MICRF219 datasheet(17/24 Pages) MICREL

17 / 24 page

Micrel

MICRF219

ycle,

Figure 12. Time-to-Good-Data After Shut Do

315MHz at Room Temperat

wn C

ure.

y th

inp

igure

High at the SCLK pin tri-states the DO pin, en bling

the external drive into the DO pin with an initial low

level. The start sequence is completed by taking

SCLK low, then high while DO is low, followed by

taking DO high, then low while SCLK is high. The

serial interface is initialized and ready to receive the

Serial Register Programming

Programming the device is accomplished b

of pins DO and SCLK. Normally, D0 (P

outputting data and needs to switch to an

made by the start sequence, as shown at F

January 2009

M9999-011509

(408) 944-0800

e u

10) is

ut pin

13.

programming data.

BIT TIME 1

BIT TIME 0

DO AS

OUTPUT

DO INPUT BITS:

D19

“19”

“0”

D18

SCLK

“1”

BIT TIME 2

nce.

Bits are serially programmed starting with the most

significant bit (MSB = D19) if all bits are being

programmed until the least significant bit (LSB =D0)

For instance, if only the desense bits D0, D1, and D2

are being programmed, then these are the only bits

that need to be programmed with the start sequence

D2, D1, D0, plus the stop sequence. Or, if only the

squelch bit D17 is needed, then the sequence must

be from start sequence, D17 through D0 plus the stop

sequence, making sure the other bits (besides D17)

is recommended that

EL1, and SQ) be kept

interface. After the

, a stop sequence (as

d the mode and

reestablish the DO pin as an output again. To do so,

pin is kept high while the DO pin changes

to high, then low again, followed by the

low. Timing of the programming bits

are not critical, but should be kept as shown below:

T1 < 0.1 us, Time from SCLK to convert DO to input

T6 > 0.1 us, SCLK high time

T7 > 0.1 us, SCLK low time

.1 us

Figure 13. Serial Interface Start Seque

are programmed as needed. It

all parallel input pins (SEL0, S

high when using the serial

programming bits are finished

shown in Figure 14) is required to en

the SCLK

from low

SCLK pin made

T2, T3, T4, T5, T8, T9, T10 > 0

DO PIN AS OUTPUT

“1”

“0”

“1”

SCLK

T10

BIT TIME 18

BIT TIME 19

Figure 14. Serial Interface Stop Sequence.

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