Analog Devices Inc. LTC2900-2CDD#PBF

Overview

LTC2900-2CDD#PBF from Analog Devices (acquired Linear Technology) is a programmable quad supply monitor IC with push-pull RST output, simultaneously monitoring four 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 supervisor in multivoltage embedded controllers.

For engineers reviewing the LTC2900-2CDD#PBF datasheet, LTC2900-2CDD#PBF pinout, LTC2900-2CDD#PBF application, or LTC2900-2CDD#PBF equivalent, key selection criteria include guaranteed RST validity down to VCC = 1V, push-pull output drive capability (200µA source), manual reset propagation delay <1µs, and support for both positive/negative adjustable thresholds via external resistor dividers.

Technical Context

The LTC2900-2CDD#PBF implements four independent high-accuracy comparators referenced to a buffered 1.210V internal bandgap, with threshold selection determined by a ratiometric voltage applied to the VPG pin. Its architecture guarantees glitch immunity and correct RST state during brownout conditions.

Unlike open-drain variants, the LTC2900-2CDD#PBF features an actively driven push-pull RST output tied to V2, enabling direct interface with CMOS logic without external pull-ups. Reset timing is set by CRT pin capacitance (217 pF/ms scaling), and manual reset is debounced through the same timing circuitry.

Key Specifications

Pinout & Package

Package: 10-lead 3mm × 3mm plastic DFN (exposed pad), RoHS-compliant, θJA = 43°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC2901CMS#PBF and LTC2902IMS#PBF, the LTC2900-2CDD#PBF delivers essential quad-supply monitoring in the smallest package (3mm × 3mm DFN) with lowest quiescent current (43µA), making it optimal for space- and power-constrained commercial applications where watchdog or margining features are unnecessary.

Availability

LTC2900-2CDD#PBF is available at Aetrix Electronics and suitable for desktop computers, telecom equipment, and network servers requiring stable component supply, precise multirail supervision, and RoHS-compliant packaging.

Supply support for LTC2900-2CDD#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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through acquisition of Linear Technology in 2017.

The LTC2900 family was designed by Linear Technology specifically for high-accuracy, low-power quad-supply monitoring in commercial multivoltage systems, emphasizing threshold stability, glitch immunity, and flexible configuration without external logic.

FAQ

What is the maximum reset timeout achievable with LTC2900-2CDD#PBF?

The LTC2900-2CDD#PBF reset timeout is set by the CRT capacitor value using the formula CRT = tRST × 217 × 10⁻⁹ (CRT in farads, tRST in seconds). With commercially available low-leakage ceramic capacitors up to 10µF, timeouts exceeding 10 seconds are feasible. The datasheet specifies a nominal 5–9ms range for CRT = 1500pF, but scaling is linear - e.g., 1µF yields ~4.6 seconds. Leakage current becomes dominant beyond ~10µF, reducing accuracy.

Does LTC2900-2CDD#PBF support negative voltage monitoring?

Yes, the LTC2900-2CDD#PBF supports negative voltage monitoring via its –ADJ mode on the V4 input. In this mode, an external resistor divider connects between the negative supply and VREF (1.210V), with the tap applied to V4. The trip point is calculated as VTRIP = VREF × (R3/R4), enabling accurate supervision of rails like –5V or –12V. The datasheet provides Table 3 with validated 1% resistor values for common negative supplies.

How does the push-pull RST output of LTC2900-2CDD#PBF differ from the open-drain version?

The LTC2900-2CDD#PBF uses a push-pull RST output actively driven high to V2 (VOH ≥ 0.8×V2 at 200µA), eliminating reliance on external pull-up resistors. In contrast, the LTC2900-1 variant has an open-drain RST with weak internal pull-up (~6µA to V2), requiring external pull-ups for logic-high assertion. This makes the LTC2900-2CDD#PBF more robust in noisy environments and compatible with CMOS inputs without additional components.

Can LTC2900-2CDD#PBF monitor fewer than four supplies?

Yes, the LTC2900-2CDD#PBF can monitor fewer than four supplies. Unused inputs (e.g., V3 or V4) should be tied above their respective threshold voltages - for example, connecting V3 to V2 ensures it remains above the 2.5V or 1.8V threshold. The device asserts RST only when *any* monitored input falls below its programmed threshold, so unmonitored inputs must be held valid to prevent false resets. No reconfiguration is needed beyond proper biasing.

What is the purpose of the VPG pin on LTC2900-2CDD#PBF?

The VPG pin on LTC2900-2CDD#PBF selects one of 16 predefined voltage threshold combinations (e.g., 5V/3.3V/2.5V/1.8V) or adjustable modes via a resistor divider between VREF and GND. The ratio VPG/VREF determines the configuration - Table 1 in the datasheet lists exact 1% resistor pairs (e.g., 59.0kΩ/40.2kΩ for 5V/3.3V/2.5V/1.8V). This single-pin programming eliminates jumpers or configuration registers, simplifying layout and firmware-free setup.