While many major brokers are permitting 100% of pledged margins for taking positions in intraday/options/and futures, Zerodha is insisting on 50% cash and 50% collateral. At least for clients with good track record and years of dealing, they should give this facility. Pledged margins of liquid stocks are equal to cash margin. After all, clients buy this by paying cash only. Even well-known brokers are permitting cash buying of stocks against collateral/pledged margin.
FYI, you can find Zerodha’s stand on this topic
in various threads in this forum
by searching for “50% cash and 50% collateral”
Linking the topic-threads below for quick reference…