EM357-RTR Ember, EM357-RTR Datasheet - Page 46

• 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

6.3.1
The high-frequency RC oscillator (OSCHF) is used as the default system clock source when power is applied to
the core domain. The nominal frequency coming out of reset is 12 MHz and Ember software calibrates this
clock to 12 MHz. Table 6-6 contains the specification for the high frequency RC oscillator.
Most peripherals, excluding the radio peripheral, are fully functional using the OSCHF clock source.
Application software must be aware that peripherals are clocked at different speeds depending on whether
OSCHF or OSC24M is being used. Since the frequency step of OSCHF is 0.3 MHz and the high-frequency crystal
oscillator is used for calibration, the calibrated accuracy of OSCHF is ±150 kHz ±40 ppm. The UART and ADC
peripherals may not be usable due to the lower accuracy of the OSCHF frequency.
6.3.2
The high-frequency crystal oscillator (OSC24M) requires an external 24 MHz crystal with an accuracy of
±40 ppm. Based upon the application’s bill of materials and current consumption requirements, the external
crystal may cover a range of ESR requirements. Table 6-7 contains the specification for the high frequency
crystal oscillator.
The crystal oscillator has a software-programmable bias circuit to minimize current consumption. Ember
software configures the bias circuit for minimum current consumption.
All peripherals including the radio peripheral are fully functional using the OSC24M clock source. Application
software must be aware that peripherals are clocked at different speeds depending on whether OSCHF or
OSC24M is being used.
If the 24 MHz crystal fails, a hardware failover mechanism forces the system to switch back to the high-
frequency RC oscillator as the main clock source, and a non-maskable interrupt (NMI) is signaled to the ARM
Cortex
Parameter
Frequency at reset
Frequency Steps
Duty cycle
Supply dependence
Parameter
Frequency
Accuracy
Duty cycle
Start-up time at max bias
Start up time at optimal bias
Current consumption
TM
-M3 NVIC.
High-Frequency Internal RC Oscillator (OSCHF)
High-Frequency Crystal Oscillator (OSC24M)
Table 6-7. High-Frequency Crystal Oscillator Specification
Table 6-6. High-Frequency RC Oscillator Specification
Test conditions
Change in supply = 0.1 V
Test at supply changes: 1.8 V to 1.7 V
Final
6-8
Test conditions
Min
-40
EM351 / EM357
Min
40
40
6
Typ
200
24
Typ
0.3
12
Max
300
+40
60
1
2
Max
120-035X-000G
20
60
5
Unit
ppm
MHz
ms
ms
μA
%
Unit
MHz
MHz
%
%
®