TK65420

All Pins Except GND ............................................... 6.5 V
Power Dissipation (Note 1) ............................... 400 mW
Storage Temperature Range ................. -55 to +150 °C
Operating Temperature Range .................-20 to +80 °C
Junction Temperature ......................................... 150 °C
Lead Soldering Temperature (10 s.) ................... 235 °C

The TK654xx low power step-down converter is designed for portable battery systems, capable of operating from a single Li-ion battery cell or multiple alkaline or rechargeable (NiCd or NiMH) battery cells (up to 6 V). The TK654xx provides the power switch, synchronous rectifier, and the control circuit for a buck step-down converter. Only two external components are required to complete the stepdown conversion.

The TK654xx 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 200 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 1.22 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 TK654xx and drop the quiescent current on the input supply to approximately 18 A.

Pulse Current Amplitude control is used to regulate the voltage at the V_OUT pin of the IC. When the output voltage of the TK654xx drops below the regulation threshold, a current pulse is transferred from the input supply to the output. The TK654xx 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 TK654xx is available in a miniature 6-pin SOT23L-6 surface mount package.