TC35680FSG datasheet(35/91 Pages) TOSHIBA

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TC35680FSG-002/TC35681FSG-002

2019-04-04

4.4. Power Supply

VBAT and VDDIO

TC35680/TC35681 have a main power supply VBAT and an I/O power supply VDDIO. VBAT and VDDIO can be supplied with one

power source or with individual power sources.

When the source of the VDDIO is different from the source of the VBAT, the voltage of the VDDIO should not exceed the voltage of

the VBAT. For each range of the operation voltage, refer to Section 5.2. For the example of the connection, refer to Chapter 6.

Voltage Step-Down DC/DC Converter and LDO Regulator

TC35680/TC35681 integrate a DC/DC converter and multiple LDO regulators. The DC/DC converter or the LDO regulator can be

selected as the power supply source in the normal operating mode (the Active mode). The selection is done at the shipment of a

device. So, it cannot be done by an external control in software. A commodity product uses the DC/DC converter. The LDO

regulator can be used by a customized product.

The DC/DC converter reduces the power consumption. It needs an external inductor. On the other hand, the LDO regulator needs

no inductors, which reduces some discrete components and the area of the board. The power source should be selected to

optimize the performance of the application system.

As a low power consumption function, the PMU switches automatically the power source between the DC/DC converter and the

LDO regulator to save power efficiently. And it changes the voltage of the source at the same time to reduce more power

consumption. When a user only sets a mode of a low power consumption function, the PMU controls the power source

automatically to save the power. For the details of the low power consumption function, refer to Section 3.6. And, for the details of

the output voltage, refer to Chapter 5.

Table 4-2 shows the output and input pins of the power supply when the DC/DC converter or the LDO regulator is used.

Table 4-2 Input and output pins of power supply

Pin name

DC/DC converter operation

LDO regulator operation

Output

Hi-Z

VDDCORE1

Input

VDDCORE2

Input

Output

When the output power of the RF wireless communication is 8 dBm, it is strongly recommended that a proper LC filter is connected

to the VDDCORE1 and VDDCORE2 pins, respectively, to reduce the noise which affects the RF characteristics. The details of the

connection of the LC filter, refer to Chapter 6 and the “Hardware Application Note”.

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