DESCRIPTION

The LTM®4644/LTM4644-1 is a quad DC/DC step-down µModule (micromodule) regulator with 4A per output. Outputs can be paralleled in an array for up to 16A capability. Included in the package are the switching controllers, powerFETs, inductorsand support components. Operating over an input voltage range of 4V to 14V or 2.375V to 14V with an external bias supply, the LTM4644/LTM4644-1 supports an output voltage range of 0.6V to 5.5V. Its high efficiency design delivers 4A continuous (5A peak) output current per channel. Only bulk input and output capacitors are needed.

 

FEATURES

Quad Output Step-Down µModule® Regulator with 4A per Output

Wide Input Voltage Range: 4V to 14V

2.375V to 14V with External Bias

0.6V to 5.5V Output Voltage

4A DC, 5A Peak Output Current Each Channel

Up to 5.5W Power Dissipation (TA = 60°C, 200 LFM, No Heat Sink)

±1.5% Total Output Voltage Regulation

Current Mode Control, Fast Transient Response

Parallelable for Higher Output Current

Output Voltage Tracking

Internal Temperature Sensing Diode Output

External Frequency Synchronization

Overvoltage, Current and Temperature Protection

9mm × 15mm × 5.01mm BGA Package

 

APPLICATIONS

Multirail Point of Load Regulation

FPGAs, DSPs and ASICs Applications

 

ELECTRICAL CHARACTERISTICS

The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25℃ (Note 2). VIN = 12V, per the typical application.

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

Note 2: The LTM4644E/LTM4644E-1 is tested under pulsed load conditions such that TJ ≈ TA. The LTM4644E/LTM4644-1 is guaranteed to meet performance specifications over the 0℃ to 125℃ internal operating temperature range. Specifications over the full –40℃ to 125℃ internal operating temperature range are assured by design, characterization and correlation with statistical process controls. The LTM4644I/LTM4644I-1 is guaranteed to meet specifications over the full –40℃ to 125℃ internal operating temperature range. The LTM4644MP/LTM4644MP-1 is tested and guaranteed over full –55℃ to 125℃ internal operating temperature range. Note that the maximum ambient temperature consistent with these specifications is determined by specific operating conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors.

Note 3: 100% tested at wafer level.

Note 4: See output current derating curves for different VIN, VOUT and TA.

Note 5: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125℃ when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability.

 

APPLICATIONS INFORMATION

TYPICAL APPLICATION:4V to 14V Input, Quad 0.9V, 1V, 1.2V and 1.5V Output DC/DC µModule Regulator. TA = 60℃, 200LFM, NO HEAT SINK

Within the LTM4644, be aware there are multiple power devices and components dissipating power, with a consequence that the thermal resistances relative to different junctions of components or die are not exactly linear with respect to total package power loss. To reconcile this complication without sacrificing modeling simplicity- but also, not ignoring practical realities—an approach has been taken using FEA software modeling along with laboratory testing in a controlled-environment chamber to reasonably define and correlate the thermal resistance values supplied in this data sheet: (1) Initially, FEA software is used to accurately build the mechanical geometry of the LTM4644 and the specified PCB with all of the correct material coefficients along with accurate power loss source definitions; (2) this model simulates a softwaredefined JEDEC environment consistent with JESD 51-12  to predict power loss heat flow and temperature readings at different interfaces that enable the calculation of the JEDEC-defined thermal resistance values; (3) the model and FEA software is used to evaluate the LTM4644 with heat sink and airflow; (4) having solved for and analyzed these thermal resistance values and simulated various operating conditions in the software model, a thorough laboratory evaluation replicates the simulated conditions with thermocouples within a controlled-environment chamber while operating the device at the same power loss as that which was simulated. An outcome of this process and due diligence yields the set of derating curves shown in this data sheet.