Transceiver Event Timing
Peak Detector Timing
Transceiver event timing is summarized in Table 1. Please refer to this ta-
ble for the following discussions.
The Peak Detector attack time constant is set by the value of the capacitor
at the PKDET pin. The attack time t
= C
/4167, where t
is in µs
PKA
PKA
PKD
and C
is in pF. The Peak Detector decay time constant
PKD
Turn-On Timing
t
= 1000*t
.
PKA
PKD
The maximum time t required for the receive function to become opera-
PR
Pulse Generator Timing
tional at turn on is influenced by two factors. All receiver circuitry will be op-
erational 5 ms after the supply voltage reaches 2.2 Vdc. The BBOUT-
CMPIN coupling-capacitor is then DC stabilized in 3 time constants
In the low data rate mode, the interval t
ON pulse to the first RF amplifier and the rising edge of the next ON pulse
between the falling edge of an
PRI
(3*t
). The total turn-on time to stable receiver operation for a 10 ms
to the first RF amplifier is set by a resistor R between the PRATE pin and
BBC
PR
power supply rise time is:
ground. The interval can be adjusted between 0.1 and 5 µs with a resistor
in the range of 51 K to 2000 K. The value of the R is given by:
PR
t
= 15 ms + 3*t
PR
BBC
R
= 404* t
+ 10.5, where t
is in µs, and R is in kilohms
PRI PR
PR
PRI
The maximum time required for either the OOK or ASK transmitter mode to
become operational is 5 ms after the supply voltage reaches 2.2 Vdc.
In the high data rate mode (selected at the PWIDTH pin) the receiver RF
amplifiers operate at a nominal 50%-50% duty cycle. In this case, the peri-
od t
Receive-to-Transmit Timing
from the start of an ON pulse to the first RF amplifier to the start of
PRC
After turn on, the maximum time required to switch from receive to either
transmit mode is 12 µs. Most of this time is due to the start-up of the trans-
mitter oscillator.
the next ON pulse to the first RF amplifier is controlled by the PRATE re-
sistor over a range of 0.1 to 1.1 µs using a resistor of 11 K to 220 K. In this
case R is given by:
PR
Transmit-to-Receive Timing
R
= 198* t
- 8.51, where t
is in µs and R is in kilohms
PRC PR
PR
PRC
The maximum time required to switch from the OOK or ASK transmit mode
In the low data rate mode, the PWIDTH pin sets the width of the ON pulse
to the first RF amplifier t with a resistor R to ground (the ON pulse
to the receive mode is 3*t
, where t
is the BBOUT- CMPIN coupling-
BBC
BBC
PW1
PW
capacitor time constant. When the operating temperature is limited to 60
width to the second RF amplifier t
is set at 1.1 times the pulse width to
PW2
o
C, the time required to switch from transmit to receive is dramatically less
the first RF amplifier in the low data rate mode). The ON pulse width t
PW1
for short transmissions, as less charge leaks away from the
BBOUT-CMPIN coupling capacitor.
can be adjusted between 0.55 and 1 µs with a resistor value in the range
of 200 K to 390 K. The value of R
is given by:
PW
Sleep and Wake-Up Timing
R
= 404* t
- 18.6, where t
is in µs and R
is in kilohms
PW
PW
PW1
PW1
The maximum transition time from the receive mode to the power-down
However, when the PWIDTH pin is connected to Vcc through a 1 M resis-
tor, the RF amplifiers operate at a nominal 50%-50% duty cycle, facilitating
high data rate operation. In this case, the RF amplifiers are controlled by
the PRATE resistor as described above.
(sleep) mode t is 10 µs after CNTRL1 and CNTRL0 are both low
RS
(1 µs fall time).
The maximum transition time from either transmit mode to the sleep mode
(t
and t
) is 10 µs after CNTRL1 and CNTRL0 are both low
TOS
TAS
LPF Group Delay
(1 µs fall time).
The low-pass filter group delay is a function of the filter 3 dB bandwidth,
which is set by a resistor R
The maximum transition time t from the sleep mode to the receive mode
is 3*t
stant. When the operating temperature is limited to 60 C, the time required
to switch from sleep to receive is dramatically less for short sleep times, as
less charge leaks away from the BBOUT- CMPIN coupling capacitor.
SR
to ground at the LPFADJ pin. The minimum
LPF
, where t
is the BBOUT-CMPIN coupling-capacitor time con-
BBC
BBC
3 dB bandwidth f
hms.
= 1445/R , where f
is in kHz, and R
is in kilo-
LPF
LPF
LPF
LPF
o
The maximum group delay t
= 1750/f
= 1.21*R , where t
is in
FGD
FGD
LPF
LPF
µs, f
in kHz, and R
in kilohms.
LPF
LPF
The maximum time required to switch from the sleep mode to either trans-
mit mode (t
and t
) is 16 µs. Most of this time is due to the start-up of
STO
STA
the transmitter oscillator.
AGC Timing
The maximum AGC engage time t
is 5 µs after the reception of a -30
AGC
dBm RF signal with a 1 µs envelope rise time.
The minimum AGC hold-in time is set by the value of the capacitor at the
AGCCAP pin. The hold-in time t
= C
/19.1, where t
is in µs and
AGH
AGH
AGC
C
is in pF.
AGC
RF Monolithics, Inc.
RFM Europe
Phone: (972) 233-2903
Phone: 44 1963 251383
Fax: (972) 387-8148
Fax: 44 1963 251510
E-mail: info@rfm.com
http://www.rfm.com
TR3003-070105
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