C8051F962-A-GM Silicon Labs, C8051F962-A-GM Datasheet - Page 302

• Manufacturer Part Number: C8051F962-A-GM
• Description: 8-bit Microcontrollers - MCU 128KB, DC-DC, AES DQFN76
• Manufacturer: Silicon Labs

Specifications of C8051F962-A-GM

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 25 MHz
• Program Memory Size: 128 KB
• Data Ram Size: 8448 B
• On-chip Adc: Yes
• Operating Supply Voltage: 2.5 V to 3.3 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: DQFN-76
• Mounting Style: SMD/SMT
• Number Of Programmable I/os: 57
• Number Of Timers: 4

C8051F96x
24.2.5. Automatic Gain Control (Crystal Mode Only) and SmaRTClock Bias Doubling
Automatic Gain Control allows the SmaRTClock oscillator to trim the oscillation amplitude of a crystal in
order to achieve the lowest possible power consumption. Automatic Gain Control automatically detects
when the oscillation amplitude has reached a point where it safe to reduce the drive current, therefore, it
may be enabled during crystal startup. It is recommended to enable Automatic Gain Control in most sys-
tems which use the SmaRTClock oscillator in Crystal Mode. The following are recommended crystal spec-
ifications and operating conditions when Automatic Gain Control is enabled:




When using Automatic Gain Control, it is recommended to perform an oscillation robustness test to ensure
that the chosen crystal will oscillate under the worst case condition to which the system will be exposed.
The worst case condition that should result in the least robust oscillation is at the following system condi-
tions: lowest temperature, highest supply voltage, highest ESR, highest load capacitance, and lowest bias
current (AGC enabled, Bias Double Disabled).
To perform the oscillation robustness test, the SmaRTClock oscillator should be enabled and selected as
the system clock source. Next, the SYSCLK signal should be routed to a port pin configured as a push-pull
digital output. The positive duty cycle of the output clock can be used as an indicator of oscillation robust-
302
ESR < 50 k
Load Capacitance < 10 pF
Supply Voltage < 3.0 V
Temperature > –20 °C
LOADCAP
0000
0001
0010
0011
0100
0101
0110
1000
1001
1010
1011
1100
1101
0111
1110
1111
Table 24.2. SmaRTClock Load Capacitance Settings
Crystal Load Capacitance
10.5 pF
12.5 pF
13.5 pF
11.5 pF
4.0 pF
4.5 pF
5.0 pF
5.5 pF
6.0 pF
6.5 pF
7.0 pF
7.5 pF
8.0 pF
8.5 pF
9.0 pF
9.5 pF
Rev. 0.5
Equivalent Capacitance seen on
XTAL3 and XTAL4
10.0 pF
11.0 pF
12.0 pF
13.0 pF
14.0 pF
15.0 pF
16.0 pF
17.0 pF
18.0 pF
19.0 pF
23.0 pF
25.0 pF
27.0 pF
21.0 pF
9.0 pF
8.0 pF