DESCRIPTION

TheLTM4643 is a quad DC/DC step-down μModule (power module) regulator with 3A per output. Outputs can be paralleled in an array for up to 12A capability. Included in the package are the switching controllers, power FETs, inductors and support components. Operating over an input voltage range of 4V to 20V or 2.375V to 20V with an external bias supply, the LTM4643 supports an output voltage range of 0.6V to 3.3V each set by a single external resistor. Its high efficiency design delivers 3A continuous output current per channel. Only bulk input and output capacitors are needed.

Fault protection features include overvoltage, overcurrent and overtemperature protection. The LTM4643 is offered in a 9mm ×15mm × 1.82mm LGA and 9mm × 15mm × 2.42mm BGA packages with SnPb (BGA) or RoHS compli-ant terminal finish.

 

CARACTÉRISTIQUES

Quad Output Step-Down μModule® Regulator with 3A per Output

Wide Input Voltage Range: 4V to 20V

2.375V to 20V with External Bias

0.6V to 3.3V Output Voltage

3A DC Output Current Each Channel

±1,5% Régulation de la tension de sortie totale

Contrôle du mode courant, réponse transitoire rapide

Mise en parallèle pour un courant de sortie plus élevé

Suivi de la tension de sortie

Diode de détection de température interne Sortie

Synchronisation de la fréquence externe

Protection contre les surtensions, le courant et la température

9mm × 15mm × 1.82mm LGA and 9mm × 15mm ×2.42mm BGA Packages

 

CANDIDATURES

FPGAs, GPUs and ASICs Applications

PCIe and Backside PCB Mounting

 

FONCTIONNEMENT

The LTM4643 is a quad output standalone non-isolated switch mode DC/DC power supply in 9mm × 15mm × 1.82mm ultrathin package. It has four separate regula-tor channels with each of them capable of delivering up to 3A continuous output current with few external input and output capacitors. Each regulator provides precisely regulated output voltage programmable from 0.6V to 3.3V via a single external resistor over 4V to 20V input voltage range. With an external bias voltage, this module can operate from an input voltage as low as 2.375V.

The LTM4643 integrates four separate constant frequency controlled on-time valley current mode regulators, power MOSFETs, inductors, and other supporting discrete com-ponents. The typical switching frequency is set to 1.2MHz. For switching noise-sensitive applications, the μModule regulator can be externally synchronized to a clock from 850kHz to 1.5MHz.

With current mode control and internal feedback loop compensation, the LTM4643 module has sufficient stabil-ity margins and good transient performance with a wide range of output capacitors, even with all ceramic output capacitors.

Current mode control provides the flexibility of paralleling any of the separate regulator channels with accurate cur-rent sharing. With a built-in clock interleaving between regulator channels, the LTM4643 can easily be configured for 2+2, 3+1 or 4 channels parallel operation providing more design flexibility for multirail POL applications. Fur-thermore, the LTM4643 has CLKIN and CLKOUT pins for frequency synchronization or polyphasing multiple devices which allow up to 8 phases cascaded to run simultaneously.

Current mode control also provides cycle-by-cycle fast current monitoring. Foldback current limiting is provided in an overcurrent condition to reduce the inductor valley current to approximately 40% of the original value when VFB drops. An internal overvoltage and undervoltage comparators pull the open-drain PGOOD output low if the output feedback voltage exits a ±10% window around the regulation point. Continuous conduction mode (CCM) operation is forced during OV and UV conditions except during start-up when the TRACK pin is ramping up to 0.6V.

Pulling the RUN pin below 1.1V forces the controller into its shutdown state, turning off both power MOSFETs and most of the internal control circuitry. At light load cur-rents, discontinuous conduction mode (DCM) operation can be enabled to achieve higher efficiency compared to continuous conduction mode (CCM) by setting the MODE pin to SGND. The TRACK/SS pin is used for power supply tracking and soft-start programming.

A temperature diode is included inside the module to moni-tor the temperature of the module.