Analog Devices Inc./Maxim Integrated MAX4921BETD+

Overview

MAX4921BETD+ from Maxim Integrated is an overvoltage protection controller with integrated 1.8A pFET switch, designed for battery-powered portable devices requiring robust input fault protection up to +28V. It features a preset 4.65V overvoltage lockout (OVLO), 2.35V undervoltage lockout (UVLO), and current-limiting short-circuit protection with 4–16ms blanking time - enabling safe battery switchover in cell phones and digital cameras.

For engineers reviewing the MAX4921BETD+ datasheet, MAX4921BETD+ pinout, MAX4921BETD+ application, or MAX4921BETD+ equivalent, key selection criteria include its 14-pin TDFN package (3mm × 3mm), internal pFET R_ON ≤ 120mΩ over temperature, low 0.4µA shutdown current, and logic-controlled power-up sequencing via PWR_HOLD, HP_PWR, and PWR_ON inputs.

Technical Context

The MAX4921BETD+ implements dual-stage fault management: first, a 25ms input voltage debounce window validates stable adapter presence before asserting ACOK; second, a programmable current-limit blanking period (4–16ms) distinguishes inrush from true short-circuit events at BTO. Its GN1 gate driver uses an on-chip charge pump to deliver ~2×VIN (clamped to 7.8–8.4V) for driving external nFETs, while GP1 provides clamped gate control for external pFETs.

Control logic integrates three independent turn-on triggers - IN (adapter detection), HP_PWR (car-kit detection), and PWR_ON - each initiating a 1.2s one-shot that requires latching via PWR_HOLD to sustain battery switchover. Thermal shutdown activates at +135°C and resets only after junction cools below +125°C and control inputs are cycled.

Key Specifications

Pinout & Package

MAX4921BETD+ is housed in a 14-pin TDFN package (3mm × 3mm) with exposed thermal paddle (EP), optimized for low-inductance layout and thermal performance in portable battery systems.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar overvoltage protection controller applications.

Compared with MAX4920BETD+, MAX4921BETD+ enables deeper battery discharge (2.35V UVLO) and earlier overvoltage cutoff (4.65V), making it optimal for compact single-cell Li-ion devices; versus TPS259211DSGR, it trades external component count for fixed, production-validated protection thresholds and smaller footprint.

Availability

MAX4921BETD+ is available at Aetrix Electronics and suitable for cell phone power management, digital still camera subsystems, MP3 player battery protection, and PDA car-kit interface applications requiring stable component supply and long-term lifecycle support.

Supply support for MAX4921BETD+ 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

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and portable applications.

The MAX4919B/MAX4920B/MAX4921B family delivers integrated battery switchover logic with overvoltage, undervoltage, and overcurrent protection - engineered specifically for space-constrained, battery-powered consumer electronics requiring robust adapter and car-kit compatibility.

FAQ

What is the overvoltage lockout (OVLO) threshold for MAX4921BETD+?

The MAX4921BETD+ has a fixed overvoltage lockout threshold of 4.65V (typical), with a guaranteed range of 4.35V to 4.95V across -40°C to +85°C. This precise trip point ensures reliable disconnection before adapter faults damage downstream Li-ion batteries or system circuitry, and is factory-trimmed - no external components required to set the threshold.

How does MAX4921BETD+ handle short-circuit conditions at the BTO output?

When a short occurs at BTO, MAX4921BETD+ limits current to ≥1.8A and applies a 4–16ms blanking period to ignore inrush transients. If the fault persists beyond this window, the internal pFET latches off and remains disabled until one of the enable inputs (IN, HP_PWR, PWR_ON) is cycled. This behavior is confirmed in the Electrical Characteristics table and Figure 9 of the MAX4921BETD+ datasheet.

What is the function of the PWR_HOLD pin on MAX4921BETD+?

PWR_HOLD on MAX4921BETD+ serves as the latching input that maintains internal pFET conduction after the initial 1.2s one-shot (triggered by IN or HP_PWR) expires. If PWR_HOLD transitions high during the one-shot window and remains asserted, the pFET stays on indefinitely - enabling sustained battery power during microprocessor boot and system initialization. This behavior is detailed in Figures 7 and 8 of the MAX4921BETD+ functional documentation.

Does MAX4921BETD+ support thermal shutdown, and what are the trip/reset thresholds?

Yes, MAX4921BETD+ includes thermal shutdown with a trip threshold of +135°C (junction) and automatic reset at +125°C. When activated, the internal pFET turns off and remains latched off until both the temperature falls below reset level and the enable condition (e.g., PWR_HOLD or HP_PWR) is cycled. This protection is implemented in silicon and specified in the Absolute Maximum Ratings section of the MAX4921BETD+ datasheet.

Can MAX4921BETD+ operate with a single-cell Li-ion battery, and what is its minimum operating voltage?

Yes, MAX4921BETD+ is explicitly designed for single-cell Li-ion systems, with a 2.35V (typical) undervoltage lockout (UVLO) threshold and guaranteed operation down to 2.20V. This allows full utilization of the battery's discharge curve - supporting operation well below the 3.0V typical cutoff of many competing controllers - and is validated across the full -40°C to +85°C temperature range per the MAX4921BETD+ Electrical Characteristics table.