LM2633  Product Folder

The LM2633 is a feature-rich IC that combines three regulator controllers - two current mode synchronous buck regulator controllers and a linear regulator controller.

The two switching regulator controllers operate 180° out of phase. This feature reduces the input ripple RMS current, resulting in a smaller input filter.

The first switching controller (Channel 1) features an Intel mobile CPU compatible precision 5-bit digital-to-analog converter which programs the output voltage from 0.925V to 2.00V. It is also compatible with the dynamic VID requirements. The second switching controller (Channel 2) is adjustable between 1.25V to 6.0V.

Use of synchronous rectification and pulse-skip operation at light load achieves high efficiency over a wide load range. Fixed-frequency operation can be obtained by disabling the pulse-skip mode.

Current-mode feedback control assures excellent line and load regulation and a wide loop bandwidth for good response to fast load transient events. Current mode control is achieved through sensing the Vds of the top FET and thus an external sense resistor is not necessary.

A power good signal is available to indicate the general health of the output voltages.

A unique feature is the analog soft-start for the switching controllers is independent of the slew rate of the input voltage. This will make the soft start behavior more predictable and controllable. An internal 5V rail is available externally for boot-strap circuitry (only) when no 5V is available from other sources.

Current limit for either of the two switching channels is achieved through sensing the top FET V_DS and the value is adjustable. The two switching controllers have under-voltage and over-voltage latch protections, and the linear regulator has under-voltage latch protection. Under-voltage latch can be disabled or delayed by a programmable amount of time.

The input voltage for the switching channels ranges from 5V to 30V, which makes possible the choice of different battery chemistries and options.

GENERAL

• Three regulated output voltages
• 4.5V to 30V input range
• Power good function
• Input under-voltage lockout
• Thermal shutdown
• Tiny TSSOP package

SWITCHING SECTION

• Two channels operating 180° out of phase
• Separate on/off control for each channel
• Current mode control without sense resistor
• Skip-mode operation available
• Adjustable cycle-by-cycle current limit
• Negative current limit
• Analog soft start independent of input voltage slew rate
• Power ground pins separate
• Output UVP and OVP
• Programmable output UVP delay
• 250kHz switching frequency (for Vin < 17V)
• Channel 1 output from 0.925V to 2.00V
• ±1.5% DAC accuracy from 0°C to 125°C
• ±1.7% initial tolerance for Channel 2
• Dynamic VID change ready
• Power good flags VID changes
• Channel 2 output from 1.3V to 6.0V

LINEAR SECTION

• Output voltage adjustable
• 50mA maximum driving current
• Output UVP
• ±2% initial tolerance

• Power supply for CPUs of notebook PCs that require the SpeedStep™ technique
• Power supply for information appliances
• General low voltage DC/DC buck regulators