MAX17085B

PRODUCTION

Integrated Charger, Dual Main Step-Down Controllers, and Dual LDO Regulators

All-in-One IC Solution Combines Battery Charger and System Power

Data Sheet (Rev. 2) Product Selection Table

Part Models: 2
1ku List Price: Starting From $4.50

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Overview

All-in-One Charger Plus Dual Main Step-Down Controllers
5V/100mA and 3.3V/50mA LDO Regulators
Main
- Dual Quick-PWM with Fast Transient Response and Extended On-Time
- 300kHz to 800kHz Switching Frequency
- Fixed 5V and 3.3V SMPS Outputs
- Low-Noise Ultrasonic Mode
- Autoretry Fault Protection
Charger
- High Switching Frequency (1.4MHz)
- Selectable 2-, 3-, and 4-Cell Battery Voltage
- Automatic Selection of System Power Source
- Internal Charge-Pump for Adapter n-channel MOSFETs Drive
- ±0.4% Accurate Charge Voltage
- ±2.5% Accurate Input Current Limiting
- ±3% Accurate Charge Current
Monitor Outputs for
- AC Adapter Current (±2% Accuracy)
- Battery Discharge Current (±2% Accuracy)
- AC Adapter OK
Analog/PWM (100Hz to 500kHz) Adjustable Charge Current Setting
AC Adapter Overvoltage and Overcurrent Protection

The MAX17085B is an all-in-one notebook power solution integrating a multichemistry battery charger, dual fixed output Quick-PWM™ step-down controllers, and dual keep-alive linear regulators:

Charger: The high-frequency (~1.4MHz) multichemistry battery charger uses a current-mode, fixed inductor current ripple architecture that significantly reduces component size and cost. Low-offset sense amplifiers allow the use of low-value sense resistors for charging and input current limit.

The charger uses n-channel switching MOSFETs. Adjustable charge current, charge voltage, and cell selection allow for flexible use with different battery packs. Charge current is set by an analog control input, or a PWM input. High-accuracy current-sense amplifiers provide fast cycle-by-cycle current-mode control to protect against short circuits to the battery and respond quickly to system load transients. Additionally, the charger provides a high-accuracy analog output that is proportional to the adapter current.

An integrated charge pump controls an n-channel adapter selector switch. The charge pump remains active even when the charger is off. When the adapter is absent, a p-channel MOSFET selects the battery.

Main SMPS: The dual Quick-PWM step-down controllers with synchronous rectification generate the 5V and 3.3V main power in a notebook. Low-side MOSFET sensing provides a simple low-cost, highly efficient valley current-limit protection. The MAX17085B also includes output undervoltage, output overvoltage, and thermal-fault protection.

Separate enable inputs for each SMPS and a combined open-drain power-good output allow flexible power sequencing. Voltage soft-start reduces inrush current, while passive shutdown discharges the output through an internal switch. Fast transient response, with an extended on-time feature reduces output capacitance requirements. Selectable pulse-skipping mode and ultrasonic mode improve light-load efficiency. Ultrasonic mode operation maintains a minimum switching frequency at light loads, minimizing audible noise effects.

Dual LDO Regulators: An internal 5V/100mA LDO5 with switchover can be used to either generate the 5V bias needed for power-up or other lower power "always-on" suspend supplies. Another 3.3V/50mA LDO3 provides "always-on" power to a system microcontroller.

Applications

2-to-4, Li+-Cell, Battery-Powered Devices
5V and 3.3V Supplies
Notebook Computers
PDAs and Mobile Communicators

Part Models: 2
1ku List Price: Starting From $4.50

Documentation

Data Sheet 1

MAX17085B: Integrated Charger, Dual Main Step-Down Controllers, and Dual LDO Regulators Data Sheet (Rev.2) 05/10/2012

Reliability Data 1

MAX17085B Reliability Data 01/12/2023

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
MAX17085BETL+	40-LFCSP-5X5X0.75	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
MAX17085BETL+T	40-LFCSP-5X5X0.75	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Evaluation Kits

Evaluation Kit for the MAX17085B

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Features and Benefits

Analog Control Charge Current, Voltage, and Input Source Current
Monitor Outputs
- AC Adapter Current/Battery Discharge Current
- AC Adapter Presence
- Valid Step-Down Converter Output Voltages
5V, Up to 8A Step-Down Converter Outputs
3.3V, Up to 8A Step-Down Converter Outputs
5V, 3.3V Linear Regulator Outputs
Automatic Power-Source Selection
Up to 17.5V (4-Cell) Battery Voltage
8V to 22V Input Operation
4A Input Current Limit
System Short-Circuit Protection
Cycle-by-Cycle Current Limit
Up to 1.4MHz Frequency Operation (Charger)
Multichemistry Battery Charger
Fully Assembled and Tested

Product Details

The MAX17085B evaluation kit (EV kit) is a complete and fully assembled and tested PCB that features the MAX17085B IC, a highly integrated, multichemistry battery-charger controller with dual step-down converters and dual LDOs. The EV kit is capable of supplying power to a system load while simultaneously charging multichemistry battery packs. During operation, the EV kit circuit automatically selects the ADAPTER input or the battery as the main power source for supplying power to the system load and step-down converters. Whenever the EV kit circuit current limit is exceeded, the battery-charge current is reduced automatically, giving priority to the system load and converters.

The EV kit's input source-current limit, battery-charge voltage, maximum battery-charge current threshold, and output current limit on the step-down converters are configurable. These thresholds are adjusted by using on-board circuitry, or by connecting analog signals to the EV kit. Digital output signals indicate the presence of a valid ADAPTER and valid step-down converter voltages. An analog output signal indicates the total current drawn from either the adapter or the battery.