Linear charger for portable electronic devices

Advanced Analogic Technologies (Analogictech) has introduced a single-input 1.6A linear charger targeted at portable electronic devices such as mobile phones and GPS navigation systems.

The AAT 3698 charger, featuring 28V input protection and 50mA low-dropout (LDO), manages the charging, sequencing and protection of lithium-ion- and lithium-polymer-powered portable devices.

The device incorporates safety features that adjust for excessive temperature or voltage, up to 28V, to avoid overcharging or other damage to the battery during charging.

Roger Smullen, product marketing manager at Analogictech, said: 'A device's ability to maximise its battery life and charging speed while minimising power loss is a critical consideration to its acceptance in the consumer marketplace.

'The AAT3698 is able to deliver these performance characteristics through USB connectivity or an AC adapter, giving designers even more options to enable broad adoption,' he added.

Part of Analogictech's Battery Manager Total Power Management IC (TPMIC) product range, the AAT3698 is a linear battery charger IC developed for single-cell lithium-ion and lithium-polymer batteries.

Able to manage input voltage of up to 7V, the IC integrates many features to increase design flexibility and to facilitate design-in.

Among these are a 5V/50mA LDO that can provide additional power to an external device such as a radio in a wireless communication product.

This regulator is enabled at all times regardless of the status of the charger and is protected by an over-voltage-protection (OVP) switch.

The AAT3698 is a small standalone charger solution that requires only two resistors and four small capacitors to operate and comes in a small, lead-free, 14-pin, 4 x 4mm thin-quad flat no-lead (TQFN) package.

The AAT3698 precisely regulates battery voltage for battery cells through a low RDS(ON) switch after it has reached 4.2V.

The charging current can be set by an external resistor up to 1.6A.

Aside from the IC's built-in OVP circuit that helps to prevent damage to the battery and the charging circuitry, other fault conditions are monitored in real time.

In the case of an over-current, battery over-voltage, short-circuit or over-temperature failure, the device will automatically shut down, thereby protecting the charging device, the control system and the battery under charge.

A status monitoring output pin is provided to indicate charging activity.

This open-drain output pin can be used to drive an external LED as a charging indicator.

When the battery voltage has reached the constant voltage level, the AAT3698 has two charge termination and recharge modes - one controlled by the charger (AAT3698-1) and one where the charge termination and recharge is managed by the host (AAT3698-2).

Back to top