HT82K75REW datasheet(55/103 Pages) HOLTEK

55 / 103 page

HT82M75REW/HT82K75REW

Rev. 1.00

June 11, 2010

DC-DC Converter

There are two ways to supply power to the RF Trans-

ceiver. One is through the on-chip DC-DC converter and

the other is without the DC-DC converter. With DC-DC

converter, the RF Transceiver consumes lower current.

With the DC-DC converter, power pins including

VDD_RF1, VDD_RF2, VDD_D, VDD_A, VDD_PLL and

VDD_CP should be hardwired to the DC-DC converter

output, pin VDD_2V2 of the RF Transceiver. Without

DC-DC converter, all the power pins should be directly

hardwired to the external supplied voltage.

For this device the on-chip DC-DC converter is not

used. User can set LREG0x250 [4] to

¢0¢ and

LREG0x273 to

²0x4E² to bypass the DC-DC converter.

When the DC-DC converter is bypassed, pins

VDD_2V2 and VDD_3V are shorted internally.

Battery Monitor

The RF Transceiver provides a function to monitor the

RF Transceiver supplied voltage. A 4-bit voltage thresh-

old can be configured so that when the supplied voltage

is lower than the threshold, the system will be notified.

For battery monitor function, please refer to the Section

named Battery Monitor Operations.

Power Saving Modes

The RF Transceiver power modes are classified into the

following four modes:

· IDLE: RF circuit off. The regulator, oscillator, and digi-

tal circuits are on.

· STANDBY: RF/MAC/BB shutdown with sleep and

32MHz clocks remain active

· DEEP_SLEEP: All power is shutdown except the

power to the digital circuits and registers and FIFOs

data are retained.

· POWER_DOWN: All power is shutdown. Registers

and FIFOs data are not retained, a wake-up input sig-

nal can wake up the RF Transceiver.

IDLE mode is rarely used because the device should at

least always turns on its RX circuit to capture the on-air

RF signals. The only difference between STANDBY

mode and DEEP_SLEEP mode is the power status of

the sleep clock. To wake the RF Transceiver up, the

MCU host has to control the time of sleep process.

The power management control is used for the low

power operation of MAC and baseband modules. It

manages to turn on and off the 32 MHz clock when the

RF Transceiver goes into power saving mode. By turn-

ing off the 32 MHz clock, the MAC and baseband circuits

become inactive regardless whether their power sup-

plies exist or not. All the digital modules are clock-gated

automatically. That means only when a module is func-

tioning, its clock would then be turned on. This approach

efficiently decreases certain amount of the current con-

sumption.

RF Transceiver Interfacing Block

The interfacing block mainly includes three parts named

SPI interface, GPIO and Interrupt signal. Each of them

is described as followings.

SPI Interface

The MCU communicates with the RF Transceiver via an

internal SPI interface to read/write the control registers

and FIFOs. The SPI interface connected to the MCU

SPI master in the RF Transceiver has the following fea-

tures:

· A 4-line slave SPI interface composed of: SEN (SPI

enable), SCLK (SPI Clock), SI (Serial Data Input) and

SO (Serial Data Output).

· Most significant bit (MSB) of all addresses and data

transfers on the SPI interface is done first.

Block Diagram of Voltage Regulators with DC-DC Converter On/Bypass

HT82K75REW Datasheet(PDF) 55 Page - Holtek Semiconductor Inc

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