The constant frequency current mode architecture provides a fixed operating frequency of 400kHz. The ltc3854 has an on-chip 5V regulator, which eliminates the need for an independent bias voltage to power the chip. OPTI-LOOP ® Compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values, including all ceramic capacitor design. Output current detection measures the voltage drop across the output inductor (DCR) or an optional detection resistor. In the case of short circuit and overload, the current turn back limits the thermal dissipation of MOSFET. In addition, the ltc3854 has an adjustable soft start to control the on time and control the surge current. The optional continuous or intermittent inductor current mode can be used to safely power the pre biased load. The anti through protection prevents the through current in the power MOSFET. The ltc3854 operates at a duty cycle of up to 96% and has a very low differential voltage to extend the operating time of battery powered applications. The ltc3854 has an accurate 0.8V reference with an accuracy of ± 1% in the operating temperature range of – 40 º C to 85 º C.

Performance characteristics and application of Synchronous Step-Down Switching DC / DC controller ltc3854

Performance summary: ltc3854

Vin range: 4V to 38V

Vout range: 0.8V to 5.5V

Powerful on-chip n-channel MOSFET Driver

Built in 5V voltage regulator

Small 2mmx3mm dfn-12 package

Anti penetration protection

Current mode control

Safely power the pre biased load

DCR or RSENSE current detection option

Output turn back current limit

Programmable soft start

40KHz fixed operating frequency

96% maximum duty cycle

± 1% reference voltage accuracy in the temperature range of – 40 º C to + 85 º C

Responsible editor: GT

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