Analog Devices Inc. LTC2938IMS#TRPBF

Overview

LTC2938IMS#TRPBF from Analog Devices (formerly Linear Technology) is a configurable 4-supply voltage monitor IC with integrated watchdog timer, reset output, and programmable threshold selection via external resistive divider. It monitors up to four independent supply rails (e.g., 5V, 3.3V, 2.5V, 1.8V), provides ±1.5% threshold accuracy over temperature, supports adjustable reset and watchdog timeout periods using external capacitors, and operates down to VCC = 1V - enabling reliable power-up/power-down supervision in multivoltage embedded systems.

For engineers reviewing the LTC2938IMS#TRPBF datasheet, LTC2938IMS#TRPBF pinout, LTC2938IMS#TRPBF application, or LTC2938IMS#TRPBF equivalent, key selection considerations include its 12-lead MSOP package, –40°C to +85°C industrial temperature grade, 80μA typical supply current, guaranteed RST assertion below 1V VCC, and support for both positive and negative adjustable thresholds on V3/V4 inputs.

Technical Context

The LTC2938IMS#TRPBF implements six high-impedance comparator inputs (V1–V4) with factory-preset and user-programmable thresholds (5V/3.3V/2.5V/1.8V/1.5V/1.2V or ADJ/–ADJ), where V1 and V2 serve as internal supply (VCC) and reference sources. Its configuration logic samples VPG during a 150μs power-up window to select one of sixteen voltage combinations, while internal bandgap reference (1.210V ±1.5%) ensures stable threshold generation across temperature.

Reset timing (tRST = 2–4ms/nF on CRT) and watchdog timeout (tWD = 20–40ms/nF on CWT) are independently set by external capacitors; both outputs (RST and WDO) feature weak 6μA pull-ups to V2 and support external pull-up to higher voltages. Glitch immunity is built-in, and RST remains valid down to VCC = 1V - critical for brownout detection in low-voltage microcontroller systems.

Key Specifications

Pinout & Package

Package: 12-Lead Plastic MSOP (3mm × 3mm), exposed pad optional, θJA = 130°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6324US29D3+T and TPS3808G33DBVR, the LTC2938IMS#TRPBF delivers unique value through its 4-rail configurability, integrated watchdog, and ±1.5% accuracy - making it irreplaceable in systems requiring coordinated power validation and firmware supervision.

Availability

LTC2938IMS#TRPBF is available at Aetrix Electronics and suitable for desktop computers, telecom equipment, and automotive control systems requiring stable component supply, industrial temperature operation, and long-term production continuity.

Supply support for LTC2938IMS#TRPBF 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, serving industrial, automotive, communications, and healthcare markets.

The LTC2938IMS#TRPBF belongs to ADI's Linear Technology legacy supervisor IC portfolio, designed specifically for multivoltage system power integrity - emphasizing precision thresholding, low quiescent current, and robust fault detection in space-constrained embedded platforms.

FAQ

What is the operating temperature range for the LTC2938IMS#TRPBF?

The LTC2938IMS#TRPBF is rated for –40°C to +85°C operation, qualifying it for industrial and extended-temperature embedded applications. This grade is explicitly defined in the order information table for the IMS package variant, and thermal performance data (e.g., θJA = 130°C/W) confirms suitability for convection-cooled MSOP layouts in demanding environments.

How do I configure the LTC2938IMS#TRPBF to monitor 5V, 3.3V, 2.5V, and 1.8V rails?

To configure the LTC2938IMS#TRPBF for 5V/3.3V/2.5V/1.8V monitoring, connect a resistive divider between VREF (Pin 5) and GND (Pin 6) with R1 = 66.5kΩ and R2 = 34.8kΩ (1% tolerance), then tie the divider midpoint to VPG (Pin 4). This sets VPG/VREF ≈ 0.344, selecting Mode 5 per Table 1 - enabling simultaneous monitoring of those four rails with ±1.5% threshold accuracy.

Can the LTC2938IMS#TRPBF monitor a negative supply rail?

Yes - the LTC2938IMS#TRPBF supports negative rail monitoring on V4 using the –ADJ mode. In this configuration, connect the negative supply to one end of an external resistor divider, tie the other end to VREF (1.210V), and connect the divider tap to V4. The internal comparator references VREF, enabling accurate trip-point setting (e.g., –1.87V with R3 = 1.87kΩ, R4 = 121kΩ) as specified in Table 3.

What happens to the RST output when VCC drops below 1V?

The RST output of the LTC2938IMS#TRPBF is guaranteed to remain in the correct logic-low state down to VCC = 1V. Below 1V, internal circuitry ceases operation and RST behavior is no longer specified - however, the guaranteed low state above 1V ensures clean reset assertion through the critical brownout region where most MCUs lose functional integrity.

Is an external pull-up resistor required on the RST pin when monitoring a 1.8V supply on V2?

Yes - when V2 is configured to monitor 1.8V (or any supply ≤2.5V), the internal 6μA pull-up to V2 cannot ensure RST VOH exceeds typical VIH thresholds (e.g., 2.0V for 3.3V logic). An external pull-up resistor from RST to the target interface supply (e.g., 3.3V) is required to guarantee proper logic-high signaling and avoid metastability in downstream circuits.