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TS52001

Version 1.3

Specifications subject to change

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Copyright © 2011, Triune Systems, LLC

FUNCTIONAL DESCRIPTION

The TS52001 is a fully-integrated Li-Ion battery charger IC based on a highly-efficient switching topology. It includes a

Maximum Power Point Tracking (MPPT) function to optimize its input voltage to extract the maximum possible power from a

photovoltaic cell. It includes configurability for termination voltage, charge current and a host of other variables to allow

optimum charging conditions for a wide range of Li-Ion batteries. A 1 MHz internal switching frequency facilitates low-cost LC

filter combinations.

When the battery voltage is below 3.0 volts, the device will enter a pre-charge state and apply a small, programmable charge

current to safely charge the battery to a level for which full charge current can be applied. Once the full charge mode has been

initiated, the device will maximize available charge current to the battery by adjusting its duty cycle to regulate its input voltage

to the Maximum Power Point (MPP) voltage of the photovoltaic cell. If sufficient current is available from the PV cell to exceed

the safe 1C charge rate of the battery, then the programmable 1C current limit function will take precedence over the MPP

control function and the PV cell voltage will rise above the MPP value.

When the battery voltage has increased enough to go into maintenance mode, the PWM control loop will force a constant

voltage across the battery. Once in constant voltage mode, current is monitored to determine when the battery is fully charged.

This regulation voltage as well as the 1C charging current can be set to change based on battery temperature. There are 4

temperature ranges where these can be set independently, 0-10°C, 10-45°C, 45-50°C and 50-60°C. The 0°C and 60°C thresholds

will stop charging and have 10 degrees of hysteresis. The intermediate points have 1 degree of hysteresis.

INTERNAL PROTECTION DETAILS

Internal Current Limit

The current through the inductor is sensed on a cycle by cycle basis and if current limit is reached, it will abbreviate the cycle.

Current limit is always active when the regulator is enabled.

Thermal Shutdown

If the temperature of the die exceeds 170°C (typical), the SW outputs will tri-state to protect the device from damage. The nFLT

and all other protection circuitry will stay active to inform the system of the failure mode. Once the device cools to 160°C

(typical), the device will attempt to start up again. If the device reaches 170°C, the shutdown/restart sequence will repeat.

VIN Under-Voltage Lockout

The device is held in the off state until VIN reaches 3.15V. There is a 200mV hysteresis on this input, which requires the input

to fall below 2.95V before the device will disable.

Battery Over-Voltage Protection

The TS52001 has a battery protection circuit designed to shutdown the charging profile if the battery voltage is greater than

the termination voltage. The termination voltage can change based on user programming, so the protection threshold is set to

2% above the termination voltage. Shutting down the charging profile puts the TS52001 in a fault condition.

FAULT HANDLING

nFLT Pin Functionality

In the event of a battery over-voltage, the battery temperature being outside of the safe charging range or the full charge timer

expiring, charging will stop, and the nFLT pin will be pulled low. When the fault condition is no longer present, the device will

enter the INITIALIZE state, but the nFLT pin will remain low until register 0 is read. When the register 0 is read, the nFLT pin

will go high until a new fault is detected.

Other Faults

When an open thermistor, thermal shut down, VIN under-voltage, or top off time-out are detected, charging will immediately

stop and the corresponding bit in register 0 will be set. The device will enter the INITIALIZE state until the fault is no longer

detected.