Microchip Technology MCP1642BT-18I/MC

Overview

MCP1642BT-18I/MC from Microchip Technology is a synchronous step-up DC-DC converter with true output disconnect shutdown, fixed 1.8V output, 1 MHz switching frequency, 0.65V typical start-up voltage, and 96% peak efficiency. It delivers up to 175 mA at 1.2V input and regulates precisely using an internal feedback divider - designed for single-cell alkaline/Li-ion battery-powered microcontroller systems requiring ultra-low-voltage start-up and load isolation.

For engineers reviewing the MCP1642BT-18I/MC datasheet, MCP1642BT-18I/MC pinout, MCP1642BT-18I/MC application, or MCP1642BT-18I/MC equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters across temperature, real-world load capability data, and two rigorously cross-checked alternative parts for low-input-voltage boost applications.

Technical Context

The MCP1642BT-18I/MC implements fixed-frequency (1 MHz) peak-current-mode PWM control with adaptive slope compensation and integrated N-Channel (0.15 Ω R_DS(ON)) and P-Channel (0.3 Ω R_DS(ON)) synchronous switches. Its low-voltage start-up circuitry enables operation from 0.65V input while limiting inrush current via controlled open-loop charging of V_OUT before closed-loop regulation begins.

True output disconnect is achieved by fully turning off both internal MOSFETs during shutdown (EN = GND), eliminating DC path leakage (<1 µA I_QSHDN) and preserving output capacitor charge. The 1.21V internal reference and fixed 1.8V output are set by an on-die resistor divider; pin 2 (VFB) is unconnected in this variant.

Key Specifications

Pinout & Package

Package: 8-Lead MSOP (3.0 mm × 4.9 mm, 0.65 mm pitch), lead-free and RoHS-compliant. Exposed thermal pad not present in MSOP variant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous boost regulator applications.

Compared with TPS61200DRCT and ADP5070ACPZ-R7, the MCP1642BT-18I/MC uniquely combines fixed 1.8V output, sub-1V start-up, true output disconnect, and MSOP packaging - making it the sole option for space-constrained, ultra-low-VIN battery systems demanding zero-shutdown leakage and deterministic power sequencing.

Availability

MCP1642BT-18I/MC is available at Aetrix Electronics and suitable for portable medical sensors, PIC® MCU power supplies, wireless sensor nodes, USB emergency backup chargers, and handheld instrumentation requiring stable component supply across long production lifecycles.

Supply support for MCP1642BT-18I/MC 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

Microchip Technology Inc. is a leading provider of microcontroller, mixed-signal, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with high-reliability semiconductor products.

The MCP1642B/D family was engineered specifically for ultra-low-input-voltage boost conversion in single-cell battery systems - prioritizing start-up robustness, shutdown isolation, and integration to reduce external component count in space-constrained portable designs.

FAQ

What is the minimum input voltage required for MCP1642BT-18I/MC to start regulating 1.8V output?

The MCP1642BT-18I/MC starts regulation at 0.65V typical (0.8V max) with a 1 mA resistive load. This is verified per DS20005253A-page 3, Table 1-1, Note 1. Below 0.35V, the device remains operational but cannot sustain regulation under load - making it ideal for exhausted alkaline cells. The MCP1642BT-18I/MC achieves this via dedicated low-voltage start-up logic that pre-charges VOUT before entering closed-loop PWM mode.

Does MCP1642BT-18I/MC support true output disconnect, and how is it implemented?

Yes, MCP1642BT-18I/MC implements true output disconnect by fully disabling both the internal N-Channel boost switch and P-Channel synchronous rectifier when EN is pulled low. This breaks the DC path between VIN and VOUT, reducing shutdown current to ≤1 µA and preserving output capacitor charge. This behavior is exclusive to the "B" suffix (MCP1642B) and is documented in Section 4.1.1 and Table 4-1 of the datasheet.

What package type and thermal characteristics does MCP1642BT-18I/MC use?

MCP1642BT-18I/MC is supplied in an 8-Lead MSOP package (3.0 mm × 4.9 mm) with θ_JA = 211°C/W. Unlike the DFN variant, the MSOP version lacks an exposed thermal pad. The device operates from –40°C to +85°C ambient and includes thermal shutdown at 150°C (35°C hysteresis). Layout guidance requires connecting PGND and SGND at a single point near the IC to maintain regulation accuracy.

Can MCP1642BT-18I/MC be used with a 5.0V output requirement?

No - MCP1642BT-18I/MC is a fixed 1.8V output variant. Its internal feedback divider is trimmed for 1.8V ±3% and pin 2 (VFB) is unconnected. To achieve 5.0V output, use MCP1642BT-50I/MC (fixed 5.0V) or MCP1642BT-ADJI/MC (adjustable 1.8–5.5V). Attempting to force 5.0V with the -18 variant will result in severe regulation error and potential instability due to mismatched feedback ratio.

How does the Power Good (PG) pin function on MCP1642BT-18I/MC?

The PG pin is an open-drain output that pulls low when VOUT falls below 90% of 1.8V (i.e., <1.62V). It features 600 µs delay and 3% hysteresis, providing clean, glitch-free signaling to MCUs. A pull-up resistor (typically 10–100 kΩ to VOUT or system rail) is required. PG status is independent of EN state - it asserts only based on actual VOUT regulation, ensuring reliable power monitoring in the MCP1642BT-18I/MC design.