Features and Benefits
- 4.5V to 23V Input Supply Range
- 0 to 18V Output Voltage Range (Up to 10A)
- Adjustable Lossless Foldback Current Limit
- Adjustable 100kHz to 600kHz Switching Frequency
- Optional Synchronization
- Clock Output for Master/Slave Synchronization
- 4 x 90° Out-of-Phase Step-Down Converters (Using Two Controllers, Figure 7)
- Prebias Startup (MAX1875A/MAX1876A)
- Power Sequencing (MAX1858A)
- RST-bar Output with 140ms Minimum Delay (MAX1858A/MAX1876A)
- Fixed-Frequency Pulse-Width Modulation (PWM) Operation
The MAX1858A/MAX1875A/MAX1876A dual, synchronized, step-down controllers generate two outputs from input supplies ranging from 4.5V to 23V. Each output is adjustable from sub-1V to 18V and supports loads of 10A or higher. Input voltage ripple and total RMS input ripple current are reduced by synchronized 180° out-of-phase operation.
The switching frequency is adjustable from 100kHz to 600kHz with an external resistor. Alternatively, the controller can be synchronized to an external clock generated by another MAX1858A/MAX1875A/MAX1876A or a system clock. One MAX1858A/MAX1875A/MAX1876A can be set to generate an in-phase, or 90° out-of-phase, clock signal for synchronization with additional controllers. This allows two controllers to operate either as an interleaved two- or four-phase system with each output shifted by 90°. The MAX1858A/MAX1875A/MAX1876A feature soft-start. The MAX1858A also features first-on/last-off power sequencing and soft-stop.
The MAX1858A/MAX1875A/MAX1876A eliminate the need for current-sense resistors by utilizing the low-side MOSFET's on-resistance as a current-sense element. This protects the DC-DC components from damage during output-overload conditions or output short-circuit faults without requiring a current-sense resistor. Adjustable foldback current limit reduces power dissipation during short-circuit conditions. The MAX1858A/MAX1876A include a power-on reset (POR) output to signal the system when both outputs reach regulation.
The MAX1858A/MAX1875A/MAX1876A ensure that the output voltage does not swing negative when the input power is removed or when EN is driven low. The MAX1875A/MAX1876A also allow prebias startup without discharging the output.
The MAX1858A/MAX1875A/MAX1876A are available in a 24-pin QSOP package. Use the MAX1875 evaluation kit or the MAX1858 evaluation kit to evaluate the MAX1858A/MAX1875A/MAX1876A.
- Broadband Routers
- Desknote Computers
- DSP, ASIC, and FPGA Power Supplies
- Network-Power Supplies
- Set-Top Boxes
- Telecom Power Supplies
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
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