ATMEGA48A-MMHR Atmel, ATMEGA48A-MMHR Datasheet - Page 196

• Manufacturer Part Number: ATMEGA48A-MMHR
• Description: IC MCU AVR 4K FLASH 28QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA48A-MMHR

• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Speed: 20MHz
• Number Of I /o: 23
• Eeprom Size: 256 x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 512 x 8
• Program Memory Size: 4KB (4K x 8)
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: I²C, SPI, UART/USART
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Examples of UBRRn Settings for Commonly Used Oscillator Frequencies
Note:
8271C–AVR–08/10
Baud
Rate
(bps)
2400
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
230.4k
250k
Max.
(1)
1. UBRRn = 0, Error = 0.0%
UBRRn
25
12
6
3
2
1
1
0
–
–
–
–
62.5 kbps
U2Xn = 0
f
Error
-18.6%
osc
-7.0%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
–
–
= 1.0000 MHz
table. Higher error ratings are acceptable, but the Receiver will have less noise resistance when
the error ratings are high, especially for large serial frames (see
Range” on page
ATmega48A/48PA/88A/88PA/168A/168PA/328/328
UBRRn
51
25
12
8
6
3
2
1
1
0
–
–
U2Xn = 1
125 kbps
Error
-18.6%
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
193). The error values are calculated using the following equation:
UBRRn
47
23
11
7
5
3
2
1
1
0
–
–
115.2 kbps
U2Xn = 0
Error[%]
f
osc
Error
-25.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
= 1.8432 MHz
–
–
=
⎛
⎝
BaudRate
------------------------------------------------- - 1
UBRRn
BaudRate
95
47
23
15
11
230.4 kbps
2
U2Xn = 1
7
5
3
1
0
–
Closest Match
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
–
UBRRn
⎞
⎠
•
51
25
12
100%
8
6
3
2
1
1
0
–
–
U2Xn = 0
125 kbps
”Asynchronous Operational
f
osc
Error
-18.6%
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
= 2.0000 MHz
UBRRn
103
51
25
16
12
8
3
2
6
1
–
0
U2Xn = 1
250 kbps
Error
-3.5%
-7.0%
0.2%
0.2%
0.2%
2.1%
0.2%
8.5%
8.5%
8.5%
0.0%
–
196