EFM32LG995F256 Energy Micro, EFM32LG995F256 Datasheet - Page 22

• Manufacturer Part Number: EFM32LG995F256
• Description: ARM Microcontrollers - MCU 256KB FL 32KB RAM
• Manufacturer: Energy Micro

Specifications of EFM32LG995F256

• Rohs: yes
• Core: ARM Cortex M3
• Processor Series: Leopard Gecko (LG)
• Data Bus Width: 32 bit
• Maximum Clock Frequency: 48 MHz
• Program Memory Size: 256 KB
• Data Ram Size: 32 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 1.85 V to 3.8 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: BGA-120
• Mounting Style: SMD/SMT
• A/d Bit Size: 12 bit
• Interface Type: I2C, SPI, USB, UART
• Number Of Programmable I/os: 93
• Program Memory Type: Flash

3.9 Oscillators
3.9.1 LFXO
2012-09-11 - EFM32LG995FXX - d0124_Rev1.00
Table 3.9. LFXO
For safe startup of a given crystal, the load capacitance should be larger than the value indicated in
Figure 3.7 (p. 22) and in Table 3.10 (p. 23) for a given LFXOBOOST setting. The minimum
supported load capacitance depends on the crystal shunt capacitance, C
vendors’ datasheet.
Figure 3.7. Minimum Load Capacitance (C
Symbol
f
ESR
C
DC
I
t
LFXO
LFXO
LFXO
LFXOL
LFXO
LFXO
Parameter
Supported nominal crystal
frequency
Supported crystal equiv-
alent series resistance
(ESR)
Supported crystal external
load range
Duty cycle
Current consumption for
core and buffer after start-
up.
Start- up time.
20
14
18
16
12
10
Preliminary
8
6
4
2
0.6
LFXOBOOST= 0,REDLFXOBOOST= 1
LFXOBOOST= 0,REDLFXOBOOST= 0
LFXOBOOST= 1,REDLFXOBOOST= 1
LFXOBOOST= 1,REDLFXOBOOST= 0
Condition
ESR=30 kOhm, C
LFXOBOOST in CMU_CTRL
is 1
ESR=30 kOhm, C
40% - 60% duty cycle has
been reached, LFXOBOOST
in CMU_CTRL is 1
0.8
1.0
LFXOL
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22
1.2
C0 [ pF]
) Requirement For Safe Crystal Startup
L
L
=10 pF,
=10 pF,
1.4
1.6
Min
1.8
2.0
48
5
0
, which is specified in crystal
Typ
32.768
www.energymicro.com
190
400
30
50
Max
53.5 %
120 kOhm
25 pF
Unit
kHz
nA
ms