TK65127

The TK651xx low power step-up DC-DC converter is designed for portable battery powered systems, capable of operating from a single battery cell down to 0.9 V. The TK651xx provides the power switch and the control circuit for a boost converter. The converter takes a DC input and boosts it up to a regulated 2.7, 3.0 or 3.3 V output .

The output voltage is laser-trimmed. A Low Output Indicator detector (LOI) monitors the output voltage and provides an active low microprocessor reset signal whenever the output voltage falls below an internally preset limit. An internal Undervoltage Lockout (UVLO) circuit is utilized to prevent the inductor switch from remaining in the "on" mode when the battery voltage is too low to permit normal operation. Pulse Burst Modulation (PBM) is used to regulate the voltage at the V_OUT pin of the IC. PBM is the process in which an oscillator signal is gated or not gated to the switch drive each period. The decision is made just before the start of each cycle and is based on comparing the output voltage to an internally-generated bandgap reference. The decision is latched, so the duty ratio is not modulated within a cycle. The average duty ratio is effectively modulated by the "bursting" and skipping of pulses which can be seen at the SW pin of the IC. Special care should be taken to achieve reliability through the use of Oxide, double Nitride passivation. The TK651xx is available in a miniature 6-pin SOT-23L-6 surface mount package.

Customized levels of accuracy in oscillator frequency and output voltage are available.