MAX17085B 具有两路降压型主控制器和两路LDO稳压器

MAX17085B 具有两路降压型主控制器和两路LDO稳压器的集成充电器

概述

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.

关键特性

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

应用/使用

2-to-4, Li+-Cell, Battery-Powered Devices
5V与3.3V电源
笔记本电脑
PDA与移动通信

Functional Diagram