Datasheet
Table Of Contents
- Devices Included in this Data Sheet:
- Microcontroller Core Features:
- Pin Diagram
- Peripheral Features:
- Pin Diagrams
- Table of Contents
- 1.0 Device Overview 5
- 2.0 Memory Organization 11
- 3.0 I/O Ports 29
- 4.0 Data EEPROM and FLASH Program Memory 41
- 5.0 Timer0 Module 47
- 6.0 Timer1 Module 51
- 7.0 Timer2 Module 55
- 8.0 Capture/Compare/PWM Modules 57
- 9.0 Master Synchronous Serial Port (MSSP) Module 65
- 10.0 Addressable Universal Synchronous Asynchronous Receiver Transmitter (USART) 95
- 11.0 Analog-to-Digital Converter (A/D) Module 111
- 12.0 Special Features of the CPU 119
- 13.0 Instruction Set Summary 135
- 14.0 Development Support 143
- 15.0 Electrical Characteristics 149
- 16.0 DC and AC Characteristics Graphs and Tables 177
- 17.0 Packaging Information 189
- Most Current Data Sheet
- Errata
- Customer Notification System
- 1.0 Device Overview
- 2.0 Memory Organization
- 3.0 I/O Ports
- 4.0 Data EEPROM and Flash Program Memory
- 4.1 EECON1 and EECON2 Registers
- 4.2 Reading the EEPROM Data Memory
- 4.3 Writing to the EEPROM Data Memory
- 4.4 Reading the FLASH Program Memory
- 4.5 Writing to the FLASH Program Memory
- 4.6 Write Verify
- 4.7 Protection Against Spurious Writes
- 4.8 Operation While Code Protected
- 4.9 FLASH Program Memory Write Protection
- 5.0 Timer0 Module
- 6.0 Timer1 Module
- 6.1 Timer1 Operation in Timer Mode
- 6.2 Timer1 Counter Operation
- 6.3 Timer1 Operation in Synchronized Counter Mode
- 6.4 Timer1 Operation in Asynchronous Counter Mode
- 6.5 Timer1 Oscillator
- 6.6 Resetting Timer1 using a CCP Trigger Output
- 6.7 Resetting of Timer1 Register Pair (TMR1H, TMR1L)
- 6.8 Timer1 Prescaler
- 7.0 Timer2 Module
- 8.0 Capture/Compare/PWM Modules
- 9.0 Master Synchronous Serial Port (MSSP) Module
- 9.1 SPI Mode
- 9.2 MSSP I2C Operation
- 9.2.1 SLAVE Mode
- 9.2.2 General Call Address Support
- 9.2.3 Sleep Operation
- 9.2.4 Effects of a Reset
- 9.2.5 Master Mode
- 9.2.6 Multi-master Mode
- 9.2.7 I2C Master Mode Support
- 9.2.8 Baud Rate Generator
- 9.2.9 I2C Master Mode Start Condition Timing
- 9.2.10 I2C Master Mode Repeated Start Condition Timing
- 9.2.11 I2C Master Mode Transmission
- 9.2.12 I2C Master Mode Reception
- 9.2.13 Acknowledge Sequence Timing
- 9.2.14 Stop Condition Timing
- 9.2.15 Clock Arbitration
- 9.2.16 Sleep Operation
- 9.2.17 Effects of a Reset
- 9.2.18 Multi -Master Communication, Bus Collision, And Bus Arbitration
- 9.3 Connection Considerations for I2C Bus
- 10.0 Addressable Universal Synchronous Asynchronous Receiver Transmitter (USART)
- 11.0 Analog-to-Digital Converter (A/D) Module
- 12.0 Special Features of the CPU
- 12.1 Configuration Bits
- 12.2 Oscillator Configurations
- 12.3 RESET
- 12.4 Power-On Reset (POR)
- 12.5 Power-up Timer (PWRT)
- 12.6 Oscillator Start-up Timer (OST)
- 12.7 Brown-out Reset (BOR)
- 12.8 Time-out Sequence
- 12.9 Power Control/Status Register (PCON)
- 12.10 Interrupts
- 12.11 Context Saving During Interrupts
- 12.12 Watchdog Timer (WDT)
- 12.13 Power-down Mode (SLEEP)
- 12.14 In-Circuit Debugger
- 12.15 Program Verification/Code Protection
- 12.16 ID Locations
- 12.17 In-Circuit Serial Programming
- 12.18 Low Voltage ICSP Programming
- 13.0 Instruction Set Summary
- 14.0 Development Support
- 14.1 MPLAB Integrated Development Environment Software
- 14.2 MPASM Assembler
- 14.3 MPLAB C17 and MPLAB C18 C Compilers
- 14.4 MPLINK Object Linker/ MPLIB Object Librarian
- 14.5 MPLAB SIM Software Simulator
- 14.6 MPLAB ICE High Performance Universal In-Circuit Emulator with MPLAB IDE
- 14.7 ICEPIC In-Circuit Emulator
- 14.8 MPLAB ICD In-Circuit Debugger
- 14.9 PRO MATE II Universal Device Programmer
- 14.10 PICSTART Plus Entry Level Development Programmer
- 14.11 PICDEM 1 Low Cost PIC MCU Demonstration Board
- 14.12 PICDEM 2 Low Cost PIC16CXX Demonstration Board
- 14.13 PICDEM 3 Low Cost PIC16CXXX Demonstration Board
- 14.14 PICDEM 17 Demonstration Board
- 14.15 KeeLoq Evaluation and Programming Tools
- 15.0 Electrical Characteristics
- 15.1 DC Characteristics: PIC16F873/874/876/877-04 (Commercial, Industrial) PIC16F873/874/876/877-20 (Commercial, Industrial) PIC16LF873/874/876/877-04 (Commercial, Industrial)
- 15.2 DC Characteristics: PIC16F873/874/876/877-04 (Commercial, Industrial) PIC16F873/874/876/877-20 (Commercial, Industrial) PIC16LF873/874/876/877-04 (Commercial, Industrial)
- 15.3 DC Characteristics: PIC16F873/874/876/877-04 (Extended) PIC16F873/ 874/ 876/ 877-10 (Extended)
- 15.4 DC Characteristics: PIC16F873/874/876/877-04 (Extended) PIC16F873/874/876/877-10 (Extended)
- 15.5 Timing Parameter Symbology
- 16.0 DC and AC Characteristics Graphs and Tables
- 17.0 Packaging Information
- 17.1 Package Marking Information
- Package Marking Information (Cont’d)
- 28-Lead Skinny Plastic Dual In-line (SP) – 300 mil (PDIP)
- 28-Lead Plastic Small Outline (SO) – Wide, 300 mil (SOIC)
- 40-Lead Plastic Dual In-line (P) – 600 mil (PDIP)
- 44-Lead Plastic Thin Quad Flatpack (PT) 10x10x1 mm Body, 1.0/0.10 mm Lead Form (TQFP)
- 44-Lead Plastic Metric Quad Flatpack (PQ) 10x10x2 mm Body, 1.6/0.15 mm Lead Form (MQFP)
- 44-Lead Plastic Leaded Chip Carrier (L) – Square (PLCC)
- Appendix A: Revision History
- Appendix B: Device Differences
- Appendix C: Conversion CONSIDERATIONS
- Index
- A
- Acquisition Requirements 114
- ADCON0 Register 111
- ADCON1 Register 112
- ADIF bit 112
- Analog Input Model Block Diagram 114
- Analog Port Pins 7, 8, 9, 36, 38
- Associated Registers and Bits 117
- Block Diagram 113
- Calculating Acquisition Time 114
- Configuring Analog Port Pins 115
- Configuring the Interrupt 113
- Configuring the Module 113
- Conversion Clock 115
- Conversions 116
- Delays 114
- Effects of a RESET 117
- GO/DONE bit 112
- Internal Sampling Switch (Rss) Impedence 114
- Operation During SLEEP 117
- Result Registers 116
- Sampling Requirements 114
- Source Impedence 114
- Time Delays 114
- AN552 (Implementing Wake-up on Key Strokes Using PIC16CXXX) 31
- AN556 (Implementing a Table Read) 26
- AN578 (Use of the SSP Module in the I2C Multi-Master Environment) 73
- PIC16F873/PIC16F876 Block Diagram 5
- PIC16F874/PIC16F877 Block Diagram 6
- MPASM Assembler 143
- A/D 113
- A/D Converter 113
- Analog Input Model 114
- Baud Rate Generator 79
- Capture Mode 59
- Compare Mode 60
- I2C Master Mode 78
- I2C Module 73
- I2C Slave Mode 73
- Interrupt Logic 129
- PIC16F873/PIC16F876 5
- PIC16F874/PIC16F877 6
- PORTA
- PORTB
- PORTC
- PORTD 35
- PORTD and PORTE (Parallel Slave Port) 38
- PORTE 36
- PWM Mode 61
- RESET Circuit 123
- SSP (I2C Mode) 73
- SSP (SPI Mode) 69
- Timer0/WDT Prescaler 47
- Timer1 52
- Timer2 55
- USART Asynchronous Receive 101
- USART Asynchronous Receive (9-bit Mode) 103
- USART Transmit 99
- Watchdog Timer 131
- BOR Status (BOR Bit) 25
- Associated Registers
- Capture Mode 59
- CCP Timer Resources 57
- CCP1
- CCP2
- Compare
- Compare Mode 60
- Interaction of Two CCP Modules (table) 57
- PWM Mode 61
- Special Event Trigger and A/D Conversions 60
- Call of a Subroutine in Page 1 from Page 0 26
- EEPROM Data Read 43
- EEPROM Data Write 43
- FLASH Program Read 44
- FLASH Program Write 45
- Indirect Addressing 27
- Initializing PORTA 29
- Saving STATUS, W and PCLATH Registers 130
- Data EEPROM and FLASH Program Memory 45
- Associated Registers 46
- Code Protection 45
- Reading 43
- Special Functions Registers 41
- Spurious Write Protection 45
- Write Verify 45
- Writing to 43
- Bank Select (RP1:RP0 Bits) 12, 18
- General Purpose Registers 12
- Register File Map 13, 14
- Special Function Registers 15
- Commercial and Industrial 152– 156
- Extended 157– 160
- Associated Registers 46
- Code Protection 45
- Configuration Bits and Read/Write State 46
- Reading 44
- Special Function Registers 41
- Spurious Write Protection 45
- Write Protection 46
- Write Verify 45
- Writing to 44
- Connection Considerations 94
- Sample Device Configuration 94
- Acknowledge Sequence Timing 86
- Addressing 74
- Associated Registers 77
- Baud Rate Generator 79
- Block Diagram 78
- BRG Block Diagram 79
- BRG Reset due to SDA Collision 91
- BRG Timing 80
- Bus Arbitration 89
- Bus Collision 89
- Bus Collision Timing 89
- Clock Arbitration 88
- Clock Arbitration Timing (Master Transmit) 88
- Conditions to not give ACK Pulse 74
- General Call Address Support 76
- Master Mode 78
- Master Mode 7-bit Reception Timing 85
- Master Mode Block Diagram 78
- Master Mode Operation 79
- Master Mode START Condition 80
- Master Mode Transmission 82
- Master Mode Transmit Sequence 79
- Multi-Master Communication 89
- Multi-master Mode 78
- Operation 73
- Repeat START Condition Timing 81
- Slave Mode 74
- Slave Reception 74
- Slave Transmission 75
- SSPBUF 73
- STOP Condition Receive or Transmit Timing 87
- STOP Condition Timing 87
- Waveforms for 7-bit Reception 75
- Waveforms for 7-bit Transmission 76
- FSR Register 12
- ADDLW 137
- ADDWF 137
- ANDLW 137
- ANDWF 137
- BCF 137
- BSF 137
- BTFSC 137
- BTFSS 137
- CALL 138
- CLRF 138
- CLRW 138
- CLRWDT 138
- COMF 138
- DECF 138
- DECFSZ 139
- GOTO 139
- INCF 139
- INCFSZ 139
- IORLW 139
- IORWF 139
- MOVF 140
- MOVLW 140
- MOVWF 140
- NOP 140
- RETFIE 140
- RETLW 140
- RETURN 141
- RLF 141
- RRF 141
- SLEEP 141
- SUBLW 141
- SUBWF 141
- SWAPF 142
- XORLW 142
- XORWF 142
- Summary Table 136
- GIE Bit 20
- INTE Bit 20
- INTF Bit 20
- PEIE Bit 20
- RBIE Bit 20
- RBIF Bit 20, 31
- T0IE Bit 20
- T0IF Bit 20
- Block Diagram 129
- Interrupt-on-Change (RB7:RB4 ) 31
- RB0/INT Pin, External 7, 8, 130
- TMR0 Overflow 130
- USART Receive/Transmit Complete 95
- Bus Collision Interrupt 24
- Synchronous Serial Port Interrupt 22
- Global Interrupt Enable (GIE Bit) 20, 129
- Interrupt-on-Change (RB7:RB4) Enable (RBIE Bit) 130
- Interrupt-on-Change (RB7:RB4) Enable (RBIE Bit) 20
- Peripheral Interrupt Enable (PEIE Bit) 20
- RB0/INT Enable (INTE Bit) 20
- TMR0 Overflow Enable (T0IE Bit) 20
- Interrupt-on-Change (RB7:RB4) Flag (RBIF Bit) 130
- Interrupt-on-Change (RB7:RB4) Flag (RBIF Bit) 20, 31
- RB0/INT Flag (INTF Bit) 20
- TMR0 Overflow Flag (T0IF Bit) 20, 130
- MCLR Reset, Normal Operation 123, 125, 126
- MCLR Reset, SLEEP 123, 125, 126
- Data Memory 12
- Program Memory 11
- INTEDG Bit 19
- PS2:PS0 Bits 19
- PSA Bit 19
- T0CS Bit 19
- T0SE Bit 19
- HS 121, 124
- LP 121, 124
- RC 121, 122, 124
- XT 121, 124
- Capacitor Selection 122
- Crystal and Ceramic Resonators 121
- RC 122
- Associated Registers 39
- Block Diagram 38
- RE0/RD/AN5 Pin 9, 36, 38
- RE1/WR/AN6 Pin 9, 36, 38
- RE2/CS/AN7 Pin 9, 36, 38
- Read Waveforms 39
- Select (PSPMODE Bit) 35, 36, 37, 38
- Write Waveforms 39
- BOR Bit 25
- POR Bit 25
- PIC16F873/PIC16F876 7
- PIC16F874/PIC16F877 8
- Analog Port Pins 7, 8
- Associated Registers 30
- Block Diagram
- Initialization 29
- PORTA Register 15, 29
- RA3
- RA4/T0CKI Pin 7, 8
- RA5/SS/AN4 Pin 7, 8
- TRISA Register 29
- Associated Registers 32
- Block Diagram
- PORTB Register 15, 31
- RB0/INT Edge Select (INTEDG Bit) 19
- RB0/INT Pin, External 7, 8, 130
- RB7:RB4 Interrupt on Change 130
- RB7:RB4 Interrupt on Change Enable (RBIE Bit) 130
- RB7:RB4 Interrupt on Change Flag (RBIF Bit) 130
- RB7:RB4 Interrupt-on-Change Enable (RBIE Bit) 20
- RB7:RB4 Interrupt-on-Change Flag (RBIF Bit) 20, 31
- TRISB Register 17, 31
- Associated Registers 34
- Block Diagrams
- PORTC Register 15, 33
- RC0/T1OSO/T1CKI Pin 7, 9
- RC1/T1OSI/CCP2 Pin 7, 9
- RC2/CCP1 Pin 7, 9
- RC3/SCK/SCL Pin 7, 9
- RC4/SDI/SDA Pin 7, 9
- RC5/SDO Pin 7, 9
- RC6/TX/CK Pin 7, 9, 96
- RC7/RX/DT Pin 7, 9, 96, 97
- TRISC Register 33, 95
- Associated Registers 35
- Block Diagram 35
- Parallel Slave Port (PSP) Function 35
- PORTD Register 15, 35
- TRISD Register 35
- Analog Port Pins 9, 36, 38
- Associated Registers 36
- Block Diagram 36
- Input Buffer Full Status (IBF Bit) 37
- Input Buffer Overflow (IBOV Bit) 37
- Output Buffer Full Status (OBF Bit) 37
- PORTE Register 15, 36
- PSP Mode Select (PSPMODE Bit) 35, 36, 37, 38
- RE0/RD/AN5 Pin 9, 36, 38
- RE1/WR/AN6 Pin 9, 36, 38
- RE2/CS/AN7 Pin 9, 36, 38
- TRISE Register 36
- Assignment (PSA Bit) 19
- Rate Select (PS2:PS0 Bits) 19
- Oscillator Start-up Timer (OST) 119, 124
- POR Status (POR Bit) 25
- Power Control (PCON) Register 124
- Power-down (PD Bit) 18, 123
- Power-up Timer (PWRT) 119, 124
- Time-out (TO Bit) 18, 123
- Time-out Sequence on Power-up 127, 128
- Assignment (PSA Bit) 19
- Rate Select (PS2:PS0 Bits) 19
- RESET Conditions 125
- Interrupt Vector 11
- Paging 11, 26
- Program Memory Map 11
- RESET Vector 11
- ADDEN Bit 96
- CREN Bit 96
- FERR Bit 96
- OERR Bit 96
- RX9 Bit 96
- RX9D Bit 96
- SPEN Bit 95, 96
- SREN Bit 96
- ADCON0 (A/D Control 0) 111
- ADCON1 (A/D Control 1) 112
- CCP1CON (CCP Control 1) 58
- EECON2 41
- FSR 27
- INTCON 20
- OPTION_REG 19, 48
- PCON (Power Control) 25
- PIE1 (Peripheral Interrupt Enable 1) 21
- PIE2 (Peripheral Interrupt Enable 2) 23
- PIR1 (Peripheral Interrupt Request 1) 22
- PIR2 (Peripheral Interrupt Request 2) 24
- RCSTA (Receive Status and Control) 96
- Special Function, Summary 15
- SSPCON2 (Sync Serial Port Control 2) 68
- STATUS 18
- T1CON (Timer1 Control) 51
- T2CON (Timer 2 Control)
- TRISE 37
- TXSTA (Transmit Status and Control) 95
- Block Diagram 123
- MCLR Reset. See MCLR
- Brown-out Reset (BOR). See Brown-out Reset (BOR)
- Power-on Reset (POR). See Power-on Reset (POR)
- RESET Conditions for PCON Register 125
- RESET Conditions for Program Counter 125
- RESET Conditions for STATUS Register 125
- WDT Reset. See Watchdog Timer (WDT)
- Data EEPROM and FLASH Program Memory 41
- Master Mode 70
- Master Mode Timing 70
- Serial Clock 69
- Serial Data In 69
- Serial Data Out 69
- Serial Peripheral Interface (SPI) 65
- Slave Mode Timing 71
- Slave Mode Timing Diagram 71
- Slave Select 69
- SPI Clock 70
- SPI Mode 69
- Associated Registers 72
- Slave Mode 71
- Block Diagram (SPI Mode) 69
- RA5/SS/AN4 Pin 7, 8
- RC3/SCK/SCL Pin 7, 9
- RC4/SDI/SDA Pin 7, 9
- RC5/SDO Pin 7, 9
- SPI Mode 69
- SSPADD 73, 74
- SSPBUF 70, 73
- SSPCON2 68
- SSPSR 70, 74
- SSPSTAT 73
- SSP I2C Operation 73
- SPI Master Mode 70
- SPI Slave Mode 71
- SSPCON1 Register 73
- Overflows 26
- Underflow 26
- C Bit 18
- DC Bit 18
- IRP Bit 18
- PD Bit 18, 123
- RP1:RP0 Bits 18
- TO Bit 18, 123
- Z Bit 18
- Associated Registers 49
- Clock Source Edge Select (T0SE Bit) 19
- Clock Source Select (T0CS Bit) 19
- External Clock 48
- Interrupt 47
- Overflow Enable (T0IE Bit) 20
- Overflow Flag (T0IF Bit) 20, 130
- Overflow Interrupt 130
- Prescaler 48
- RA4/T0CKI Pin, External Clock 7, 8
- T0CKI 48
- WDT Prescaler Block Diagram 47
- Associated Registers 54
- Asynchronous Counter Mode 53
- Block Diagram 52
- Counter Operation 52
- Operation in Timer Mode 52
- Oscillator 53
- Prescaler 54
- RC0/T1OSO/T1CKI Pin 7, 9
- RC1/T1OSI/CCP2 Pin 7, 9
- Resetting of Timer1 Registers 54
- Resetting Timer1 using a CCP Trigger Output 53
- Synchronized Counter Mode 52
- T1CON 51
- T1CON Register 51
- TMR1H 53
- TMR1L 53
- Associated Registers 56
- Block Diagram 55
- Output 56
- Postscaler 55
- Prescaler 55
- T2CON 55
- A/D Conversion 175
- Acknowledge Sequence Timing 86
- Baud Rate Generator with Clock Arbitration 80
- BRG Reset Due to SDA Collision 91
- Brown-out Reset 164
- Bus Collision
- Bus Collision During a Repeated START Condition (Case 1) 92
- Bus Collision During a Repeated START Condition (Case2) 92
- Bus Collision During a START Condition (SCL = 0) 91
- Bus Collision During a STOP Condition 93
- Bus Collision for Transmit and Acknowledge 89
- Capture/Compare/PWM 166
- CLKOUT and I/O 163
- I2C Bus Data 171
- I2C Bus START/STOP bits 170
- I2C Master Mode First START Bit Timing 80
- I2C Master Mode Reception Timing 85
- I2C Master Mode Transmission Timing 83
- Master Mode Transmit Clock Arbitration 88
- Power-up Timer 164
- Repeat START Condition 81
- RESET 164
- SPI Master Mode 70
- SPI Slave Mode (CKE = 1) 71
- SPI Slave Mode Timing (CKE = 0) 71
- Start-up Timer 164
- STOP Condition Receive or Transmit 87
- Time-out Sequence on Power-up 127, 128
- Timer0 165
- Timer1 165
- USART Asynchronous Master Transmission 100
- USART Asynchronous Reception 102
- USART Synchronous Receive 173
- USART Synchronous Reception 108
- USART Synchronous Transmission 106, 173
- USART, Asynchronous Reception 104
- Wake-up from SLEEP via Interrupt 133
- Watchdog Timer 164
- IBF Bit 37
- IBOV Bit 37
- OBF Bit 37
- PSPMODE Bit 35, 36, 37, 38
- BRGH Bit 95
- CSRC Bit 95
- SYNC Bit 95
- TRMT Bit 95
- TX9 Bit 95
- TX9D Bit 95
- TXEN Bit 95
- Address Detect Enable (ADDEN Bit) 96
- Asynchronous Mode 99
- Asynchronous Receive 101
- Asynchronous Receive (9-bit Mode) 103
- Asynchronous Receive with Address Detect. SeeAsynchronous Receive (9-bit Mode).
- Asynchronous Reception 102
- Asynchronous Transmitter 99
- Baud Rate Generator (BRG) 97
- Clock Source Select (CSRC Bit) 95
- Continuous Receive Enable (CREN Bit) 96
- Framing Error (FERR Bit) 96
- Mode Select (SYNC Bit) 95
- Overrun Error (OERR Bit) 96
- RC6/TX/CK Pin 7, 9
- RC7/RX/DT Pin 7, 9
- RCSTA Register 96
- Receive Data, 9th bit (RX9D Bit) 96
- Receive Enable, 9-bit (RX9 Bit) 96
- Serial Port Enable (SPEN Bit) 95, 96
- Single Receive Enable (SREN Bit) 96
- Synchronous Master Mode 105
- Synchronous Master Reception 107
- Synchronous Master Transmission 105
- Synchronous Slave Mode 108
- Synchronous Slave Reception 109
- Synchronous Slave Transmit 108
- Transmit Block Diagram 99
- Transmit Data, 9th Bit (TX9D) 95
- Transmit Enable (TXEN Bit) 95
- Transmit Enable, Nine-bit (TX9 Bit) 95
- Transmit Shift Register Status (TRMT Bit) 95
- TXSTA Register 95
- Interrupts 125, 126
- MCLR Reset 126
- Timing Diagram 133
- WDT Reset 126
- Block Diagram 131
- Enable (WDTE Bit) 131
- Postscaler. See Postscaler, WDT
- Programming Considerations 131
- RC Oscillator 131
- Time-out Period 131
- WDT Reset, Normal Operation 123, 125, 126
- WDT Reset, SLEEP 123, 125, 126
- Data EEPROM and FLASH Program Memory 45
- On-Line Support
- Reader Response
- PIC16F87X Product Identification System
- To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
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PIC16F87X
DS30292D-page 114 1998-2013 Microchip Technology Inc.
11.1 A/D Acquisition Requirements
For the A/D converter to meet its specified accuracy,
the charge holding capacitor (C
HOLD) must be allowed
to fully charge to the input channel voltage level. The
analog input model is shown in Figure 11-2. The source
impedance (R
S) and the internal sampling switch (RSS)
impedance directly affect the time required to charge
the capacitor CHOLD. The sampling switch (RSS)
impedance varies over the device voltage (V
DD), see
Figure 11-2. The maximum recommended imped-
ance for analog sources is 10 k. As the impedance
is decreased, the acquisition time may be decreased.
After the analog input channel is selected (changed),
this acquisition must be done before the conversion
can be started.
To calculate the minimum acquisition time,
Equation 11-1 may be used. This equation assumes
that 1/2 LSb error is used (1024 steps for the A/D). The
1/2 LSb error is the maximum error allowed for the A/D
to meet its specified resolution.
To calculate the minimum acquisition time, T
ACQ, see
the PIC
®
MCU Mid-Range Reference Manual
(DS33023).
EQUATION 11-1: ACQUISITION TIME
FIGURE 11-2: ANALOG INPUT MODEL
TACQ
TC
TACQ
=
=
=
=
=
=
=
=
Amplifier Settling Time +
Hold Capacitor Charging Time +
Temperature Coefficient
T
AMP + TC + TCOFF
2s + TC + [(Temperature -25°C)(0.05s/°C)]
C
HOLD (RIC + RSS + RS) In(1/2047)
- 120pF (1k + 7k + 10k) In(0.0004885)
16.47s
2s + 16.47s + [(50°C -25C)(0.05s/C)
19.72s
Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out.
2: The charge holding capacitor (C
HOLD) is not discharged after each conversion.
3: The maximum recommended impedance for analog sources is 10 k. This is required to meet the pin leak-
age specification.
4: After a conversion has completed, a 2.0T
AD delay must complete before acquisition can begin again.
During this time, the holding capacitor is not connected to the selected A/D input channel.
CPIN
VA
R
S
ANx
5 pF
V
DD
VT = 0.6V
V
T = 0.6V
I
LEAKAGE
RIC 1k
Sampling
Switch
SS
R
SS
CHOLD
= DAC capacitance
V
SS
6V
Sampling Switch
5V
4V
3V
2V
567891011
(k)
VDD
= 120 pF
± 500 nA
Legend CPIN
VT
I LEAKAGE
RIC
SS
C
HOLD
= input capacitance
= threshold voltage
= leakage current at the pin due to
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
various junctions