Maxim Introduces PWM Step-Down Controller For DDR, DDR2, & DDR3 Memory
Maxim Integrated Products introduced the MAX17000 Quick-PWM, step-down controller for DDR, DDR2, and DDR3 memory in notebook computers. The company claims that this single-chip solution saves valuable board space by integrating a step-down controller, source/sink linear regulator, and reference buffer, thus enabling it to generate all required VDDQ, VTT, and VTTR rails. The MAX17000 is suitable for stepping-down high voltages in notebook computers.
The step-down controller supplies the VDDQ rail, providing a ±1% accurate output voltage over the line-and-load operating range. The ±2A source/sink regulator generates the memory-termination VTT rail. Featuring a ±5mV deadband, this VTT regulator reduces output capacitance requirements and sources or sinks, making it suitable for the fast-changing short loads in memory-termination applications. The VTTR reference buffer sources and sinks ±3mA, providing the reference voltage for the memory controller and devices on the memory bus.
The MAX17000 utilizes Maxim’s proprietary, Quick-PWM architecture to support wide input/output voltage ratios and provide what is described as excellent transient response, while maintaining a relatively constant switching frequency. This architecture is said to avoid the poor load-transient timing problems of fixed-frequency, current-mode PWMs, as well as the widely varying switching frequencies in conventional constant-on-time and constant-off-time PWM schemes.
This controller offers three different operating modes: a power-efficient skip mode, a low-noise forced-PWM mode, and a standby mode that supports memory when the notebook computer is in standby operation. The MAX17000 also features overvoltage, undervoltage, and thermal protection.
The MAX17000 is available in a small, 4 x 4mm, 24-pin TQFN package, and is fully specified over the -40 to +85°C extended-industrial temperature range. Prices start at $2.75 (1000-up, FOB USA).