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Features
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
Description 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 VDS 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.
Applications
Power supply for CPUs of notebook PCs that require the SpeedStep™ technique
Power supply for information appliances
General low voltage DC/DC buck regulators
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