Frequency Synthesizer
U2781B
Frequency Synthesizer
Description
The programmable frequency synthesizer IC U2781B for µP-controlled applications...
Description
U2781B
Frequency Synthesizer
Description
The programmable frequency synthesizer IC U2781B for µP-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-...
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