MAX2837 Просмотр технического описания (PDF) - Maxim Integrated

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MAX2837

2.3GHz to 2.7GHz Wireless Broadband RF Transceiver

Maxim Integrated 

MAX2837

2.3GHz to 2.7GHz Wireless

Broadband RF Transceiver

Temperature Sensor Readout Through

DOUT Pin

To estimate chip temperature, on-chip temperature sen-

sor is enabled by programming Address 9 D<1> = 1. The

procedure is as follows:

1) Enable temp-sensor by setting Address 9 D<1> = 1.

Roughly 100µs to 1ms time is needed to let the tem-

perature sensor output settle to within 5 to 1 degrees.

2) To trigger temperature sensor ADC, program Address

9 D<0> from “0” to “1”. The ADC will acquire the 5-bit

logic output in 2µs, temperature sensor needs to be

ON (Address 9 D<1> = 1) to maintain the ADC logic

output. Note that the ADC trigger should happen

AFTER the temp sensor is enabled to get the correct

result. Therefore, step 1 and step 2 of this procedure

should be carried out on two separate SPI program-

ming events separated by the temp sensor settling

time.

3) Note that after the ADC latches its output and you

desire to retake another temp sensor temperature

reading value, the ADC has to be retriggered to reac-

quire a new temp sensor value (assuming the temp

sensor is already enabled). To do so, program Address

9 D<0> from “1” to “0” then from “0” to “1”. After the

ADC latches it digital output in 2µs it shuts off.

4) To read the 5-bit logic output through DOUT pin,

apply 4-wire SPI readout programming sequence to

Address 7.

VAS Operating Procedure

After power-up, program Address 22 D<1> = 0 such that

VAS frequency acquisition starts from VCO band 15,

it reduces the worst-case acquisition time by half. VAS

acquisition starts after Address 17 is programmed (i.e.

rising edge of CSB), it takes the worst-case 896µs to

acquire lock.

Wireless LAN or MAN systems do not switch channel

frequency often, die temperature may change quite a bit

over time and makes PLL out of lock. To relock PLL as

soon as possible, the user can program Address 22 D<1>

= 1 after the first power-up frequency acquisition. VAS

starts from the previous frequency subband and should

relock PLL within 112µs.

VAS Readout

The selected VCO subband, Vtune ADC output and VAS

accomplished (VASA) signal can be read out through

DOUT pin by programming Address 9 D<7:5> = 010 and

corresponding Address 26 D<9:6>.

VCO Subband Selection Through SPI

For very fast band selection operation, the user can

characterize the mapping between VCO frequencies and

corresponding subbands during factory calibration. After

programming Address 22 D<0> = 0, the VCO subband

can be selected by Address 23 D<4:0>.

Programmable Registers

and 4-Wire SPI Interface

The MAX2837 includes 32 programmable 16-bit registers.

The most significant bit (MSB) is the read/write selection

bit. The next 5 bits are register address. The 10 least

significant bits (LSBs) are register data. Register data is

loaded through the 4-wire SPI/MICROWIRE®-compatible

serial interface. Data at DIN is shifted in MSB first and is

framed by CS. When CS is low, the clock is active, and

input data is shifted at the rising edge of the clock. During

the read mode, register data selected by address bits is

shifted out to DOUT at the falling edges of the clock. At

the CS rising edge, the 10-bit data bits are latched into the

register selected by address bits. See Figure 1. The reg-

ister values are preserved in shutdown mode as long as

the power-supply voltage is maintained. However, every

time the power-supply voltage is turned on, the registers

are reset to the default values. Note that default register

states are not guaranteed, and the user should always

reprogram all registers after power-up.

MICROWIRE is a registered trademark of National Semiconductor Corp.

www.maximintegrated.com

Maxim Integrated │  17

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