Analog Devices Inc. LTC2901-1CGN

Overview

LTC2901-1CGN from Analog Devices (formerly Linear Technology) is a programmable quad supply monitor IC with open-drain RST output, designed to simultaneously supervise four independent voltage rails (e.g., 5V, 3.3V, 2.5V, 1.8V) in multivoltage systems. It features ±1.5% threshold accuracy over temperature, 43μA typical supply current, adjustable reset delay via CRT capacitor, and guaranteed RST assertion down to VCC ≥ 1V. It is used in desktop computers, telecom equipment, and network servers for reliable power-on reset and brownout detection.

For engineers reviewing the LTC2901-1CGN datasheet, LTC2901-1CGN pinout, LTC2901-1CGN application, or LTC2901-1CGN equivalent, key selection criteria include its 16-pin narrow SSOP package, open-drain RST output topology, 5% or 10% undervoltage tolerance (via external TOL logic on compatible variants), individual nondelayed comparator outputs (COMP1–COMP4), and compatibility with adjustable ±ADJ monitoring configurations.

Technical Context

The LTC2901-1CGN implements four independent high-accuracy voltage comparators referenced to a buffered 1.210V internal bandgap, with thresholds selected via a 1% resistive divider on VPG. Its reset timing is controlled by an external capacitor on CRT (4.6 ms/nF scaling), while watchdog timeout (on WDI/WDO) uses CWT (20 ms/nF). The device guarantees correct RST logic state for VCC ≥ 1V and exhibits glitch immunity during supply transients.

All comparator outputs (COMP1–COMP4) are active-high, nondelayed, and weakly pulled up to V2; RST is open-drain with weak pull-up to V2 (LTC2901-1/LTC2901-3 only). Input voltage ranges span –0.3V to 7V per pin, and reference load capability is ±1mA on VREF. Programming occurs once during power-up when VCC exceeds 2.42V.

Key Specifications

Pinout & Package

Package: 16-lead plastic narrow SSOP (GN16), 0.15 mm lead thickness, 0.65 mm pitch, JEDEC MO-178AC compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad supply monitoring applications.

Compared with LTC2901-2CGN, the LTC2901-1CGN offers lower external component count for open-drain bus interfacing but requires an external pull-up; compared with TPS3808G33DBVR, it provides full quad monitoring, programmable thresholds, and independent comparator outputs - making it suitable for complex multivoltage systems where flexibility and diagnostics are essential.

Availability

LTC2901-1CGN is available at Aetrix Electronics and suitable for desktop computers, telecom equipment, and network servers requiring stable component supply across extended production lifecycles.

Supply support for LTC2901-1CGN 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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, acquired Linear Technology in 2017 to expand precision power and monitoring solutions.

The LTC2901 product line delivers programmable multirail supervision ICs optimized for reliability-critical applications in computing, communications, and industrial infrastructure - emphasizing accuracy, low power, and flexible configuration.

FAQ

What is the function of the VPG pin on the LTC2901-1CGN?

The VPG pin on the LTC2901-1CGN accepts a voltage divider tap between VREF and GND to select one of 16 predefined voltage threshold combinations for V1–V4. During power-up, when VCC exceeds 2.42V, the device samples VPG and configures its internal comparators accordingly. No capacitance should be added to VPG to avoid programming errors, and 1% resistors are recommended for accuracy. This single-pin programming eliminates the need for multiple fixed-threshold supervisors.

How does the LTC2901-1CGN guarantee reset assertion during brownout?

The LTC2901-1CGN guarantees correct RST logic state for VCC ≥ 1V, meaning it asserts RST low reliably even as supply voltage drops below normal operating levels. Its internal comparators remain functional down to this threshold, and the open-drain RST output maintains defined behavior due to weak internal pull-up to V2. This ensures deterministic reset during brownout and power-down sequences, preventing undefined processor states in systems like network servers and telecom line cards.

Can the LTC2901-1CGN monitor negative voltages?

Yes, the LTC2901-1CGN supports negative voltage monitoring in –ADJ mode on V4. In this configuration, the noninverting input of the V4 comparator connects to ground, and an external resistor divider between the negative supply and VREF (1.210V) sets the trip point. The formula is VTRIP = VREF × R3/(R3 + R4), enabling accurate supervision of rails such as –5V or –12V. Minimum R4 is constrained by VREF's ±1mA sourcing capability, e.g., ≥1.21kΩ for –5V sensing.

What is the maximum recommended value for the CRT capacitor on the LTC2901-1CGN?

The CRT capacitor on the LTC2901-1CGN has no absolute maximum value specified, but practical limits arise from capacitor leakage and tolerance. The internal charging current is ~2μA, so high-leakage capacitors (e.g., electrolytic or certain ceramics) degrade timing accuracy. For stable operation beyond ~1 second reset delay, low-leakage film or Class I ceramic capacitors (e.g., C0G/NP0) are recommended. A 10μF CRT yields ~4.6 s delay; larger values increase risk of drift due to leakage-induced voltage error.

Does the LTC2901-1CGN include watchdog functionality, and how is it implemented?

Yes, the LTC2901-1CGN includes a configurable watchdog timer. It monitors edges on the WDI pin and asserts WDO low if no edge occurs within the timeout period set by the CWT capacitor (tWD = 20 ms/nF). WDO remains low until the next WDI edge or until RST goes low. Unlike LTC2901-3/4 variants, the LTC2901-1CGN uses a dedicated WDO pin rather than merging watchdog action into RST - enabling separate fault handling for software hangs versus power faults.