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U2781B
Frequency Synthesizer
Description
The programmable frequency synthesizer IC U2781B for P-controlled applications is realized with Atmel Wireless & Microcontrollers' advanced UHF process which is very suitable for combinations of fast ECL logic and low-current I2L logic. The benefits are high input sensitivity combined with low power consumption and therefore small packages (SSO20). This makes the device a perfect choice for cordless phones and handheld cellular radio sets up to 1.1 GHz. Electrostatic sensitive device. Observe precautions for handling.
Features
D D D D D D D D D Very low current consumption (typ. 3 V/ 5 mA) Supply-voltage range: 2.7 to 5.5 V Max. input frequency: 1.1 GHz Programmable prescaler 64/ 65 or 128/ 129 Controlled by 3-wire bus with fclock up to 500 kHz Status output for PLL lock/ unlock condition Very fast phase detector SSO20 package ESD protection in accordance with MIL-STD. 883 method 3015 class 2
Benefits
D Very low current consumption extends talk time D Few external components and SSO package save costs and space
Block Diagram
Osci Osco VS GND 1 3 5 7 1-bit latch load control 18-bit shift register Phase detector Charge pump 15-bit latch Oscillator 14-bit reference counter Mo 17 LDo 8 VSCP 4 CP 6
Clock 11 Data 13 Enable 14
18-bit latch Prescaler 64/65 128/129 7-bit swallow counter 11-bit main counter
15
PS
RFi 10
U2781B
Figure 1. Block diagram
Rev. A4, 11-Sep-00
1 (10)
U2781B
Ordering Information
Extended Type Number U2781B-MFS U2781B-MFSG3 SS020 SS020 Package Remarks Tube, MOQ 830 pcs Taped and reeled, MOQ 4000 pcs
Functional Description
The IC is controlled by a 3-wire bus with Clock, Data and Enable inputs for programming the scaling factors of the programmable counter, the reference counter and the prescaler. A TCXO can be connected to the oscillator input (OSCi) as an alternative solution to the common crystal reference oscillator. In that case, the oscillator output (OSCo) should be left open. The charge-pump output operates as switched current sources. The characteristics of the phase-locked loop can be determinated by the external lowpass filter. The phase characteristic of the phase detector is convertible and thus matchable to different frequency/ tuning voltage characteristics.
Pin Description
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1 2 3 4 5 6 7 8 9 Osci n.c. Oscillator input Not connected Osco Oscillator output VSCP Vs Charge-pump supply voltage Supply voltage CP Charge-pump output Ground GND LDo n.c. Lock-detector output Not connected VCO input 10 11 RFi Clock n.c. 3-wire bus Clock Not connected 12 13 14 15 16 17 18 19 20 Data 3-wire bus Data Enable PS 3-wire bus Enable Phase select input Not connected n.c. Mo Monitor output for fp and fr Not connected Not connected Not connected n.c. n.c. n.c. 2 (10)
Pin
Symbol
Function
Osci 1 n.c. 2
20 n.c. 19 n.c. 18 n.c. 17 Mo 16 n.c. U2781B 15 PS 14 Enable 13 Data 12 n.c. 11 Clock
Osco 3 VSCP 4 VS CP 5 6
GND 7 LDo 8 n.c. 9
RFi 10
Figure 2. Pinning SSO20
Rev. A4, 11-Sep-00
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Rev. A4, 11-Sep-00 Frequency range RF input Supply current Supply voltage DC supply Junction ambient Supply voltage Bus input voltage RF input Supply voltage Tamb = 25_C, VS = 2.7 to 5.5 V, unless otherwise specified
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Absolute Maximum Ratings
Storage temperature Charge-pump input voltage Phase-select input voltage Oscillator output voltage Oscillator input voltage Parameter Symbol VOsco VBUS VOsci VSCP VRF VPS Tstg VS - 40 to 125 - 0.3 to 6 Value 1.5 VS 6 6 6 1
Electrical Characteristics
Thermal Resistance
Operating Range
Scaling factors main counter
Scaling factor prescaler
Input voltage fi = 200 to 1100 MHz
Supply current CP
Supply voltage CP
Ambient temperature
Parameter
SSO20
Parameter
Parameter
VCP = 5 V, PLL in locked condition
Rs = 50 *) Rs = 50 *)
Vs = 3 V
Test Conditions / Pins
Symbol
Symbol
RthJA
Tamb
Symbol
VS
Vimin Vimax
VSCP
SPSC
fimin fimax
ISCP
SM
Vs
Is
Min.
1100
2.7
Vs
4
- 40 to 85
2.7 to 5.5
Value
Value
140
64/128
50 1250
Typ.
20 200
1
5
U2781B
Max.
2047
5.5
5.5
K/W
Unit
Unit
Unit
mVRMS mVRMS
C
C
V
V
V
V
V
V
V
V
MHz MHz
Unit
mA
A
3 (10) V V
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*) RMS voltage at 50 W Tamb = 25_C, VS = 2.7 to 5.5 V, unless otherwise specified
Electrical Characteristics (continued)
U2781B
4 (10) Leakage current Saturation voltage Lock-detector output (open collector) Leakage current Sink current Source current Charge-pump output Low output voltage High output voltage Monitor output (Emitter follower) Low input current High input current Low input voltage High input voltage 3-wire bus (Clock, Data, Enable) and PS Scaling factor reference counter Frequency range Input voltage Reference oscillator Scaling factors swallow counter Parameter Rs = 50 *) Rs = 50 *) VLD = 5 V ILD = 0.2 mA VCP = 5 V VCP = 5 V IMO = 0.5 mA Vs = 3 V Test Conditions / Pins Symbol Isource Vimin Vimax fimin fimax Ileak Ileak Isink Vsat ViH ViH ViL ViL IiH SR IiL SS Min. 2.1 1.5 -5 0 4 0 Typ. 20 200 0.2 1.8 2.2 0.9 0,1 20 5 -1 1
Rev. A4, 11-Sep-00 16383 Max. 127 0.4 1.9 0.4 5 2 mVRMS mVRMS MHz MHz Unit mA mA A A mA nA V V V V V
U2781B
Functional Description
The reference- and the programmable counter can be programmed by the 3-wire bus (Clock, Data and Enable). The Data Signal is transferred bit by bit into the shift register during the rising edge, starting with the MSB-bit. As soon as the enable signal is in high condition, the content of the shift register will be taken over either into the 15-bit reference counter latch (C = H) or into the 18-bit latch of the programmable counter (C = L)
Reference Counter (15-bit shift register)
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LSB C MSB PSC R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 C: Control bit High PSC: Prescaler scaling factor bit: High - 64/65 Low - 128/129 SPSC = 64 or 128 R0 to R13: These bits are setting the reference counter SR SR = R0 20 + R1 21 + to + R12 212 + R13 permitted scaling factors for SR: 4 to 16383 213
Programmable Counter (18-bit shift register)
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C S0 S1 S2 S3 S4 S5 S6 M0 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 Control bit Low These bits are setting the swallow counter SS. SS = S0 20 + S1 21 + to + S5 25 + S6 26 permitted scaling factors for SS: 0 to 127, SS < SM M0 to M10 : These bits are setting the main counter SM. SM = M0 20 + M1 21 + to + M9 29 + M10 permitted scaling factors for SM: 4 to 2047 C: S0 to S6: 210 Total scaling factor SP of the programmable counter SP = (SPSC SM) + SS Condition: SS < SM
LSB
MSB
VCO Frequency
fVCO = ((SPSC SM) + SS) fRefOsc / SR
Rev. A4, 11-Sep-00
5 (10)
U2781B
Timing 3-Wire Bus
MSB P 17 PSC Data P 16 R 13 P9 R7 P8 R6 P0 R0 LSB C = 0 : Prog. scaler data C = 1 : Reference scaler date
Clock
Enable t5 t1 All times t1 to t5 > 1 ms Figure 3. Timing 3-wire bus t2 t3 t4
Phase-Detector Polarity
The polarity of the phase detector can be changed by the PS input. Depending on the PS input level, the chargepump current will also be inverted. The monitor output signal MO (emitter follower output with ECL level) will be switched over from fP to fR simultaneously.
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CP MO fR fR fR CP MO fP fP fP fR > fP fR < fP fR = fP Isink 0 Isource Isink 0 Isource Depending on the VCO frequency versus tuning voltage characteristic, the PS input has to be programmed as follows: For increasing tuning voltage and increasing frequency: decreasing frequency: PS = High or open PS = Low. 6 (10) Rev. A4, 11-Sep-00
PS = High or Open
PS = Low
U2781B
Pulse Diagram Phase and Lock Detector
fp (fvco/Tp) fr (fosc/Tp) Vcp LD
Figure 4. Pulse diagram phase and lock detector
The LD output is in unlocked condition at low level and the pulsewidth is in reference to the phase respectively frequency difference at the phase detector. If the phase detector output pulses are smaller than 100 ns, the LD output changes to high and indicates "lock" condition.
Test Circuit
Input sensitivity
10 k
Frequency Counter Monitor
Enable Data Clock
U2781B
VS = 3 V
1m
10 n
1n
RF Test Generator
Figure 5. Test circuit
Rev. A4, 11-Sep-00
7 (10)
U2781B
Typical Input Sensitivity
1000 500 200 100 50 20 10 5 2 1 .5 .2 .1 0 200 400 600 800 1000 1200 1400 1600 Frequency ( MHz ) mVRMS ( 50 Ohm) dBm ( 50 Ohm) +10 +5 0 -5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 - 60 - 65
Figure 6. Typical input sensitivity
Application Circuit
Enable Data Clock
U2781B
alternatively to external TCXO 2 x 10p VSCP = 3 to 6 V VS = 3 V 1m 1m 10n Loop filter 10n
Figure 7. Application circuit
10n LD 10k
1n VCO Tuning voltage
8 (10)
Rev. A4, 11-Sep-00
U2781B
Input Impedance
j 0.5j 2j
0.2j
5j
0
-0.2j
-0.5j 1.5 GHz -j
Package Information
Package SSO20
Dimensions in mm
6.75 6.50 5.7 5.3 4.5 4.3
0.25 0.65 5.85 20 11
1
Rev. A4, 11-Sep-00
A AA A AAAA A AA A AAAA
0.2 0.5 1 2 500 MHz 1 GHz
5 100 MHz
1
-5j
-2j Z0 = 50 W
Figure 8. Input impedance
1.30 0.15 0.05 0.15 6.6 6.3
technical drawings according to DIN specifications 13007
10
9 (10)
U2781B
Ozone Depleting Substances Policy Statement
It is the policy of Atmel Germany GmbH to 1. Meet all present and future national and international statutory requirements. 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances (ODSs). The Montreal Protocol (1987) and its London Amendments (1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. Atmel Germany GmbH has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2. Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency (EPA) in the USA 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C (transitional substances) respectively. Atmel Germany GmbH can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances.
3.
We reserve the right to make changes to improve technical design and may do so without further notice. Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use Atmel Wireless & Microcontrollers products for any unintended or unauthorized application, the buyer shall indemnify Atmel Wireless & Microcontrollers against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. Data sheets can also be retrieved from the Internet: http://www.atmel-wm.com
Atmel Germany GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423
10 (10)
Rev. A4, 11-Sep-00

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