Rev 1 - November 2008
©2008 Semtech Corp.
SX1781
www.semtech.com
Page 1
PLL Frequency Synthesizer with Integrated VCO
ADVANCED COMMUNICATIONS & SENSING FINAL
DATASHEET
The SX1781 is a high-performance low phase noise
integer-N frequency synthesizer for wireless
communications applications. The circuit embeds a
fully integrated PLL (including VCO tank and loop
filter), complementary output buffers The divider and
power-down settings are programmable via an SPI
interface. A Lock Detector pin linked to a squelch
function have been designed to ease the software
development.
Frequency range:1200 to 1400 MHz
Frequency step: 250 kHz min.
Phase noise: -85 dBc/Hz @ 10 kHz offset
Reference spurs: -67 dBc
Hopping time: 350
µ
s max.
Operating voltage: 3.0 - 3.6V
Programmable Output Power: up to +5 dBm
Integrated VCO and loop filter
SPI-bus interface
Lock Detect output and squelch
Ultra-low power sleep mode
Complementary RF outputs
Temperature range: -40 to +85°C
4 x 4 mm MLPQ16 package
Pb-free and RoHS compliant
GENERAL DESCRIPTION
PIN DIAGRAM
BLOCK DIAGRAM
FEATURES
ORDERING INFORMATION
Part Number Delivery Quantity
SX1781IMLTRT Tape & Reel 3000 pces
VDDA VDDD
V
DDF
VSSA VSSD VSSF
LD
÷ 2
CSB SCK MOSI MISO
CLK
÷ [N Div+4800]
VCO
Out_P
Out_N
Loop
Filter
PFD
SLEEPB
÷[RDiv+1]
Rev 1 - November 2008
©2008 Semtech Corp.
SX1781
www.semtech.com
Page 2
PLL Frequency Synthesizer with integrated VCO
ADVANCED COMMUNICATIONS & SENSING FINAL
DATASHEET
1. Pin Description
Table 1 Pin Description
Note: the thermal pad under the SX1781 should be connected to ground for an optimal thermal dissipation.
Pin # Pin Name Pin Type Description
1 VDDD Power Supply
2 CLK I PLL Reference Signal
3 NC Do not Connect
4 VSSD Ground
5 CSB I SPI Line Select
6 MOSI I SPI Data Input
7 MISO O SPI Data Output (High Z when unused)
8 SCK I SPI Clock
9 VSSA Ground
10 Out_N O RF Complementary Output
11 Out_P O RF Output
12 VDDA Power Supply, Output Buffers
13 VSSF Ground
14 VDDF Power Supply
15 SLEEPB I When low, the circuit is in deep sleep mode
16 LD O PLL Lock Detect Output (active high)
Rev 1 - November 2008
©2008 Semtech Corp.
SX1781
www.semtech.com
Page 3
PLL Frequency Synthesizer with integrated VCO
ADVANCED COMMUNICATIONS & SENSING FINAL
DATASHEET
2. Electrical Characteristic
2.1. ESD and Latchup Notice
The SX1781 is a high performance radio frequency device. It withstands:
2 kV ESD discharge with the Human Body Model (Class 2 of the JEDEC standard JESD22-A114-B)
1 kV ESD discharge with the Charged Device Model (Class IV of JESD22-C101C)
+/- 100 mA Static Latchup current at maximum temperature (Class II Level A of JESD78)
It should be handled with all the necessary ESD precautions to avoid any permanent damage.
2.2. Maximum Ratings
Important Note: The Absolute Maximum Ratings, in Table 1, are stress ratings only, and functional operation of the device
at conditions other than those indicated in the Operating Conditions sections of this specification are not implied. Exposure
to the absolute maximum ratings, where different to the operating conditions, for an extended period may reduce the
reliability or useful lifetime of the product.
Table 2 Absolute Maximum Ratings
Parameter Symbol Minimum Maximum Units
Supply Voltage VDDA, VDDD, VDDF
V
DD
-0.5 3.7 V
Input Voltage (non-supply pins)
Vin - 3.7 V
Output Voltage (non-supply pins)
Vout - 3.7 V
Ambient Operating Temperature Range
TA -40 +85 °C
Storage Temperature
Tstor -50 +150 °C

SX1781IMLTRT

Mfr. #:
Manufacturer:
Semtech
Description:
Phase Locked Loops - PLL PLL FREQ SYNTH WITH VCO
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
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