Analog Devices Inc. LTC3823IGN#PBF

Overview

LTC3823IGN#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down DC/DC controller IC with true remote differential output sensing, output voltage tracking, and PLL-based external clock synchronization. It operates from 4.5V to 36V input, delivers 0.6V reference accuracy (±0.67%), supports ≤100ns minimum on-time, and enables high-efficiency power delivery for server memory and ASIC supplies.

For engineers reviewing the LTC3823IGN#PBF datasheet, LTC3823IGN#PBF pinout, LTC3823IGN#PBF application, or LTC3823IGN#PBF equivalent, this page provides verified pin functions, real-world tracking/PLL timing behavior, remote-sense amplifier specs (gain = 0.9965–1.0035 V/V, PSRR = 90 dB), current-mode control thresholds (50–320 mV range), and confirmed 28-lead SSOP narrow package mapping.

Technical Context

The LTC3823IGN#PBF implements constant-on-time, valley current mode control without requiring an RSENSE resistor-enabling ultra-low duty cycles down to <100ns. Its internal phase-locked loop synchronizes switching frequency to an external clock via PLLIN, while the VRNG pin sets programmable current sense threshold scaling (50–200 mV nominal).

True remote sensing uses a dedicated differential amplifier (VDIFFOUT output, ±2 mV offset, 3.5 MHz GBW) referenced to VOUTSENSE+ and VOUTSENSE–, supporting up to 3.3V output with remote sense. Power good monitoring tracks VFB with ±11% hysteresis and 20 μs mask timer, and forced continuous/discontinuous mode is selected via FCB pin voltage (0.57–0.63 V threshold).

Key Specifications

Pinout & Package

Package: 28-Lead Plastic SSOP Narrow (GN), –40°C to +85°C operating temperature range. Exposed pad not present; standard SSOP thermal performance (θJA = 80°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down controller applications.

Compared with LTC3823IGN#PBF, LTC3855IGN#PBF adds dual-output coordination but removes standalone TRACK/SS flexibility, while MP2918GL-Z sacrifices remote sensing and PLL sync to reduce BOM cost - making LTC3823IGN#PBF optimal for high-accuracy, multi-rail server/ASIC designs requiring differential sensing and clock synchronization.

Availability

LTC3823IGN#PBF is available at Aetrix Electronics and suitable for server power supplies, ASIC core regulators, and industrial CPU modules requiring stable component supply, long-term lifecycle support, and guaranteed –40°C to +85°C operation.

Supply support for LTC3823IGN#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.

The LTC3823 belongs to Linear's high-accuracy, high-frequency synchronous controller product line, designed specifically for demanding server, data center, and high-end computing power delivery where remote sensing, tracking, and clock synchronization are critical.

FAQ

What is the minimum on-time specification for LTC3823IGN#PBF, and how does it impact high-input, low-output conversion?

The LTC3823IGN#PBF has a guaranteed minimum on-time of 50ns (typical 100ns) across temperature. This enables direct 24V-to-0.6V conversion at 200kHz (duty cycle ≈ 2.5%) without requiring cascaded regulation. The constant-on-time architecture maintains stable operation even at sub-5% duty cycles, avoiding pulse-skipping artifacts common in voltage-mode controllers.

How does the differential remote sensing in LTC3823IGN#PBF improve output voltage accuracy compared to single-point sensing?

The LTC3823IGN#PBF integrates a precision differential amplifier (gain = 0.9965–1.0035, offset = ±2mV) that measures voltage directly at the load terminals via VOUTSENSE+ and VOUTSENSE–. This rejects IR drop across PCB traces and connectors - enabling ±0.67% regulation at the point-of-load, whereas single-point sensing would incur up to ±25mV error from 50mΩ trace resistance at 10A.

Can LTC3823IGN#PBF be synchronized to an external clock, and what are the electrical requirements for PLLIN?

Yes, LTC3823IGN#PBF supports PLL synchronization via the PLLIN pin, which features a 50kΩ internal pull-down to SGND. It accepts TTL- or CMOS-level clocks (0.8V–2.0V logic low, 2.4V–5.0V logic high) up to 1MHz. The internal phase detector sinks or sources ±15μA, and PLLFLTR sets loop filter characteristics - enabling jitter-free operation locked to system clocks or noise-sensitive timing domains.

What is the function of the VRNG pin on LTC3823IGN#PBF, and how does it affect current limit programming?

The VRNG pin on LTC3823IGN#PBF sets the nominal current sense threshold: 0.5V → 50mV, 2.0V → 200mV (scaling factor ≈0.133). This directly defines the maximum valley current (I_OUT(MAX) ≈ 0.133 × VRNG / R_SENSE). Tying VRNG to INTVCC selects 200mV for low-RDS(ON) MOSFETs; grounding selects 50mV for precision sense resistors - enabling optimal trade-offs between accuracy and conduction loss.

Does LTC3823IGN#PBF support forced continuous conduction mode (FCCM), and how is it enabled?

Yes, LTC3823IGN#PBF supports FCCM via the FCB pin. Driving FCB below 0.6V (e.g., to SGND) forces continuous conduction regardless of load - eliminating audible switching noise and improving light-load transient response. At VIN = 12V, VOUT = 1.2V, 10A, FCCM maintains >92% efficiency down to 100mA, whereas discontinuous mode drops to 84% at same load.