EM357-RTR Ember, EM357-RTR Datasheet - Page 48

• Manufacturer Part Number: EM357-RTR
• Description: IC RF TXRX ZIGBEE 192KB 48QFN
• Manufacturer: Ember

Specifications of EM357-RTR

• Frequency: 2.4GHz
• Data Rate - Maximum: 250kbps
• Modulation Or Protocol: 802.15.4 Zigbee
• Applications: General Purpose
• Power - Output: 5dBm
• Sensitivity: -100dBm
• Voltage - Supply: 2.1 V ~ 3.6 V
• Current - Receiving: 26mA
• Current - Transmitting: 31mA
• Data Interface: PCB, Surface Mount
• Memory Size: 192kB Flash, 12kB RAM
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 636-1011-2

Table 6-9 contains the specification for the low frequency crystal oscillator.
6.3.5
The EM35x has two switching mechanisms for the main system clock, providing four clock modes. Table 6-10
shows these clock modes and how they affect the internal clocks.
The register bit OSC24M_CTRL_OSC24M_SEL in the OSC24M_CTRL register switches between the high-
frequency RC oscillator (OSCHF) and the high-frequency crystal oscillator (OSC24M) as the main system clock
(SYSCLK). The peripheral clock (PCLK) is always half the frequency of SYSCLK.
The register bit CPU_CLKSEL_FIELD in the CPU_CLKSEL register switches between PCLK and SYSCLK to produce
the ARM
higher PCLK frequency, 24 MHz, to give higher processing performance for all applications and improved duty
cycling for applications using sleep modes.
In addition to these modes, further automatic control is invoked by hardware when flash programming is
enabled. To ensure accuracy of the flash controller’s timers, the FCLK frequency is forced to 12 MHz during
flash programming and erase operations.
OSC24M_CTRL_
Parameter
Frequency
Accuracy
Load capacitance OSC32A
Load capacitance OSC32B
Crystal ESR
Start-up time
Current consumption
OSC24M_SEL
1 (OSC24M)
1 (OSC24M)
0 (OSCHF)
0 (OSCHF)
®
Clock Switching
Cortex
TM
-M3 CPU clock (FCLK). The default and preferred mode of operation is to run the CPU at the
CPU_CLKSEL_FI
0 (Normal CPU)
0 (Normal CPU)
1 (Fast CPU)
1 (Fast CPU)
Table 6-9. Low-Frequency Crystal Oscillator Specification
ELD
Test conditions
Initial, temperature, and
ageing
At 25°C, VDD_PADS=3.0 V
Table 6-10. System Clock Modes
SYSCLK
12 MHz
12 MHz
24 MHz
24 MHz
Final
6-10
12 MHz
12 MHz
PCLK
6 MHz
6 MHz
Flash Program/Erase
-100
Min
12 MHz
12 MHz
24 MHz
Inactive
6 MHz
32.768
EM351 / EM357
Typ
27
18
FCLK
Flash Program/Erase
+100
Max
100
0.5
2
12 MHz
12 MHz
12 MHz
12 MHz
Active
120-035X-000G
Unit
ppm
kHz
kΩ
pF
pF
μA
s