MICRF221 3.3V, QwikRadio 850 MHz to 950 MHz Receiver General Description Features The MICRF221 is a third generation QwikRadio Complete receiver on a chip -2 receiver, offering all the benefits of Micrel s earlier -109dBm sensitivity, 1kbps, and BER 10 QwikRadio products with significant improvements, Image rejection mixer including: enhanced sensitivity, automatic duty-cycle 850MHz to 950MHz frequency range feature and RSSI output. Low power, 9mA 868MHz, continuous on The MICRF221 is a super-heterodyne receiver, Data rates to 10kbps (Manchester Encoded) designed for OOK and ASK modulation. The down- conversion mixer also provides image rejection. Auto polling (sleep mode, current < 0.1 mA) The MICRF221 receiver provides a SLEEP Mode for Analog RSSI output duty-cycle operation and an enhanced, customer Programmable low sensitivity mode programmableWAK function. These features are No IF filter required further combined into a wholly integratedself-pollin Excellent selectivity and noise rejection scheme that is ideal for low and ultra-low power applications, such as RKE and RFID Low external part count All post-detection data filtering is provided on the Additional functions programmed through serial MICRF221 receiver. Any one of four filter bandwidths interface may be selected externally by the user in binary steps, from 1.25kHz to 10kHz. The user needs only to program the device with a set of easily determined values based on data rate, code modulation format, and desired duty- cycle operation. Datasheets and support documentation are available on Micrels website at: www.micrel.com. Typical Application Figure 1: MICRF221 Receiver 915.0 MHz, 1kHz Baud Rate Example QwikRadio is a registered trademark of Micrel, Inc. Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel Inc. MICRF221 Ordering Information Part Number Temperature Range Package MICRF221AYQS 40 to +105C 16-Pin QSOP Pin Configuration 16-Pin QSOP (QS) Pin Description 16-Pin Pin Pin Function QSOP Name Reference Oscillator (input): Reference resonator input connection to pierce oscillator stage. May also be 1 RO1 driven by external reference signal of 1.5V p-p amplitude maximum. 7pF to GND during normal operation. 2 GNDRF Negative supply connection associated with ANT RF input. Antenna (input): RF signal input from antenna. Internally AC coupled. It is recommended a matching network 3 ANT with an inductor-to-RF ground be used to improve ESD protection. 4 GNDRF Negative supply connection associated with ANT RF input. 5 VDD Positive supply connection for all chip functions. Squelch control logic input with an active internal pull-up (3uA typical) pulls the logic-input HIGH when the 6 SQ device is enabled. This feature is not recommended in MICRF221 and this pin should remain floating. Select (input): Logic control input with active 3A (8A max) internal pull-up when not in shutdown or SLEEP 7 SEL0 mode. It does not need to be defined in SLEEP mode. Used in conjunction with SEL1 to control D3 bandwidth LSB when serial interface contains default setting. 8 SHDN Shutdown logic control input. Active internal pull-up. 9 GND Negative supply connection for all chip functions except for RF input. Demodulated data (output): May be blanked until bit checking test is acceptable. A current limited CMOS 10 DO output during normal operation this pin is also used as a CMOS Schmitt input for serial interface data. A 25k pull-down is present when device is in shutdown and sleep modes. Select (input): Logic control input with active 3A (8A max) internal pull-up when not in shutdown or SLEEP 11 SEL1 mode. It does not need to be defined in SLEEP mode. Used in conjunction with SEL0, to control D4 bandwidth MSB, when serial interface contains default setting. Demodulation threshold voltage integration capacitor. Capacitor-to-GND sets the settling time for the 12 CTH demodulation data slicing level. Values above 1nF are recommended and should be optimized for data rate and data profile. 13 CAGC AGC filter capacitor. A capacitor, normally greater than 0.47F, is connected from this pin-to-GND Received signal strength indication (output): Output is from a switched capacitor integrating op amp with 14 RSSI 220 typical output impedance. Serial interface input clock. CMOS Schmitt input. A 25k pull-down is present when device is in shutdown 15 SCLK mode. 16 RO2 Reference resonator connection. 7pF to GND during normal operation. Revision 2.0 2 August 12, 2015