Switching Power Supply with Linear Regulators

The 33998 is a medium-power, multi-output power supply integrated circuit that is capable of operating over a wide input voltage range, from 6.0 V up to 26.5 V with 40 V transient capability. It incorporates a sensorless current mode control step-down switching controller regulating directly to 5.0 V. The 2.6 V linear regulator uses an external pass transistor to reduce the 33998 power dissipation. The 33998 also provides a 2.6 V linear standby regulator and two 5.0 V sensor supply outputs protected by internal low-resistance LDMOS transistors.
There are two separate enable pins for the main and sensor supply outputs and standard supervisory functions such as resets with power-up reset delay. The 33998 provides proper power supply sequencing for advanced microprocessor architectures such as the Motorola MPC5xx and 683xx microprocessor families.

FEATUREs
• Operating Voltage Range 6.0 V up to 26.5 V (40 V transient)
• Step-Down Switching Regulator Output VDDH = 5.0 V @ 1400 mA (total)
• Linear Regulator with External Pass Transistor VDDL = 2.6 V @ 400 mA
• Low-Power Standby Linear Regulator VKAM = 2.6 V @ 10 mA
• Two 5.0 V @ 200 mA (typical) Sensor Supplies VREF Protected Against Short-to-Battery and Short-to-Ground with Retry Capability
• Undervoltage Shutdown on the VDDL, VDDH Outputs with Retry Capability
• Reset Signals
• Power-Up Delay
• Enable Pins for Main Supplies (EN) and Sensor Supplies (SNSEN)
• Power Sequencing for Advanced Microprocessor Architectures
• SOIC-24WB Package