U2781B

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-...