The transmitter RF output power is proportional to the input current to the
TXMOD pin. A series resistor is used to adjust the peak transmitter output
power. 1.5 dBm of output power requires about 450 µA of input current.
Transmitter Mode Control
The three transmitter operating modes – transmit ASK, transmit OOK, and
power-down (sleep), are controlled by the Modulation & Bias Control func-
tion, and are selected with the CNTRL1 and CNTRL0 control pins. Setting
CNTRL1 high and CNTRL0 low place the unit in the ASK transmit mode.
Setting CNTRL1 low and CNTRL0 high place the unit in the OOK transmit
mode. Setting CNTRL1 and CNTRL0 both low place the unit in the power-
down mode. (Note that the resistor driving TXMOD must also be low in the
power-down mode to minimize power-down current.) CNTRL1 and
CNTRL0 are CMOS compatible inputs. These inputs must be held at a log-
ic level; they cannot be left unconnected.
Turn-On Timing
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. The
total turn-on time to stable transmitter operation for a 10 ms power supply
rise time is 15 ms.
Sleep and Wake-Up Timing
The maximum transition time from either transmit mode to the sleep mode
(t
TOS
and t
TAS
) is 10 µs after CNTRL1 and CNTRL0 are both low (1 µs fall
time).
The maximum time required to switch from the sleep mode to either trans-
mit mode (t
STO
and t
STA
) is 16 µs. Most of this time is due to the start-up of
the transmitter oscillator.
Transmitter Pin Out
GND1
1
VCC1
NC
NC
NC
NC
NC
TXMOD
NC
2
3
4
5
6
7
8
9
10
GND2
11
NC
20
RFIO
B
SM-20H Package Drawing
C
D
E
19
18
17
16
15
14
13
12
GND3
CNTRL0
CNTRL1
VCC2
NC
NC
NC
H
A
F
NC
G
.1225
.1625
.1475
.1875
mm
Dimension
Min
A
.370
.345
.305
.265
.225
Inches
Max
10.135
6.985
2.032
1.905
0.635
1.143
3.429
1.651
Min
.389
.265
.070
.065
.015
.035
.125
.055
Nom
.395
.270
.076
.070
.020
.040
.130
.060
Max
.400
.275
.080
.075
.025
.045
.135
.065
.435
Nom
10.033
6.858
1.930
1.778
0.508
1.016
3.302
1.524
9.881
6.731
1.778
1.651
0.381
0.889
3.175
1.397
B
C
D
E
.185
.145
.09
.105
.065
0.000
.090
.220
.310
F
G
H
0.000
Dimensions in inches.
SM-20H PCB Pad Layout
RF Monolithics, Inc.
Phone: (972) 233-2903
Fax: (972) 387-8148
RFM Europe
Phone: 44 1963 251383
Fax: 44 1963 251510
©1999 by RF Monolithics, Inc. The stylized RFM logo are registered trademarks of RF Monolithics, Inc.
E-mail: info@rfm.com
http://www.rfm.com
TX6001-070805
Page 4 of 6
RFM [ RF MONOLITHICS, INC ]
