ML2712CH Просмотр технического описания (PDF) - Micro Linear Corporation

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ML2712CH

2.4GHz RF Transceiver

Micro Linear Corporation 

PRELIMINARY

ML2712

CONTROL INTERFACES (CONTINUED)

Control Bits DAC, COM & DCE

The DAC and comparator may be used as a tracking ADC

circuit. In normal operation these circuits are available in

TRANSMIT, RECEIVE & STANDBY operating Modes.

However, independent control of the comparator and DAC

is available via control bits as shown in Table 9. There are

two other modes available to program the DAC. When

DCE in CONTROL WORD B is set to 0, EN is active and

DACEN is disabled. With DCE at 1 both the DACEN and

EN pins are active. DACEN and EN cannot be

simultaneously low. With DCE at 1 a rising edge on

DACEN will write data to the 8-bit DAC regardless of the

address data.

Control Bit in

CONTROL

WORD B

DAC COM

Circuits Enabled

1

1

DAC & Comparator on

(Default power up state)

0

1

DAC off, Comparator on

1

0

DAC on, Comparator off

0

0

DAC & Comparator off

Table 9. Control of ML2712 DAC & Comparator

Control Bits CI1, CI2, CI3, CI4

The PLLs each contain a charge pump. The magnitude of

the current in these pumps may be controlled as defined

in Table 10. The recommended values for best phase

detector performance are [CI1,CI2]=[1,0] or [1,1] and

[CI3,CI4] = [1,0] or [1,1].

Control Bit CAL

The ML2713 companion to the ML2712 contains self-

aligning filter and discriminator circuits. The alignment of

these circuits is designed to take place when the ML2712/

ML2713 chipset is in STANDBY Mode ( Table 1). Under

power up default conditions in STANDBY Mode the

ML2712 provides an 8 MHz calibration tone to the

ML2713 via the 2LO output (pins 2LO & 2LOB). This will

happen while the 1LO and 2LO local oscillators are phase

locking. However, the CAL tone may be disabled using

CONTROL WORD B (See Table 11).

Control Bit in CONTROL WORD B

CI1

CI2

CI3

CI4

0

0

x

x

0

1

x

x

1

0

x

x

1

1

x

x

x

x

0

0

x

x

0

1

x

x

1

0

x

x

1

1

Charge Pump Setting

1LO Charge pump current (mA) 2LO Charge pump current (mA)

0.25

x

0.5

x

1

x

2

x

x

0.25

x

0.5

x

1

x

2

Table 10. Charge Pump Currents

CAL bit in CONTROL

WORD B

Calibration Mode

0

Calibration output to 2LO disabled

1

Calibration tone to 2LO port enabled (Default

power up mode)

Table 11. Control of Calibration Tone Generation

WB bit in CONTROL

WORD B

Calibration Mode

1

Wideband PLL phase Dual PFD & XOR mode

0

Wideband PLL phase In XOR only mode

Table 12. Control of CalibrationTone Generation

16

PRELIMINARY DATASHEET January, 2000

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