MICRF219A_15 datasheet(14/25 Pages) MICREL

14 / 25 page

Micrel, Inc.

MICRF219A

August 12, 2015

Revision 3.0

RadioTech@micrel.com or (408) 944-0800

Programming the device is accomplished by the use of

pins DO and SCLK. Normally, DO (Pin 10) is outputting

data and needs to switch to an input pin made by the

start sequence, as shown at Figure 7.

High at the SCLK pin tri-states the DO pin, enabling 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 programming data.

SCLK frequency should be greater than 5kHz to avoid

automatic reset from internal circuitry.

Figure 7. Serial Interface Start Sequence

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 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 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) are programmed as needed. It

is recommended that all parallel input pins (SEL0, SEL1,

and SQ) be kept high when using the serial interface.

After the programming bits are finished, a stop sequence

(as shown in Figure 8) is required to end the mode and

re-establish the DO pin as an output again. To do so, the

SCLK pin is kept high while the DO pin changes from

low to high, then low again, followed by the SCLK pin

made 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 pin

T6 > 0.1 us, SCLK high time

T7 > 0.1 us, SCLK low time

T2, T3, T4, T5, T8, T9, T10 > 0.1 us

Figure 8. Serial Interface Stop Sequence

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