If the customer does not use LD(pin#1), how he should treat LD pin?
- 10kohm Pull up?
- Connect to GND?
In the HMC-EVB, LD pin is pulled up by 1lohm.
Is this purpose turning on LED?
If Lock Detect (LD) functionality is not needed on the HMC698LP5 simply leave it disconnected. The lock detect output is an open collector configuration (see Pin Descriptions on page 6-6 of the datasheet); adding the 1kΩ pull-up resistor to Vcc enables the LD circuit and limits the current through the output transistor. If enabled, the 100Ω resistor (R12) shown in the applications circuit on page 6-9 of the datasheet is required in order to limit the surge current that appears on the LD pin during the first few pulses after phase lock is achieved. It also allows rapid discharging of the shunt capacitor when no longer locked. Select capacitor C10 based on the comparison frequency, desired average voltage and the desired lock time.
Thank you for your prompt answer!
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