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Features
Four synchronous buck regulators
Channel 3: Two-phase, current mode controller
4.5V to 18V input range
Built in sequential startup
Channels 1 and 2: Independent, 180° out of phase voltage mode controllers
Single soft start for channels 1 and 2
Adjustable cycle-by-cycle current limit for each channel
Adjustable reference current
Adjustable input under-voltage lockout
Output over-voltage latch protection
Output under-voltage protection with delay
Two comparator inputs for user defined protection - one with delay
Thermal shutdown
Self-discharge of output capacitors when the regulator is off
TSSOP package
Description The LM2648 consists of two current mode and two voltage mode synchronous buck regulator controllers providing 3 outputs at
a switching frequency of 300kHz.
Each pair of switching regulator controllers operate 180° out of phase. This feature reduces the input ripple RMS current,
thereby significantly reducing the required input capacitance. The two current mode regulator outputs operate as a dual-phase,
single output regulator for high current applications.
Current-mode feedback control on Channel 3 assures superior line and load regulation and wide loop bandwidth assures excellent
response to fast load transients. Channels 1 and 2 employ voltage-mode feedback control.
The LM2648 features analog soft-start circuitry that is independent of the output load and output capacitance. This makes
the soft-start behavior more predictable than traditional soft-start circuits. Sequential startup is built in and requires
a single capacitor to set the timing.
The LM2648 has over-voltage protection and under-voltage protection for all outputs. Two additional comparator inputs (analog
and logic level) are provided to shut down the IC for any user defined protection. The FAULT_DELAY pin allows delayed shut
off time for the IC during an under-voltage or PROT-IN2 fault. The LM2648 also features an adjustable UVLO feature.
Applications
Embedded Computer Systems
Interactive Games
Set-top Boxes/Home Gateways
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