TK653XX

The TK653xx mid power step-down converter is designed for portable battery powered systems, capable of operating from single Li-ion battery cells or two NiCad battery cells. The TK653xx provides the power switch, synchronous rectifier, and the control circuit for a buck step-down converter. Only three external components are required to complete the step-down conversion.

The TK653xx provides laser-trimmed output voltages ranging from 1.8 V to 3.3 V. The low resistance MOSFET switch and synchronous rectifier allow average currents up to 800 mA, while maintaining peak efficiencies up to 95%. A low-battery threshold and turn-off threshold can be individually programmed by the user, utilizing a single resistor divider connected to the Low Battery Input (LBI) pin. When the resistively-divided supply voltage on the LBI pin drops below approximately 1.25 V, the Low Battery Output (LBO) pin will become asserted. The dual-function LBI pin can alternatively be used as a Standby (SB) pin. Driving the SB pin low will disable the TK653xx and drop the quiescent current on the input supply to approximately 10 A.

Pulse Burst Modulation (PBM) is used to regulate the voltage at the V_OUT pin of the IC. When the output voltage of the TK653xx drops below the regulation threshold, a current pulse is transferred from the input supply to the output. The TK653xx utilizes a proprietary control scheme, where the average amplitude of the current pulse is varied depending upon the current loads. The proprietary architecture allows fast transient response and minimal ripple while maintaining ease-of-use and low component count.

The TK653xx is available in SOP-8 and DIP-8 packages.