6.3 Supply Arrangements

Regulator Supply Input: VIN

The positive supply at VIN (pin 2) has an input voltage range of 2.7 V to 5.5 V. VIN provides the supply input sources for three internal regulators with the output voltages VDD_RF, VDD_A, and VDD_X. External bypass capacitors for supply noise filtering must be used (per reference schematics).

RF Power Amplifier Regulator: VDD_RF

The VDD_RF (pin 3) regulator is supplying the RF power amplifier. The voltage regulator can be set for either 5-V or 3-V operation. External bypass capacitors for supply noise filtering must be used (per reference schematics). When configured for 5-V manual operation, the VDD_RF output voltage can be set from 4.3 V to 5 V in 100-mV steps. In 3-V manual operation, the output can be programmed from 2.7 V to 3.4 V in 100-mV steps (see Table 6-2). The maximum output current capability for 5-V operation is 150 mA and for 3-V operation is 100 mA.

Analog Supply Regulator: VDD_A

Regulator VDD_A (pin 1) supplies the analog circuits of the device. The output voltage setting depends on the input voltage and can be set for 5-V and 3-V operation. When configured for 5-V manual operation, the output voltage is fixed at 3.4 V. External bypass capacitors for supply noise filtering must be used (per reference schematics). When configured for 3-V manual operation, the VDD_A output can be set from 2.7 V to 3.4 V in 100-mV steps (see Table 6-2).

Digital Supply Regulator: VDD_X

The digital supply regulator VDD_X (pin 32) provides the power for the internal digital building blocks and can also be used to supply external electronics within the reader system. When configured for 3-V operation, the output voltage can be set from 2.7 to 3.4 V in 100-mV steps. External bypass capacitors for supply noise filtering must be used (refer to the reference schematics).

The RF power amplifier regulator (VDD_RF), analog supply regulator (VDD_A), and digital supply regulator (VDD_X) can be configured to operate in either automatic or manual mode described in Table 6-1. The automatic regulator setting mode ensures an optimal compromise between PSRR and the highest possible supply voltage to ensure maximum RF power output.

By default, the regulators are set in automatic regulator setting mode. In this mode, the regulators are automatically set every time the system is activated by setting EN input High or each time the automatic regulator setting bit, B7 in register 0x0B is set to a 1. The action is started on the 0 to 1 transition. This means that, if the user wants to rerun the automatic setting from a state in which the automatic setting bit is already high, the automatic setting bit (B7 in register 0x0B) should be changed: 1-0-1.

By default, the regulator setting algorithm sets the regulator outputs to a "Delta Voltage" of 250 mV below VIN, but not higher than 5 V for VDD_RF and 3.4 V for VDD_A and VDD_A. The "Delta Voltage" in automatic regulator mode can be increased up to 400 mV (for more details, see bits B0 to B2 in register 0x0B).

Power Amplifier Supply: VDD_PA

The power amplifier of the TRF7962A is supplied through VDD_PA (pin 4). The positive supply pin for the RF power amplifier is externally connected to the regulator output VDD_RF (pin 3).

I/O Level Shifter Supply: VDD_I/O

The TRF7962A has a separate supply input VDD_I/O (pin 16) for the build in I/O level shifter. The supported input voltage ranges from 1.8 V to VIN, however not exceeding 5.5 V. Pin 16 is used to supply the I/O interface pins (I/O_0 to I/O_7), IRQ, SYS_CLK, and DATA_CLK pins of the reader. In typical applications, VDD_I/O is directly connected to VDD_X while VDD_X also supplies the MCU. This ensures that the I/O signal levels of the MCU match with the logic levels of the TRF7962A.

Negative Supply Connections: VSS, VSS_RX, VSS_A, VSS_PA

The negative supply connections VSS_X of each functional block are all externally connected to GND.

The substrate connection is VSS (pin 10), the analog negative supply is VSS_A (pin 15), the logic negative supply is VSS_D (pin 29), the RF output stage negative supply is VSS_PA (pin 6), and the negative supply for the RF receiver VSS_RX (pin 7).