EM2420-STR Ember, EM2420-STR Datasheet - Page 51

• Manufacturer Part Number: EM2420-STR
• Description: IC RF TXRX ZIGBEE 2.4GHZ 48-QLP
• Manufacturer: Ember

Specifications of EM2420-STR

• Mfg Application Notes: EM2420
• Frequency: 2.4GHz
• Data Rate - Maximum: 250kbps
• Modulation Or Protocol: 802.15.4
• Applications: ZigBee™
• Power - Output: -3dBm
• Sensitivity: -94dBm
• Voltage - Supply: 2.1 V ~ 3.6 V
• Current - Receiving: 19.7mA
• Current - Transmitting: 17.4mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-QLP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Memory Size: -

operation of the crystal. In addition,
loading capacitors (C
crystal are required. The loading capacitor
values
capacitance, C
The total load capacitance seen between
the crystal terminals should equal C
the crystal to oscillate at the specified
frequency.
The parasitic capacitance is constituted by
pin input capacitance and PCB stray
capacitance.
capacitance is typically 2 pF - 5 pF. A
Input / Output Matching
The RF input / output is differential (RF_N
and RF_P). In addition there is a supply
switch output pin (TXRX_SWITCH) that
must have an external DC path to RF_N
and RF_P.
In RX mode the TXRX_SWITCH pin is at
ground and will bias the LNA. In TX mode
the TXRX_SWITCH pin is at supply rail
voltage and will properly bias the internal
PA.
Transmitter Test Modes
C
Ember Part Number: 120-0049-000D
L
=
C
1
381
depend
1
+
XOSC16_Q1
XOSC16_Q1
C
1
L
391
, specified for the crystal.
The
+
on
C
381
parasitic
Table 10. Crystal oscillator component values
the
and C
total
Figure 28. Crystal oscillator circuit
Item
C381
C391
C391
C391
total
391
) for the
parasitic
L
load
EM2420 Datasheet
for
XTAL
XTAL
XTAL
C
27 pF
27 pF
L
= 16 pF
trimming capacitor may be placed across
C
The crystal oscillator circuit is shown in
Figure 28. Typical component values for
different values of C
10.
The
regulated. This means that a high current
is used to start up the oscillations. When
the amplitude builds up, the current is
reduced to what is necessary to maintain
a stable oscillation. This ensures a fast
start-up and keeps the drive level to a
minimum. The ESR of the crystal must be
within the specification in order to ensure
a reliable start-up (see the Electrical
Specifications section).
The RF output and DC bias can be done
using different topologies. Some are
shown in Figure 3 and Figure 4.
Component values are given in Table 2.
Using a differential antenna, no balun is
required.
If a single-ended output is required (for a
single-ended connector or a single ended
antenna), a balun should be used for
optimum performance. The balun can be
realized using discrete inductors and
capacitors, or a LTCC balun can be used.
381
for initial tuning if necessary.
crystal
C381
C381
oscillator
XOSC16_Q2
XOSC16_Q2
L
are given in Table
EM2420
is
Page 51 of 84
amplitude