Switched Voltage Regulator IC’s Part 1

The SI9145 switchmode controller IC is ideally suited for high efficiency dc/dc converters in low input voltage systems. Operation is guaranteed down to 2.7 V, with a minimum start-up voltage of 3.0 V making the Si9145 ideal for use with NiCd, NMH, and lithium ion battery packs. A mode select pin allows the output driver polarity to be programmed allowing the device to function as a step-up or step-down converter. Features include a precision bandgap reference, a wide bandwidth error amplifier, a 2-MHz oscillator, an input voltage monitor with standby mode and a 200-mA output driver. Supply current in normal operation is typically 1.1 mA and 250 A in standby mode. The SI9145 implements conventional voltage mode control. The maximum duty cycle in boost mode can be limited by voltage on DMAX/SS pin. Frequency can be externally programmed by selection of ROSC and COSC. The SI9145 is available in both standard and lead (Pb)-free 16-pin SOIC and TSSOP packages and is specified over the industrial temperature range (-25°C to 85°C).

• 2.7-V to 7-V Input Operating Range
• Voltage-Mode PWM Control
• High-Speed, Source-Sink Output Drive (200 mA)
• Internal Oscillator (up to 2 MHz)
• Standby Mode
• 0-100% Controllable Maximum Duty-Cycle