Microchip Technology MCP1642D-50I/MS

Overview

MCP1642D-50I/MS from Microchip Technology is a synchronous step-up DC-DC converter with fixed 5.0V output, 1 MHz PWM switching, 0.65V minimum start-up voltage, 1.8A peak switch current limit, and input-to-output bypass shutdown mode. It delivers up to 1 A at 3.3V input to 5.0V output and targets low-voltage battery-powered systems such as single-cell Li-Ion USB backup chargers and PIC® MCU power rails.

For engineers reviewing the MCP1642D-50I/MS datasheet, MCP1642D-50I/MS pinout, MCP1642D-50I/MS application, or MCP1642D-50I/MS equivalent, key selection criteria include verified 5.0V fixed output accuracy (±3%), true input-to-output bypass behavior in shutdown (<1 µA IQ), MSOP-8 package thermal performance (θJA = 211°C/W), and compatibility with 4.7 µH inductors and 4.7–10 µF ceramic capacitors.

Technical Context

The MCP1642D-50I/MS implements peak-current-mode PWM control with adaptive slope compensation, fixed 1 MHz switching frequency, and integrated N-Channel (0.15 Ω RDS(ON)) and P-Channel (0.3 Ω RDS(ON)) synchronous switches. Its low-noise anti-ringing circuit suppresses switch-node oscillations during discontinuous conduction mode.

Startup begins at 0.65V (typical, 3.3V VOUT @ 1 mA) and sustains regulation down to 0.5V input (typical, 5.0V VOUT @ 1 mA). The EN pin uses ratio-metric logic thresholds (VIH > 75% VIN, VIL < 20% VIN), and the open-drain PG output asserts low when VOUT falls below 90% of nominal with 3% hysteresis.

Key Specifications

Pinout & Package

Package: 8-Lead MSOP (3.0 mm × 4.9 mm, 0.65 mm pitch), exposed pad not electrically connected - requires PCB thermal pad connection to SGND/PGND plane for thermal management (θJA = 211°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS61200DRCT and ADP5070ARMZ-R7, the MCP1642D-50I/MS uniquely combines fixed 5.0V output, verified 0.65V start-up, input-to-output bypass, and PG signaling in an MSOP-8 package - making it optimal for cost-sensitive, battery-constrained 5V systems requiring minimal external components and deterministic shutdown behavior.

Availability

MCP1642D-50I/MS is available at Aetrix Electronics and suitable for USB emergency backup chargers, PIC® MCU power rails, wireless sensor nodes, and hand-held instruments requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MCP1642D-50I/MS 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 is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and power management ICs for embedded control applications.

The MCP1642B/D family was designed specifically for ultra-low-input-voltage, high-efficiency boost conversion in portable battery-powered systems - emphasizing minimal external components, robust start-up from depleted cells, and application-specific shutdown modes.

FAQ

What is the minimum input voltage required for MCP1642D-50I/MS to start regulating 5.0V output?

The MCP1642D-50I/MS starts regulating 5.0V output at 0.65V typical (0.9V max) with a 1 mA resistive load, per DS20005253A-page 3. This low start-up voltage enables operation from single alkaline, NiMH, or deeply discharged Li-Ion cells. Once started, it sustains regulation down to 0.5V input (typical) at light loads. The MCP1642D-50I/MS achieves this using internal start-up logic that precharges VOUT before initiating PWM switching.

How does the input-to-output bypass mode work in MCP1642D-50I/MS during shutdown?

When EN is pulled low, the MCP1642D-50I/MS activates its input-to-output bypass mode by turning on the internal P-Channel MOSFET, creating a low-resistance path from VIN to VOUT. This allows the load to operate directly from the input source without conversion loss, drawing <1 µA quiescent current. Unlike the MCP1642B's true disconnect mode, this bypass preserves load power but does not isolate VOUT from VIN. The MCP1642D-50I/MS implements this behavior exclusively - it is not configurable.

Does MCP1642D-50I/MS require external feedback resistors to set its 5.0V output?

No. The MCP1642D-50I/MS uses an internal resistor divider (815 kΩ typical) to set its fixed 5.0V output; pin 2 (VFB) is unconnected (NC) and must remain floating. This eliminates external resistor placement errors, leakage paths, and board space - unlike adjustable variants (e.g., MCP1642D-ADJ) which require external RTOP/RBOT. The MCP1642D-50I/MS achieves ±3% output accuracy across temperature without user calibration.

What is the purpose of the PG (Power Good) pin on MCP1642D-50I/MS?

The PG pin on MCP1642D-50I/MS is an open-drain output that pulls low when VOUT falls below 90% of its nominal 5.0V value, with 3% hysteresis. It requires an external pull-up resistor (typically to VOUT or system rail) and sinks up to 5 mA. Engineers use PG to signal MCU reset, enable downstream regulators, or trigger fault logging. Its 600 µs delay and 250 µs response ensure clean timing relative to VOUT transients - a feature confirmed in DS20005253A-page 5 for the MCP1642D-50I/MS.

Can MCP1642D-50I/MS operate with a 4.7 µH inductor and 4.7 µF output capacitor?

Yes. The MCP1642D-50I/MS is characterized and validated with a 4.7 µH shielded inductor and 4.7–10 µF ceramic output capacitor (DS20005253A-page 2, Typical Application). This combination supports stable 1 MHz PWM operation, meets ripple and transient requirements for 5.0V loads up to 1 A, and aligns with Microchip's reference design. Using these values ensures compliance with the MCP1642D-50I/MS's internal compensation and avoids instability or excessive EMI.