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MAX77680 Datasheet and Technical Info

MAX77680

Introduction

The MAX77680 from Maxim Integrated is a highly integrated power management IC targeted at space-constrained, battery-powered applications. This chip combines a high-efficiency step-down DC-DC converter, real-time clock, multiple LDO regulators, and housekeeping monitoring into a tiny 3mm x 3mm WLP package.

In this article, we will explore the key technical details from the MAX77680 datasheet. This includes its features, electrical characteristics, application circuits, and usage considerations. For designers working on size-optimized wearables, medical devices, or IoT sensors, the MAX77680 provides an ideal power management solution.

Key Features

  • High efficiency 1.8MHz step-down converter with 1A peak output
  • Wide 2.9V to 5.5V input voltage range
  • Multiple LDO outputs: 1.8V, 2.5V, 3.3V, 5V at 150mA each
  • Integrated real-time clock with alarm function
  • Housekeeping and telemetry for voltage/current/temperature
  • Watchdog timer, power-on reset, and fault protections
  • 3mm x 3mm wafer level package (WLP)

Functional Block Diagram

The MAX77680 integrates a wealth of functions into a single tiny chip:

Show Image

Key blocks:

  • Step-down DC-DC converter with 1.8MHz switching frequency
  • LDO1/2/3/4 linear regulators with enable control
  • Real-time clock with alarm capabilities
  • Analog front end for voltage/current/temp telemetry
  • Fault protection and housekeeping logic

Step-down DC-DC Converter

The step-down converter is the heart of the MAX77680, allowing wide input voltage range and efficient conversion to a lower voltage.

Features:

  • Up to 95% efficiency
  • 2.9V to 5.5V input range
  • Adjustable output voltage from 0.8V to 3.4V
  • 1A peak output current
  • 1.8MHz fixed switching frequency
  • PFM/PWM low power modes

The switching converter uses a current-mode control scheme for fast transient response and stability. An internal compensating ramp simplifies loop compensation design.

For light load efficiency, a Power-Save Mode automatically reduces switching frequency based on output current. Full shutdown is also available to disable the DC-DC converter when not needed.

LDO Regulators

Four integrated 150mA LDO regulators provide auxiliary supply rails from the main converter output:

OutputVoltage
LDO11.8V
LDO22.5V
LDO33.3V
LDO45V

Each LDO can be enabled/disabled via an EN control pin. This allows unused regulators to be shut off for power savings.

RTC and Alarm

An integrated real-time clock keeps track of time in battery backed operation. Useful features include:

  • Calendar mode with automatic leap year compensation
  • 24-hour timekeeping
  • Alarm function with interrupt
  • Watchdog timer for system health monitoring
  • 1Hz clock output pin

With only a 32kHz crystal and backup battery, the RTC can maintain timekeeping for years. The alarm allows wake up events to be scheduled by an MCU.

Telemetry and Protection

For monitoring system health, the MAX77680 provides analog telemetry of critical parameters:

  • Input voltage
  • DC-DC output voltage
  • LDO voltages
  • DC-DC output current
  • Die temperature

These signals allow an MCU to digitize and monitor for out of range conditions indicating a fault. Protection features include UVLO, power-on reset, and watchdog timer.

Recommended Application Circuit

A typical MAX77680 application schematic looks like this:

Show Image

The key components are:

  • C1/C2 – DC-DC converter input/output caps
  • L1/D1 – DC-DC inductor and diode
  • C3-C7 – LDO output capacitors
  • R1 – Feedback resistor divider for DC-DC
  • Q1 – External FET for DC-DC (1A rating)
  • X1 – 32kHz RTC crystal
  • FB1 – Battery for RTC backup

This configuration allows generating multiple regulated rails from a single lithium ion cell input.

Package Options

The MAX77680 is available in two tiny package options optimized for space-constrained applications:

PackageSizePitch
wafer-level package (WLP)3mm x 3mm0.35mm
12-bump WLP2mm x 2mm0.4mm

Both packages allow excellent PCB layout efficiency. The WLPs use bump interconnects rather than pins or leads.

Electrical Characteristics

Key DC and AC parameters from the MAX77680 datasheet:

DC-DC Converter

ParameterConditionMinTypMaxUnit
Input Voltage2.95.5V
Output Voltage0.83.4V
Feedback Voltage0.7880.80.812V
EfficiencyVIN=3.6V95%
Shutdown IQEN=0V26uA

LDO Regulators

ParameterConditionMinTypMaxUnit
Output Voltage 1.8V1.7821.81.818V
Output Voltage 2.5V2.4852.52.515V
Output Voltage 3.3V3.2793.33.321V
Output Voltage 5V4.9555.05V
Dropout VoltageIOUT=150mA0.20.4V
Quiescent CurrentEN=0V15uA

RTC

ParameterConditionMinTypMaxUnit
AccuracyTA=25°C±3ppm
Frequency31.2532.76834.286kHz
Alarm Accuracy±60sec
Backup Battery LifeVBAT=3V6months

Conclusion

The MAX77680 delivers sophisticated power management and monitoring in an extremely compact footprint. With its high efficiency DC-DC converter, LDOs, RTC, and telemetry, it integrates all essential functions needed for space-constrained battery-powered devices. Engineers can leverage the MAX77680 to reduce system size and cost.

Frequently Asked Questions

Q: What is the main benefit of the MAX77680 compared to using discrete solutions?

A: The MAX77680 saves PCB space by combining many functions like the DC-DC converter, LDOs, and RTC into one tiny chip. This simplifies design and lowers BOM cost.

Q: What external components are required around the MAX77680?

A: At minimum it requires input/output capacitors for the DC-DC converter, an inductor, and feedback resistors. LDO caps and a DC-DC FET are also typical.

Q: Does the MAX77680 require an external MCU?

A: Yes, a host MCU is needed to configure the MAX77680, receive telemetry, set alarm times, etc. The IC contains no programmable logic itself.

Q: What packages is the MAX77680 available in?

A: It comes in a 3mm x 3mm WLP and an even smaller 2mm x 2mm WLP package. These provide excellent PCB space savings.

Q: What is the main limitation of the MAX77680 DC-DC converter?

A: The DC-DC converter is limited to 1A peak output current. For higher current applications, parallel chips or a discrete solution may be required.

 

 

 

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