Analog Devices Inc. LTC3633AEFE-2#PBF

Overview

LTC3633AEFE-2#PBF from Analog Devices (formerly Linear Technology) is a dual-channel monolithic synchronous step-down regulator delivering 3A per channel across a 3.6V–20V input range. It features current-mode control, selectable 0°/180° phase shift between channels, and supports output voltages from 0.6V to 6V using its internal 0.6V reference. It is used in point-of-load power supplies for FPGA, ASIC, and DSP core rails where high efficiency, fast transient response, and compact layout are critical.

For engineers reviewing the LTC3633AEFE-2#PBF datasheet, LTC3633AEFE-2#PBF pinout, LTC3633AEFE-2#PBF application, or LTC3633AEFE-2#PBF equivalent, key selection considerations include its 500kHz–4MHz adjustable switching frequency, Burst Mode® vs forced continuous operation modes, dual-channel out-of-phase capability for reduced input ripple, and TSSOP-28 package thermal performance (θ_JA = 25°C/W).

Technical Context

The LTC3633AEFE-2#PBF implements a controlled on-time, current-mode architecture with an internal phase-locked loop that locks switching frequency to either an internal oscillator (set by RT resistor or INTVCC default) or external clock applied to MODE/SYNC. Its dual independent buck channels share no power stage but synchronize timing via PLL and support 180° phase shift via PHMODE pin to reduce input capacitor RMS current.

Each channel uses internal N-channel MOSFETs (130mΩ top / 65mΩ bottom), senses valley inductor current via PGND-SW voltage drop, and regulates output by adjusting ITH voltage to maintain VFB at 0.6V. The VON1/VON2 pins enable VOUT-proportional on-time for stable operation across wide output voltage ranges (0.6V–6V for LTC3633A-2 variant).

Key Specifications

Pinout & Package

The LTC3633AEFE-2#PBF is housed in a 28-lead plastic TSSOP package (JEDEC MO-153) with exposed PGND pad for thermal and electrical integrity. Pin pitch is 0.65mm; package dimensions are standard TSSOP footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel synchronous buck regulator applications.

Compared with MP2491DS-LF-Z, the LTC3633AEFE-2#PBF delivers dual independent rails, phase control, and intelligent light-load management - essential for complex SoC power trees. Versus LTC3633AEUFD-2#PBF, the TSSOP version offers superior thermal resistance (25°C/W) in airflow-limited environments but occupies larger PCB area.

Availability

LTC3633AEFE-2#PBF is available at Aetrix Electronics and suitable for FPGA core power, industrial PLC I/O modules, and battery-powered test instruments requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for LTC3633AEFE-2#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for all Linear-branded power ICs including the LTC3633A family.

The LTC3633A series was designed for high-density, high-efficiency dual-rail point-of-load conversion in FPGA, ASIC, and DSP applications - emphasizing fast transient response, flexible sequencing, and robust protection in harsh environments.

FAQ

What is the maximum input voltage rating for LTC3633AEFE-2#PBF?

The LTC3633AEFE-2#PBF has an absolute maximum PVIN rating of 20V, with overvoltage lockout triggered at 22.5V (rising) and released at 21.5V (falling). This protects internal MOSFETs during transient spikes. Operation above 20V violates the recommended operating conditions and may cause permanent damage. Always ensure input filtering and clamping are sized for worst-case surge events in the target application.

Does LTC3633AEFE-2#PBF support output voltage tracking between channels?

Yes, the LTC3633AEFE-2#PBF supports precise output voltage tracking via the TRACKSS1 and TRACKSS2 pins. Applying a common ramp voltage (e.g., from an external DAC or RC network) below 0.6V to both pins forces each channel's FB node to servo to that voltage, enabling synchronized startup and dynamic voltage scaling. Internal 1.4µA pull-up current enables simple capacitor-based soft-start with 400–700µs rise time.

How does the phase shift function work on LTC3633AEFE-2#PBF?

The LTC3633AEFE-2#PBF uses the PHMODE pin to select channel phasing: grounding PHMODE enables in-phase switching, while tying it to INTVCC forces 180° out-of-phase operation. This interleaving reduces input capacitor RMS current by up to 30%, lowers EMI, and eases thermal design. The phase relationship is maintained across all operating modes (Burst/continuous) and frequencies (500kHz–4MHz).

Can LTC3633AEFE-2#PBF operate with only one channel enabled?

Yes, the LTC3633AEFE-2#PBF supports independent channel control. Driving RUN1 high enables Channel 1 while holding RUN2 low disables Channel 2 - and vice versa. Both channels share SVIN and INTVCC but have separate PVIN, SW, BOOST, and feedback paths. Disabling a channel reduces quiescent current to <13µA per disabled channel, making it suitable for partial-power modes.

What is the purpose of the VON1 and VON2 pins on LTC3633AEFE-2#PBF?

The VON1 and VON2 pins set the on-time comparator threshold for each channel. Tying VONx to VOUTx makes on-time proportional to output voltage - ensuring constant frequency and stable operation across the full 0.6V–6V output range (LTC3633A-2 specification). This eliminates frequency droop at low VOUT and supports high step-down ratios (e.g., 12V→0.6V) without compromising regulation accuracy.