- Two synchronous buck regulators
- Phase operation of 180°
- Fixed nominal frequency of 200 kHz: LM5642
- Fixed nominal frequency of 375 kHz: LM5642X
- LM5642 from 150 kHz synchronous switching frequency to 250 kHz and LM5642X from 200 kHz to 500 kHz
- 4.5V to 36V input range
- The shutdown current is 50μA
- Adjustable Output from 1.3V to 90% of VIN
- 0.04% (typical) line and load regulation accuracy
- Current mode control with or without sense resistors
- A separate enable/soft-start pin allows for simple sequential startup configuration.
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Can be configured for single-output parallel operation. (See.) ）
- Adjustable cycle-by-cycle current limit
- Input undervoltage lockout
- Output overvoltage latching protection
- Output undervoltage protection with delay
- Thermal shutdown
- Self-discharge when the regulator of the output capacitor is turned off
- TSSOP and eTSSOP (exposed pad) packages
illustrate
The LM5642 series includes two current mode synchronous buck regulator controllers with a 180° phase for the LM5642 at 375kHz and a normal switching frequency of 200kHz for the LM5642X.
Phase operation reduces the input RMS ripple current, which greatly reduces the input capacitance required. The switching frequency can be synchronized to the 200 kHz and 500 kHz external clock of the LM5642X between 150 kHz and the LM5642X between 250 kHz. The two switching regulator outputs can also be operated in parallel as a dual-phase, single-output regulator.
The output of each channel can be adjusted independently from 1.3V to 90% of VIN. The internal 5V rail can also be externally driven bootstrap circuit.
Current-mode feedback control guarantees excellent line and load regulation and excellent response to fast load transients with wide loop bandwidth. The current is an external current sense resistor connected in series across the top FET of the Vds or the drain of the top FET.
The LM5642 features an analog soft-start circuit that is independent of the output load and output capacitor for soft-start behavior that is more predictable and controllable than traditional soft-start circuits.
Two output overvoltage protection. A UV delay pin can also allow the IC to delay the off-time based on the output voltage event.
apply
- Embedded computer systems
- Navigation system
- Telecommunication systems
- Stb
- WebPAD
- Point-load power architecture
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