Summary of LTC3895 – Step-down controller handles 150 V
The LTC3895 is a high-performance synchronous step-down DC/DC controller supporting VIN up to 140V (150V abs max) and VOUT 0.8V–60V. It features programmable 5V–10V gate drive (OPTI-DRIVE), low IQ (40μA), 100% duty cycle, no external bootstrap diode, phase-lockable and programmable frequency, selectable operating modes including Burst Mode, adjustable current limit, power-good monitor, and onboard or external DRVCC LDO. Available in a 38-lead TSSOP, it targets automotive, industrial, battery-powered, and telecom power systems.
Parts used in the LTC3895 Project:
- LTC3895 controller (38-lead TSSOP)
- N-channel synchronous power MOSFETs
- External resistors for output voltage programming
- Inductor for the step-down stage
- Input and output capacitors (various ESR)
- External NMOS LDO (optional for DRVCC)
- Onboard LDO components (internal to LTC3895)
- Bootstrap switch (integrated, no external diode required)
- Compensation network for OPTI-LOOP
- Power Good indicator circuitry
LTC3895 – 150V Low IQ, Synchronous Step-Down DC/DC Controller
Features
- Wide VIN Range: 4V to 140V (150V Abs Max)
- Wide Output Voltage Range: 0.8V to 60V
- Adjustable Gate Drive Level: 5V to 10V (OPTI-DRIVE)
- Low Operating IQ: 40μA (Shutdown = 10μA)
- 100% Duty Cycle Operation
- No External Bootstrap Diode Required
- Selectable Gate Drive UVLO Thresholds
- Onboard LDO or External NMOS LDO for DRVCC
- EXTVCC LDO Powers Drivers from VOUT
- Phase-Lockable Frequency (75kHz to 850kHz)
- Programmable Fixed Frequency (50kHz to 900kHz)
- Selectable Continuous, Pulse-Skipping or Low Ripple
- Burst Mode® Operation at Light Loads
- Adjustable Burst Clamp and Current Limit
- Adjustable or Fixed (5V/3.3V) Output Voltage
- Power Good Output Voltage Monitor
- Programmable Input Overvoltage Lockout
- 38-Lead TSSOP High Voltage Package
Typical Application
Description
The LTC®3895 is a high performance step-down switching regulator DC/DC controller that drives an all N-channel synchronous power MOSFET stage that can operate from input voltages up to 140V. A constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz.
The gate drive voltage can be programmed from 5V to 10V to allow the use of logic or standard-level FETs to maximize efficiency. An integrated switch in the top gate driver eliminates the need for an external bootstrap diode. An internal charge pump allows for 100% duty cycle operation.
The low 40μA no-load quiescent current extends operating run time in battery-powered systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3895 features a precision 0.8V reference and power good output indicator. The output voltage can be programmed between 0.8V to 60V using external resistors or pin-programmed for a fixed 5V or 3.3V.
Applications
- Automotive and Industrial Power Systems
- High Voltage Battery Operated Systems
- Telecommunications Power Systems
For More Details: LTC3895 – Step-down controller handles 150 V
- What input voltage range does the LTC3895 support?
The LTC3895 supports a VIN range of 4V to 140V (150V absolute maximum). - What output voltage range can be achieved with the LTC3895?
The output voltage can be programmed from 0.8V to 60V or pin-programmed to fixed 5V or 3.3V. - Can the LTC3895 operate at 100% duty cycle?
Yes, the LTC3895 supports 100% duty cycle operation aided by an internal charge pump. - Does the LTC3895 require an external bootstrap diode?
No, an integrated switch in the top gate driver eliminates the need for an external bootstrap diode. - What are the typical quiescent and shutdown currents?
The LTC3895 has a low operating IQ of 40 microamperes and a shutdown current of 10 microamperes. - How is the gate drive voltage set and what range is available?
The gate drive voltage is programmable via OPTI-DRIVE and can be set between 5V and 10V. - What frequency options are available for the LTC3895?
Frequency is programmable: fixed from 50kHz to 900kHz and phase-lockable from 75kHz to 850kHz. - Does the LTC3895 support light-load efficiency modes?
Yes, it supports Burst Mode operation, selectable continuous, pulse-skipping, or low ripple modes for light loads. - Is there onboard regulation for driver supply DRVCC?
Yes, the LTC3895 provides an onboard LDO or can use an external NMOS LDO for DRVCC; EXTVCC LDO can power drivers from VOUT. - What applications is the LTC3895 targeted for?
It is targeted for automotive and industrial power systems, high voltage battery-operated systems, and telecommunications power systems.
