURATION
The 10-bit ADC configuration has the following key
features:
• Successive Approximation (SAR) conversion
• Conversion speeds of up to 1.1 Msps
• Up to 16 analog input pins
• Connections to three internal op amps
• Connections to the Charge Time Measurement Unit
(CTMU) and temperature measurement diode
• Channel selection and triggering can be controlled
by the Peripheral Trigger Generator (PTG)
• External voltage reference input pins
• Simultaneous sampling of:
- Up to four analog input pins
- Three op amp outputs
- Combinations of analog inputs and op amp
outputs
• Automatic Channel Scan mode
• Selectable conversion Trigger source
• Selectable Buffer Fill modes
• Four result alignment options (signed/unsigned,
fractional/integer)
• Operation during CPU Sleep and Idle modes
23.1.2 12-BIT ADC CONFIGURATION
The 12-bit ADC configuration supports all the features
listed above, with the exception of the following:
• In the 12-bit configuration, conversion speeds of
up to 500 ksps are supported
• There is only one S&H amplifier in the 12-bit
configuration; therefore, simultaneous sampling
of multiple channels is not supported.
Depending on the particular device pinout, the ADC
can have up to 16 analog input pins, designated AN0
through AN15. These analog inputs are shared with
op amp inputs and outputs, comparator inputs, and
external voltage references. When op amp/comparator
functionality is enabled, or an external voltage refer-
ence is used, the analog input that shares that pin is no
longer available. The actual number of analog input
pins, op amps and external voltage reference input
configuration depends on the specific device.
A block diagram of the ADC module is shown in
Figure 23-1. Figure 23-2 provides a diagram of the
ADC conversion clock period.
Note 1: This data sheet summarizes the
features of the dsPIC33EPXXXGP50X,
dsPIC33EPXXXMC20X/50X and
PIC24EPXXXGP/MC20X families of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to “Analog-to-Digital
Converter (ADC)” (DS70621) in the
“dsPIC33/PIC24 Family Reference
Manual”, which is available from 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 ADC module needs to be disabled
before modifying the AD12B bit.