Pin Descriptions
Pin
1
2
3
4
5
6
7
Name
GND1
VCC1
NC
NC
NC
NC
NC
Description
GND1 is the RF ground pin. GND2 and GND3 should be connected to GND1 by short, low-inductance traces.
VCC1 is the positive supply voltage pin for the transmitter output amplifier and the transmitter base-band circuitry.
VCC1 is usually connected to the positive supply through a ferrite RF decoupling bead which is bypassed by an
RF capacitor on the
supply side.
See the description of VCC2 (Pin 16) for additional information.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
The transmitter RF output voltage is proportional to the input current to this pin. A series resistor is used to adjust
the peak transmitter output voltage. 0 dBm of output power requires 250 µA of input current. In the ASK mode,
minimum output power occurs when the modulation driver sinks about 10 µA of current from this pin. In the OOK
mode, input signals less than 220 mV completely turn the transmitter oscillator off. Internally, this pin appears to
be a diode in series with a small resistor. Peak transmitter output power P
O
for a 3 Vdc supply voltage is approxi-
mately:
P
O
= 16*(I
TXM
)
2
, where P
O
is in mW, and the peak modulation current I
TXM
is in mA
A ±5% resistor value is recommended. In the OOK mode, this pin is usually driven with a logic-level data input
(unshaped data pulses). OOK modulation is practical for data pulses of 200 µs or longer. In the ASK mode, this
pin accepts analog modulation (shaped or unshaped data pulses). ASK modulation is practical for data pulses
8.7 µs or longer. This pin must be low in the power-down (sleep) mode. Please refer to the
ASH Transceiver De-
signer’s Guide
for additional information on modulation techniques.
9
10
11
12
13
14
15
16
NC
GND2
NC
NC
NC
NC
NC
VCC2
No connection. Printed circuit board pad may be grounded or floating.
GND2 is an IC ground pin. It should be connected to GND1 by a short, low inductance trace.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
No connection. Printed circuit board pad may be grounded or floating.
VCC2 is the positive supply voltage pin for the transmitter oscillator. Pin 16 must be bypassed with an RF capaci-
tor, and must also be bypassed with a 1 to 10 µF tantalum or electrolytic capacitor. Power supply voltage ripple
should be limited to 10 mV peak-to-peak. See the
ASH Transceiver Designer’s Guide
for additional information.
CNTRL1 and CNTRL0 select the transmit modes. CNTRL1 high and CNTRL0 low place the unit in the ASK trans-
mit mode. CNTRL1 low and CNTRL0 high place the unit in the OOK transmit mode. CNTRL1 and CNTRL0 both
low place the unit in the power-down (sleep) mode. CNTRL1 is a high-impedance input (CMOS compatible). An
input voltage of 0 to 300 mV is interpreted as a logic low. An input voltage of Vcc - 300 mV or greater is inter-
preted as a logic high. An input voltage greater than Vcc + 200 mV should not be applied to this pin. A logic high
requires a maximum source current of 40 µA. A logic low requires a maximum sink current of 25 µA (1 µA in sleep
mode). This pin must be held at a logic level; it cannot be left unconnected.
CNTRL0 is used with CNTRL1 to control the operating modes of the transmitter. See the description of CNTRL1
for more information.
GND3 is an IC ground pin. It should be connected to GND1 by a short, low inductance trace.
RFIO is the transmitter RF output pin. This pin is connected directly to the SAW filter transducer. Antennas pre-
senting an impedance in the range of 35 to 72 ohms resistive can be satisfactorily matched to this pin with a se-
ries matching coil and a shunt matching/ESD protection coil. Other antenna impedances can be matched using
two or three components. For some impedances, two inductors and a capacitor will be required. A DC path from
RFIO to ground is required for ESD protection.
8
TXMOD
17
CNTRL1
18
19
CNTRL0
GND3
20
RFIO
5
RFM [ RF MONOLITHICS, INC ]
