FM IF RECEIVER WITH RSSI
S1T8514B
1
INTRODUCTION
The S1T8514B is designed for FM IF detection on the pager set. It
includes a voltage regulator, low battery detection circuit, mixer,
oscillator, FSK comparator and limiting IF Amplifier. Also S1T8514B
provides the RSSI function for RF level monitoring.
FEATURES
Built-in RSSI function
Operating voltage range: V
CC
= 1.1 to 4.0V
Low current consumption: I
CC
= 1.5mA
Low battery detection circuit (alarm function): 1.05V
Voltage regulator: Vreg = 1.0V (Typ.)
Mixer operating frequency: 10 to 50MHz
High transmitting rate: 1200 / 2400bps
FSK Data reception
Package type: 20-SSOP (0.65mm)
ORDERING INFORMATION
Device
Package
Operating Temperature
S1T8514B01-V0B0
20
-
SSOP
-
225
-
20
C to +70
C
20
-
SSOP
-
225
FM IF RECEIVER WITH RSSI
S1T8514B
3
PIN DESCRIPTION
ABSOLUTE MAXIMUM RATINGS
Pin No
Symbol
Description
1
OSCI
Oscillator input (Base). The oscillator is an internally biased colpitts type.
2
OSCO
Oscillator output.
3
MO
Mixer output (Output impedance
2k
)
Connect a 455kHz filter between this pin and the LI.
4
V
CC
V
CC
pin.
5
LI
IF limiter amplifier input (Input impedance
2k
)
6
LD
Bypass capacitor connect pin for the IF limiter amplifier.
7
FSKI
Differential Amp Reference input on the FSK comparator.
8
QD
Quadrature detection, phase shifter input.
9
RAO
Recovered audio signal output.
10
RSSI
Output pin for RSSI. This pin detects RF level by monitoring the limiter amplifier.
11
LPFI
Low pass filter a amplifier input. Bias is supplied from pin 9.
12
LPFO
Low pass filter amplifier output.
13
BSC
Battery saving control pin.
High: Battery saving off. Low: Battery saving on.
14
QC
Quick charge control pin.
High: Quick charge-discharge on. Low: Quick charge-discharge off.
15
FSKO
FSK signal output pin.
16
AO
Alarm output. This pin becomes High when VCC drops belows 1.05V.
17
REGC
S1T8514B has an internal PNP transistor.
But, it also can support an external PNP transistor to control the power.
18
REGO
Regulated Voltage output.
19
GND
Ground.
20
MI
Mixer input impedance
5k
.
Characteristic
Symbol
Value
Unit
Max. Supply Voltage
V
CC (MAX)
4
V
Power Dissipation
P
D
800
mW
Operating Temperature
T
OPR
-
20 to +70
C
Storage Temperature
T
STG
-
55 to +125
C
S1T8514B
FM IF RECEIVER WITH RSSI
4
ELECTRICAL CHARACTERISTICS
(V
CC
= 1.4V
5%, f
IN
(2MIX)
= 21.4MHz, f
DEV
=
4.8kHz, f
MOD
= 600Hz, Ta = 25
C, unless otherwise specified)
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
Operating current
I
CCN
No Input Signal
-
1.2
1.7
mA
I
CCS
Battery Saving
-
0
10
A
Alarm detection voltage
V
AD
-
1.0
1.05
1.1
V
Alarm low level output voltage
V
O (AL)
I = 100
A
-
-
0.4
V
Alarm high level leakage current
I
LKG (AL)
-
-
-
2
A
FSK low level output voltage
V
L (FSK)
-
-
-
0.4
V
FSK high level leakage current
I
LKG (FSK)
I = 100
A
-
-
2
A
Regulator output voltage
V
OREG
-
0.95
1.0
1.05
V
Quick charge current
I
C
-
56
70
-
A
Input for
-
3dB sensitivity
V
LIM
Mixer Input
-
2.5
7.5
Vrms
Input for
-
12dB SINAD
sensitivity
V
I (SEN)
FM Input
-
6.0
18.0
Vrms
Recovered audio output voltage
V
O (RAO)
V
IN (2MIX)
= 500
Vrms
33
55
77
mVrms
Mixer conversion voltage gain
G
V (M)
Ceramic Filter loss =
-
1dB
8
12
16
dB
Signal to noise ratio
S/N
-
38
55
-
dB
Total Harmonic Distortion
THD
-
-
2.0
3.5
%
Mixer 3rd order intercept point
3RD
-
-
-
10
-
dBm
Mixer input resistance
R
I (MIX)
-
3.5
5
6.5
k
Limiting amp input resistance
R
I (LA)
-
1.4
2
2.6
k
AM rejection ratio
AMR
V
IN (2MIX)
= 5
Vrms
(AM = 300%)
25
40
-
dB
Data shaping output duty
DR
V
IN (2MIX)
= 500
Vrms
40
50
60
%
RSSI output voltage
V
RSSI
V
IN (2MIX)
= 1m
Vrms
(AM = 300%)
0.49
0.7
0.91
V
RSSI output resistance
R
RSSI
-
80
100
120
k
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