The TPS6735 combines a current-mode pulsewidth-modulation (PWM) controller with an on-chip p-channel MOSFET. The TPS6735 is a simple solution for converting a nominal 5-V input to a negative 5 V output. It uses only five external components to deliver up to 200 mA at 78% efficiency from an input as low as 4.5 V. Its 150-kHz oscillator allows for selection of small surface mount components for compact power supply design.
Soft start can be implemented using a single external capacitor, allowing the output to ramp to its nominal voltage at a controlled rate. Quiescent current is typically only 1.9 mA, and when the -5-V output is not required, a logic-enabled shutdown mode reduces current consumption to 10 µA (max). Other features include an undervoltage lockout (UVLO) circuit to prevent the power switch from turning on during start up, over-current limiting, and a 1.2-V, 125-µA reference voltage.
The TPS6735 is attractive for board level dc-dc conversion, capable of delivering more power than typical switched-capacitor converters without the complications of complex isolated dc-dc converter designs. Applications for the TPS6735 include computer peripherals, hard disk drives (HDDs), and a variety of other handheld, portable, and battery-powered designs. Designed to be pin-compatible with the MAX735, the TPS6735 is available in 8-pin DIP and SOIC packages.
Vol 18, August, 1996
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