Analog Devices Inc./Maxim Integrated MAX1722EZK+T

MAX1722EZK+T Step-Up DC-DC Converter Comprehensive Product Summary

The MAX1722EZK+T by Analog Devices Inc./Maxim Integrated stands out as a compact, high-efficiency, adjustable-output step-up (boost) DC-DC converter. Housed in a space-saving TSOT23-5 package, it’s tailored to meet the stringent demands of modern portable electronics, offering the flexibility to operate efficiently from voltage sources as low as a single alkaline, NiMH, or Li+ cell. With its positive adjustable output configuration, ultra-low quiescent current, and integrated synchronous rectification, the MAX1722EZK+T provides a robust and elegant solution for designers seeking to maximize battery life while maintaining a minimal PCB footprint.

Highlights and Performance Benefits of the MAX1722EZK+T

The MAX1722EZK+T distinguishes itself with a wealth of technical benefits designed for demanding low-power applications:

5μA quiescent supply current ensures industry-leading efficiency at light loads, critical for maximizing standby or sleep-mode battery life.

Up to 90% conversion efficiency thanks to a built-in synchronous rectifier, which eliminates the need for an external Schottky diode.

Wide 0.8V–5.5V input voltage range with guaranteed startup from voltages as low as 0.91V, making it ideal for single-cell-powered systems.

Adjustable output voltage (2V to 5.5V) accommodates a diversity of load requirements in portable devices.

Maximum output current capability up to 150mA, suitable for moderate-load subsystems.

1μA logic-controlled shutdown current allows deep sleep modes for system-level power savings.

±1% output voltage accuracy provides reliable regulation for sensitive analog or digital loads.

Internal noise reduction and EMI suppression circuitry minimize interference from inductor switching, a vital consideration in RF applications.

Primary Use Cases for the MAX1722EZK+T

Given its compactness and efficiency at low input voltages, the MAX1722EZK+T is especially suited for:

Pagers, remote controls, and remote wireless transmitters that demand low quiescent current.

Single or dual-cell battery-powered devices where size and battery life are critical.

Personal and medical electronics such as digital still cameras, MP3 players, and handheld instruments.

PDAs and modern wearable gadgets needing space-constrained, efficient power management.

Electrical Characteristics and Environmental Specifications of the MAX1722EZK+T

For effective selection and system-level design, the following electrical and regulatory details are critical:

Absolute Maximum Ratings: Input and output pins can tolerate up to +6V, currents up to 1A, and continuous power dissipation of 219.10mW at +70°C (must be derated above this temperature).

Operating Temperature Range: -40°C to +85°C, suitable for industrial and extended commercial environments.

RoHS and REACH Compliant for use in green designs.

JEDEC Moisture Sensitivity Level (MSL): 1 (Unlimited), supporting standard SMT assembly processes.

Operational Principles and Functional Architecture of the MAX1722EZK+T

The MAX1722EZK+T utilizes a pulse-frequency-modulation (PFM) control scheme, specifically designed for ultra-low-power operation:

Discontinuous, current-limited switching maintains high efficiency across widely varying loads without a dedicated oscillator, thus reducing standby losses.

The integrated synchronous rectifier uses a P-channel MOSFET to drastically cut rectifier losses during inductor discharge, eliminating the need for an external diode and freeing up valuable PCB area.

Internal noise-clamp circuitry actively suppresses EMI, addressing a common challenge in compact, RF-sensitive or medical environments.

Startup circuitry ensures reliable operation from depleted cells: the BATT pin powers critical logic during the low-voltage startup phase, guaranteeing operation down to 0.91V input.

Best Practices and Design Recommendations for Implementing the MAX1722EZK+T

To fully leverage the versatile capabilities of the MAX1722EZK+T, consider these design best practices:

Output Voltage Setting: Select feedback resistors R1 (100kΩ to 1MΩ) and R2 as per the standard formula to achieve target output voltages.

Inductor Selection: Choose a 10μH inductor for general applications; calculate peak switching currents and inductor saturation limits carefully. High inductance values can increase efficiency and reduce ripple but may restrict maximum output current if not paired appropriately with the controller’s on-time and current limits.

Output and Input Capacitors: Use low ESR ceramic capacitors for best performance; 10μF is generally satisfactory, but values may need to be increased for higher load transients or wide temperature operation.

For lowest voltage single-cell startup (as with the related MAX1723), include a Schottky diode if necessary, but for the MAX1722, internal circuitry suffices for startup below 1V.

Guidelines for PCB Design When Integrating MAX1722EZK+T

Optimized PCB layout is essential for noise performance and reliability:

Keep the ground paths between the IC, input, and output capacitors under 5mm; use solid ground planes wherever possible.

Minimize trace length to the feedback (FB) and LX pins to reduce susceptibility to noise and switching transients.

Place input and output capacitors as close as possible to the IC package to minimize voltage ripple and supply impedance.

Alternative Devices and Substitute Options for the MAX1722EZK+T

When evaluating alternatives or drop-in replacements for the MAX1722EZK+T, engineers may consider related solutions within the same family and beyond:

MAX1723: Offers similar functionality with the addition of an active-low shutdown and slight variations in the startup configuration; requires an external Schottky diode for minimum voltage startup below ~1.2V.

MAX1724: Features fixed output voltage options and shares the internal damping switch for EMI reduction.

For other brands, engineers should focus on selecting boost converters with comparable quiescent current, startup voltage, synchronous rectification, and miniature packaging, ensuring they meet or surpass the 0.91V startup and high-efficiency characteristics that define the MAX1722EZK+T.

Conclusion

: Assessing the MAX1722EZK+T for Compact Power Design

The MAX1722EZK+T step-up DC-DC converter exemplifies a modern approach to battery-powered and compact-system power supply design. Its unique blend of ultra-low quiescent current, efficient synchronous rectification, EMI suppression, and flexibility in output voltage configuration make it a strong candidate for engineers and procurement teams targeting ultra-portable electronics, devices with extended standby requirements, and any scenario demanding minimal power loss from small, cost-sensitive circuit footprints. By systematically considering the outlined application notes and design principles, professionals can successfully integrate the MAX1722EZK+T for robust, efficient, and competitive product designs.