ZHCSIJ1E June 1999 – July 2018 LM2574 , LM2574HV
PRODUCTION DATA.
For normal operation, the ON/OFF pin must be grounded or driven with a low-level TTL voltage (typically less than 1.6 V). To put the regulator into standby mode, drive this pin with a high-level TTL or CMOS signal. The ON/OFF pin can be safely pulled up to +VIN without a resistor in series with it. The ON/OFF pin must not be left open.