ZHCS363L August 2011 – March 2017 TRF7970A
PRODUCTION DATA.
The first gain and filtering stage has a nominal gain of 15 dB with an adjustable band-pass filter. The band-pass filter has programmable 3-dB corner frequencies between 110 kHz to 450 kHz for the high-pass filter and 570 kHz to 1500 kHz for the low-pass filter. After the band-pass filter, there is another gain-and-filtering stage with a nominal gain of 8 dB and with frequency characteristics identical to the first band-pass stage.
The internal filters are configured automatically depending on the selected ISO communication standard in the ISO Control register (address 0x01). If required, additional fine tuning can be done by writing directly to the RX Special Setting registers (address 0x0A).
Table 6-5 shows the various settings for the receiver analog section. Setting B4, B5, B6, and B7 to 0 results in a band-pass characteristic of 240 kHz to 1.4 MHz, which is appropriate for ISO/IEC 14443 B 106 kbps, ISO/IEC 14443 A and B data rates of 212 kbps and 424 kbps, and FeliCa 424 kbps.
Function: Sets the gains and filters directly | |||
Default: 0x40 at POR = H or EN = L, and at each write to the ISO Control register (0x01). When bits B7, B6, B5 and B4 are all zero, the filters are set for ISO/IEC 14443 B (240 kHz to 1.4 MHz). | |||
Bit | Name | Function | Description |
B7 | C212 | Band-pass 110 kHz to 570 kHz | Appropriate for 212-kHz subcarrier system (FeliCa) |
B6 | C424 | Band-pass 200 kHz to 900 kHz | Appropriate for 424-kHz subcarrier used in ISO/IEC 15693 |
B5 | M848 | Band-pass 450 kHz to 1.5 MHz | Appropriate for Manchester-coded 848-kHz subcarrier used in ISO/IEC 14443 A and B |
B4 | hbt | Band-pass 100 kHz to 1.5 MHz Gain reduced for 18 dB |
Appropriate for highest bit rate (848 kbps) used in high-bit-rate ISO/IEC 14443 |
B3 | gd1 | 00 = Gain reduction 0 dB 01 = Gain reduction for 5 dB 10 = Gain reduction for 10 dB 11 = Gain reduction for 15 dB |
Sets the RX gain reduction and reduces sensitivity |
B2 | gd2 | ||
B1 | Reserved | ||
B0 | Reserved |