Analog Devices Inc. LTC3632EDD#PBF

Overview

LTC3632EDD#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, synchronous step-down DC/DC converter with integrated high-side and low-side MOSFETs, delivering up to 20mA output current, operating from 4.5V to 50V input, and maintaining regulation with only 12µA quiescent current in Burst Mode® operation - ideal for industrial control supplies and battery-operated devices requiring ultra-low standby power.

For engineers reviewing the LTC3632EDD#PBF datasheet, LTC3632EDD#PBF pinout, LTC3632EDD#PBF application, or LTC3632EDD#PBF equivalent, key selection criteria include its programmable peak current limit (10–50mA), 0.8V ±1% feedback reference, internal soft-start, precise RUN pin threshold (1.21V rising), and robust 60V surge tolerance - all in a thermally enhanced 3mm × 3mm DFN package.

Technical Context

The LTC3632EDD#PBF implements a hysteretic Burst Mode® control architecture where the feedback comparator (trip at 0.8V, 5mV hysteresis) enables burst cycles only when VFB falls below 0.795V, minimizing average supply current at light loads. Its peak current comparator is programmable via ISET pin (1µA source), allowing optimization of inductor size and efficiency across load ranges.

Startup is managed by a precision RUN pin comparator (1.21V rising threshold, 110mV hysteresis) and dual soft-start: internal 0.75ms ramp plus external capacitor-based ramp on SS pin (5.5µA sourced). Input protection includes UVLO (4.15V rising) and OVLO (56V rising), both rated to sustain 60V transients without damage.

Key Specifications

Pinout & Package

The LTC3632EDD#PBF is housed in an 8-lead, 3mm × 3mm plastic DFN package with exposed thermal pad (Pin 9 = GND), optimized for high power density and thermal performance (θ_JA = 43°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage, low-I_Q step-down converter applications.

Compared with LTC3631EDD#PBF, the LTC3632EDD#PBF adds design flexibility via ISET and HYST pins; compared with MAX5033BASA+, it delivers superior light-load efficiency and lower BOM cost at the expense of output current headroom and absolute input voltage ceiling.

Availability

LTC3632EDD#PBF is available at Aetrix Electronics and suitable for industrial control supplies, 4–20mA current loops, portable instruments, and automotive power systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC3632EDD#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC3632EDD#PBF belongs to Linear's high-voltage monolithic DC/DC converter product line, designed specifically for space-constrained, low-power applications demanding wide input range, ultra-low quiescent current, and robust fault protection - such as sensor nodes, loop-powered devices, and distributed control systems.

FAQ

What is the maximum input voltage the LTC3632EDD#PBF can withstand without damage?

The LTC3632EDD#PBF has an absolute maximum VIN rating of 60V and includes integrated overvoltage lockout (OVLO) that disables switching above 56V (rising). It can safely sustain 60V transients - such as automotive load dump - without damage, provided external components (e.g., input capacitor voltage rating) are appropriately selected. This makes the LTC3632EDD#PBF suitable for harsh environments where voltage spikes are common.

How does the ISET pin on the LTC3632EDD#PBF affect output current capability?

The ISET pin on the LTC3632EDD#PBF programs the peak inductor current limit from 10mA (shorted to GND) to 50mA (floating), directly determining maximum average output current - which is capped at half the peak value (i.e., 5–25mA). For example, setting ISET for 20mA peak yields ~10mA max average output. This allows designers to match inductor and capacitor sizing to actual load requirements, improving efficiency and reducing solution size. The LTC3632EDD#PBF thus supports precise current tailoring without changing the IC itself.

Does the LTC3632EDD#PBF require external compensation components?

No, the LTC3632EDD#PBF uses a hysteretic Burst Mode® control architecture with internal compensation - eliminating the need for external compensation networks (e.g., Type II/III compensators). Its feedback loop relies on a fixed 0.8V reference and built-in hysteresis (5mV), enabling stable regulation with only two external resistors (for VOUT setting) and standard passive components (inductor, input/output capacitors). This simplifies design, reduces bill-of-materials, and improves reliability - a key advantage of the LTC3632EDD#PBF in compact, low-risk power solutions.

Can the LTC3632EDD#PBF operate with 100% duty cycle, and why does that matter?

Yes, the LTC3632EDD#PBF supports 100% duty cycle operation - meaning it can maintain regulation even when input voltage drops close to the output voltage (e.g., VIN = 3.6V → VOUT = 3.3V). This is enabled by its synchronous architecture and low dropout characteristics. It matters because it maximizes usable battery voltage range in portable instruments and extends runtime in brownout-prone industrial systems. Unlike many buck converters that drop out below VIN ≈ 1.2×VOUT, the LTC3632EDD#PBF continues regulating down to VIN = VOUT + ~0.3V, making it uniquely suited for energy-constrained applications.

What is the role of the HYST pin on the LTC3632EDD#PBF, and how is it used?

The HYST pin on the LTC3632EDD#PBF is an open-drain output pulled low when the RUN pin voltage falls below 1.10V (i.e., when the device is disabled). It is used to extend the effective hysteresis of the RUN comparator - for example, by connecting a resistor from VIN to HYST and another from HYST to RUN, forming a positive feedback network that increases the gap between turn-on and turn-off thresholds. This prevents oscillation during slow-rising input rails or noisy conditions. The HYST pin adds flexibility without requiring additional ICs, reinforcing the LTC3632EDD#PBF's suitability for robust, self-contained power management.