LTC4162EUFD-FST#PBF datasheet(15/52 Pages) AD

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LTC4162-F

Rev A

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OPERATION

Introduction

The LTC4162 is an advanced power manager and switch-

ing battery charger utilizing a high efficiency synchronous

step-down switching regulator.

Using multiple feedback control signals, power is deliv-

ered from the input to the battery by a 1.5MHz constant-

frequency step-down switching regulator. The switching

regulator reduces output power in response to one of its

four regulation loops including battery voltage, battery

charge current, input current and input voltage.

The switching regulator is designed to efficiently transfer

power from a variety of possible sources, such as USB

ports, wall adapters and solar panels, to a battery while

minimizing power dissipation and easing thermal budget-

ing constraints. Since a switching regulator conserves

power, the LTC4162 allows the charge current to exceed

the source's output current, making maximum use of the

allowable power for battery charging without exceeding

thesource'sdeliveryspecifications.Byincorporatinginput

voltage and system current measurement and control

systems, the switching charger ports seamlessly to these

sources without requiring application software to monitor

and adjust system loads. By decoupling the system load

from the battery and prioritizing power to the system,

the instant-on PowerPath architecture ensures that the

system is powered upon input power arrival, even with a

completely dead battery.

Two low power charge pumps drive external MOSFETs to

provide low loss power paths from the input supply and

battery to the system load while preventing the system

node from back-driving the input supply or overcharging

the battery. The power path from the battery to the system

load guarantees that power is available to the system even

if there is insufficient or absent power from VIN. A wide

range of input current settings as well as battery charge

current settings are available by software control and by

choosing the values of input and charge current sense

resistors RSNSI and RSNSB.

A measurement subsystem periodically monitors and

reports on a large collection of system parameters via the

I2C port. An interrupt subsystem can be enabled to alert

the host microprocessor of various status change events

so that system parameters can be varied as needed. All

of the status change events are maskable for maximum

flexibility. For example, features such as battery presence

detection and battery impedance measurement are easily

enabled.

To eliminate battery drain between manufacture and sale,

a ship-and-store feature reduces the already low battery

drain current even further.

The input undervoltage control loop can be engaged to

keeptheinputvoltagefromdecreasingbeyondaminimum

level when a resistive cable or power limited supply such

as a solar panel is providing input power. A maximum

power point tracking algorithm using this control loop

can be deployed to maximize power extraction from solar

panels and other resistive sources.

Finally, the LTC4162 has a digital subsystem that provides

substantial adjustability so that power levels and status

information can be controlled and monitored via the

conventional I2C port.

LTC4162 Digital System Overview

The LTC4162 contains an advanced digital system which

can be accessed using the I2C port. Use of the I2C port

is optional, it can be used extensively in the application

or not at all, as dictated by the application requirements.

Cell count, charge current, input current regulation and

switchingchargerfrequencyareallexternallyconfigurable

without using the I2C port. For applications requiring the

LTC4162'sadvanceddigitalfeatures,theI2Cportprovides

a means to use status and A/D telemetry data from the

measurement system, monitor charger operation, config-

ure charger settings (e.g. charge voltage, charge current,

temperatureresponse,terminationalgorithm,etc),enable,

disable, read and clear alerts, activate the low power ship

mode, and enable/disable the battery charger.

Power Path Controller

The LTC4162 features input and output N-channel MOS-

FET charge pump gate drivers. These drivers make up a

dual unidirectional power path system that allows power

to be delivered to the system load by either the input

supply or the battery, whichever is greater. Only one of

LTC4162EUFD-FST#PBF Datasheet(PDF) 15 Page - Analog Devices

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