MICRF219AAYQS TR Micrel Inc, MICRF219AAYQS TR Datasheet - Page 12

• Manufacturer Part Number: MICRF219AAYQS TR
• Description: IC RECEIVER QWIKRADIO 16QSOP
• Manufacturer: Micrel Inc
• Series: -r

Specifications of MICRF219AAYQS TR

• Frequency: 300MHz ~ 450MHz
• Sensitivity: -112.5dBm
• Data Rate - Maximum: -
• Modulation Or Protocol: ASK, OOK
• Applications: General Purpose
• Current - Receiving: 4.3mA
• Data Interface: PCB, Surface Mount
• Memory Size: -
• Antenna Connector: PCB, Surface Mount
• Features: RSSI Equipped
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 16-SSOP (0.154", 3.90mm Width)
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 576-3892-2; MICRF219AAYQSTR

Micrel, Inc.
Reference Oscillator
The reference oscillator in the MICRF219A (Figure 5)
uses a basic Pierce crystal oscillator configuration with
MOS transconductor. Though the MICRF219A has built-
in load capacitors for the crystal oscillator, the external
load capacitors are still required for tuning it to the right
frequency. RO1 and RO2 are external pins of the
MICRF219A to connect the crystal to the reference
oscillator.
Reference oscillator crystal frequency can be calculated
using Equation 3. For example, if f
= 13.52313MHz. Table 4 lists the values of reference
frequencies at different popular RF frequencies. To
operate the MICRF219A with minimum offset, use
proper loading capacitance recommended by the crystal
manufacturer.
*Empirically derived, slightly different from Equation 3.
Auto-Polling
The MICRF219A can be programmed into an auto-
polling mode by setting register bit D[15] to 1, where it
monitors if there is a valid incoming RF signal while
holding DO low. In this mode, the chip goes between
sleep state and polling state. In sleep state, only a low
power sleep clock is on, resulting in very low current
consumption of 13μA typical. The sleep time is
programmable from 10ms to 1.28s. In a polling state,
every block in the MICRF219A is on, and the chip looks
for signal with bit durations greater than a user-
programmed value.
July 2011
RF Input Frequency (MHz)
Table 4. Reference Frequency Examples
Figure 5. Reference Oscillator Circuit
433.92
315.0
390.0
418.0
This operation is subsequently
Reference Frequency (MHz)
RF
= 433.92MHz, f
13.52313*
12.15446
13.02708
9.81713*
REF
12
called “bit checking” in this datasheet. A “valid bit” is a
mark or space with duration that is longer than the bit
check window.
duration that is shorter than the bit check window. The
user can set different bit check window time to suit a
particular signal by programming register bits D[11:9] as
listed in the register programming section. The number
of consecutive valid bits before releasing DO and exiting
polling mode can also be set by register bits D[8:7].
During the bit checking operation, DO is held low while
the bit checker examines the pulse widths at the node
labeled DO’ in Figure 1. If there is no signal present and
DO’ randomly chatters, the MICRF219A returns to sleep
after seeing 4 consecutive bad bits.
Note that since DO’ randomly chatters with no signal
present, the amount of time it takes for 4 consecutive
bad bits to happen is random. Therefore, the duration of
polling time is random without signal.
If enough consecutive valid bits are found, DO is
released and the MICRF219A stays on in the continuous
receive mode. Once the chip is in continuous receive
mode, it will not go back to sleep automatically when RF
signal
programmed again to put the MICRF219A back into
auto-polling mode.
Squelch Operation
Squelch operation can be used to limit the amount of
activity on the DO pin during normal operation, which is
particularly useful when interrupts generated on DO can
interfere with correct operation. Using squelch is not
recommended for systems that can program the chip
into auto-polling mode, since it suppresses more activity
on DO, and reduces the average current consumption.
When squelch is enabled (SQ pin tied low while register
bit D17 is 0), DO pin goes high once about every 100ms
instead of chattering all the time when squelch is
disabled.
Figure 6. One Bad Bit Followed by Two Valid Bits
is
removed.
[e-mail]
A “bad bit” is a mark or space with
The
register
or [phone]
M9999-071811-A
bits
MICRF219A
must
be