JN5148-001 Jennic LTD, JN5148-001 Datasheet - Page 27

• Manufacturer Part Number: JN5148-001
• Description: 32BIT, MCU, ZIGBEE PRO, 128K RAM, 56QFN
• Manufacturer: Jennic LTD

Specifications of JN5148-001

• No. Of I/o's: 21
• Eeprom Memory Size: 128KB
• Ram Memory Size: 128KB
• Cpu Speed: 32MHz
• No. Of Timers: 3
• No. Of Pwm Channels: 3
• Digital Ic Case Style: QFN
• Core Size: 32bit
• Oscillator Type: External
• Peripherals: ADC, DAC, PWM, Timer
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Jennic
8.1.1 Radio External Components
In order to realise the full performance of the radio it is essential that the reference PCB layout and BOM are carefully
followed. See Appendix B.4.
The radio is powered from a number of internal 1.8V regulators fed from the analogue supply VDD1, in order to
provide good noise isolation between the digital logic of the JN5148 and the analogue blocks. These regulators are
also controlled by the baseband controller and protocol software to minimise power consumption. Decoupling for
internal regulators is required as described in section 2.2.1, Power Supplies
For single ended antennas or connectors, a balun is not required, however a matching network is needed.
The RF matching network requires three external components and the IBIAS pin requires one external component as
shown in schematic in B.4.1. These components are critical and should be placed close to the JN5148 pins and
analogue ground as defined in Table 8: JN5148 Printed Antenna Reference Module Components and PCB Layout
Constraints
8.1.2 . Antenna Diversity
Support is provided for antenna diversity. Antenna diversity is a technique that maximises the performance of an
antenna system. It allows the radio to switch between two antennas that have very low correlation between their
received signals. Typically, this is achieved by spacing two antennas around 0.25 wavelengths apart or by using two
orthogonal polarisations. So, if a packet is transmitted and no acknowledgement is received, the radio system can
switch to the other antenna for the retry, with a different probability of success.
The JN5148 provides an output (ADO) on DIO12 that is asserted on odd numbered retries that can be used to control
an antenna switch; this enables antenna diversity to be implemented easily (see Figure 15 and Figure 16).
Antenna A
Antenna B
A
B
SEL
ADO (DIO[12])
RF Switch: Single-Pole, Double-Throw (SPDT)
SELB
COM
Device RF Port
Figure 15 Simple Antenna Diversity Implementation using External RF Switch
© Jennic 2009
JN-DS-JN5148-001 1v2
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Preliminary