Analog Devices Inc. LTC2900-1IMS#PBF

Overview

LTC2900-1IMS#PBF from Analog Devices (acquired Linear Technology) is a programmable quad supply monitor IC with open-drain RST output, simultaneously monitoring up to four independent voltage rails (e.g., 5V, 3.3V, 2.5V, 1.8V), ±1.5% threshold accuracy over temperature, 43µA typical supply current, and adjustable reset timeout via external capacitor. It serves as a system-level power integrity guardian in multivoltage embedded controllers.

For engineers reviewing the LTC2900-1IMS#PBF datasheet, LTC2900-1IMS#PBF pinout, LTC2900-1IMS#PBF application, or LTC2900-1IMS#PBF equivalent, key selection criteria include guaranteed RST assertion down to VCC = 1V, manual reset input (PBR) with debounced timing, 16-programmable voltage threshold combinations, and compatibility with MSOP-10 and DFN-10 packages for space-constrained PCBs.

Technical Context

The LTC2900-1IMS#PBF implements four independent high-accuracy comparators referenced to a buffered 1.210V internal bandgap, each configurable via external resistor divider on VPG to select preset or adjustable thresholds. Its architecture guarantees glitch immunity and correct RST state during brownout, power-up, and power-down sequences.

Reset timing is controlled by an external capacitor on CRT pin (4.6ms/nF scaling), while the open-drain RST output pulls low when any monitored rail falls below its threshold and remains asserted for the programmed delay after all rails recover. The manual reset pin (PBR) provides hardware-initiated reset pulses with identical timing behavior.

Key Specifications

Pinout & Package

Package: 10-lead MSOP (3mm × 3mm footprint, 0.5mm pitch, exposed pad). Compatible with standard reflow profiles and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC2901CMS#PBF, LTC2900-1IMS#PBF trades watchdog capability for 30% smaller MSOP-10 footprint and eliminates redundant timing circuitry; versus LTC1326CS8#PBF, it adds a fourth rail, manual reset, and programmable timeout at the cost of slightly relaxed accuracy (±1.5% vs ±0.75%).

Availability

LTC2900-1IMS#PBF is available at Aetrix Electronics and suitable for desktop computers, telecom equipment, and network servers requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for LTC2900-1IMS#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. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies.

The LTC2900 family was designed by Linear Technology (now part of ADI) specifically for precision multivoltage system supervision in computing, communications, and industrial infrastructure-emphasizing low power, configurability, and robustness under brownout conditions.

FAQ

What is the minimum VCC voltage that guarantees correct RST logic state for LTC2900-1IMS#PBF?

The LTC2900-1IMS#PBF guarantees correct RST logic state (active-low assertion) for VCC ≥ 1V. This specification ensures reliable reset generation during deep brownout events before the internal bandgap reference collapses, making LTC2900-1IMS#PBF suitable for systems requiring fail-safe power monitoring down to near-zero supply conditions.

How does the CRT capacitor value determine the reset timeout period for LTC2900-1IMS#PBF?

The CRT capacitor sets the reset timeout period (tRST) linearly: tRST ≈ CRT × 217 × 10⁻⁹ seconds, or equivalently 217 pF per millisecond. For example, a 47nF capacitor yields tRST ≈ 216ms. Leaving CRT unconnected produces a minimum ~50µs delay. Leakage and tolerance of the capacitor directly impact timing accuracy, so low-leakage ceramic types are recommended for LTC2900-1IMS#PBF.

Can LTC2900-1IMS#PBF monitor negative voltage rails, and if so, how is it implemented?

Yes, LTC2900-1IMS#PBF supports negative rail monitoring via its V4 pin in –ADJ mode. In this configuration, an external resistor divider connects between the negative supply and VREF (1.210V), with the tap point fed to V4. The internal comparator references VREF to generate a trip point such as –4.64V. This method leverages VREF as a level-shift reference, enabling accurate detection without external op-amps or charge pumps for LTC2900-1IMS#PBF.

What is the function of the VPG pin on LTC2900-1IMS#PBF, and what happens if it is left floating?

The VPG pin selects one of 16 voltage threshold combinations via a resistive divider between VREF and GND. If left floating, LTC2900-1IMS#PBF defaults to Mode 0 (5V/3.3V/ADJ/ADJ), but operation is not guaranteed-Linear Technology specifies that VPG must be actively driven within 0V to VREF during the ~150µs programming window after VCC rise. Floating VPG risks incorrect configuration or undefined behavior, so proper 1% resistor termination is mandatory for reliable LTC2900-1IMS#PBF operation.

How does the open-drain RST output of LTC2900-1IMS#PBF differ from the push-pull RST of LTC2900-2IMS#PBF in practical circuit design?

The LTC2900-1IMS#PBF RST output is open-drain with a weak internal pull-up (~6µA to V2), requiring an external pull-up resistor for defined VOH and faster rise times. In contrast, LTC2900-2IMS#PBF provides active push-pull drive (200µA source) eliminating external components. Designers choosing LTC2900-1IMS#PBF gain flexibility in setting VOH above V2 (e.g., to 5V logic) but must account for slower rise time unless external pull-up is added.