HMC701LP6CE Datasheet, PDF (33/46 Pages) Hittite Microwave Corporation – 8 GHz 16-Bit Fractional-N Synthesizer

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HMC701LP6CE
8 GHz 16-Bit Fractional-N Synthesizer
11
Main Serial Port READ Operation
The synthesizer uses the multi-purpose pin, LD_SDO, for both Lock Detect and Serial Data Out (SDO) functions. The
registers lkd_to_sdo_automux_en (Reg1A<12>) and lkd_to_sdo_always (Reg1A<13> Table 36) determine how the
Data Output pin is muxed with the Lock Detect function. If both of the registers are cleared, then the pin is exclusively
SDO. If automux is enabled, the pin switches to SDO when the RD function is sensed on the 1st rising edge of SCLK.
If lkd_to_sdo_always is set, then the pin LD_SDO is dedicated for Lock Detect only, and it is not possible to read from
the synthesizer.
A typical READ cycle is shown in Figure 30.
a. The Master (host) asserts both SEN (Serial Port Enable) and SDI to indicate a READ
cycle, followed by a rising edge SCLK
b. The slave (synthesizer) reads SDI on the 1st rising edge of SCLK after SEN. SDI high initiates
the READ cycle (RD)
c. Host places the six address bits on the next six falling edges of SCLK, MSB first.
d. Slave registers the address bits on the next six rising edges of SCLK (2-7).
e. Slave places the 24 data bits on the next 24 rising edges of SCK (8-31), MSB first .
f. Host registers the data bits on the next 24 falling edges of SCK (8-31).
g. SEN is de-asserted on the 32nd falling edge of SCLK.
h. The 32nd falling edge of SCLK completes the cycle
11 - 34
Figure 30. Serial Port Timing Diagram - READ
VCO SERIAL PORT
The VCO Serial Port is a 3-wire serial port that may be used to control external step tuned VCOs that support serial
port control. Visit the Hittite website or contact Hittite Sales for a full list of compatible VCOs. The VCO Serial Port is
a 3-wire serial port that may be used to control external step tuned VCOs that support serial port control. The 3-wire
VCO serial port uses the following pins, as shown in Figure 31:
VSDO: VCO Serial Port Data Out
VSCK: VCO Serial Port Clock
VSLE: VCO Serial Port Latch Enable
The VCO Serial Port transfers the contents of the 16-bit register spivco_direct_data (Reg0Bh Table 22) to the VCO
upon receipt of a frequency change command. The lsbs of spivco_direct_data are the switch settings for the VCO and
may be set directly or by the autotune routine described in the section Step Tuned VCO Support. Multiple VCO formats
are supported for autotuning. VCO tuning bits are configured with sar_bits_number (Reg0Dh<5:4> Table 24). Multiple
VCO SPI formats are also supported and are configured by spivco_mode (Reg0Dh<1:0> Table 24).
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20 Alpha Road, Chelmsford, MA 01824 Phone: [phone] Fax: [phone]
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