C8051F040-TB Silicon Laboratories Inc, C8051F040-TB Datasheet - Page 33

• Manufacturer Part Number: C8051F040-TB
• Description: BOARD PROTOTYPING W/C8051F040
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F040-TB

• Contents: Board
• Processor To Be Evaluated: C8051F04x
• Interface Type: USB
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: C8051F040
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

1.9.
The C8051F040/1/2/3 devices have an on-board 8-bit SAR ADC (ADC2) with an 8-channel input multi-
plexer and programmable gain amplifier. This ADC features a 500 ksps maximum throughput and true 8-
bit performance with an INL of ±1LSB. Eight input pins are available for measurement and can be pro-
grammed as single-ended or differential inputs. The ADC is under full control of the CIP-51 microcontroller
via the Special Function Registers. The ADC2 voltage reference is selected between the analog power
supply (AV+) and an external VREF pin. On C8051F040/2 devices, ADC2 has its own dedicated VREF2
input pin; on C8051F041/3 devices, ADC2 shares the VREFA input pin with the 12/10-bit ADC0. User soft-
ware may put ADC2 into shutdown mode to save power.
A programmable gain amplifier follows the analog multiplexer. The gain stage can be especially useful
when different ADC input channels have widely varied input voltage signals, or when it is necessary to
"zoom in" on a signal with a large dc offset (in differential mode, a DAC could be used to provide the dc off-
set). The PGA gain can be set in software to 0.5, 1, 2, or 4.
A flexible conversion scheduling system allows ADC2 conversions to be initiated by software commands,
timer overflows, or an external input signal. ADC2 conversions may also be synchronized with ADC0 soft-
ware-commanded conversions. Conversion completions are indicated by a status bit and an interrupt (if
enabled), and the resulting 8-bit data word is latched into an SFR upon completion.
AIN2.0
AIN2.1
AIN2.2
AIN2.3
AIN2.4
AIN2.5
AIN2.6
AIN2.7
8-Bit Analog to Digital Converter (C8051F040/1/2/3 Only)
Differential Measurement
Single-ended or
Analog Multiplexer
+
+
+
+
-
-
-
-
AMUX
8-to-1
Figure 1.13. 8-Bit ADC Diagram
Programmable Gain
X
Amplifier
External VREF
Configuration, Control, and Data Registers
+
-
AV+
AV+
Pin
Rev. 1.5
C8051F040/1/2/3/4/5/6/7
ADC
VREF
8-Bit
SAR
Start Conversion
8
Compare Logic
Window
Write to AD2BUSY
Timer 3 Overflow
CNVSTR2 Input
Timer 2 Overflow
Write to AD0BUSY
(synchronized with
ADC0)
Conversion
Complete
ADC Data
Interrupt
Register
Compare
Interrupt
Window
33