Non-Isolated Point-of-Load Solutions for Elkhard Lake in Industrial PC Applications

Non-Isolated Point-of-Load Solutions for Elkhart Lake in Industrial PC Applications

Industrial computers serve to improve business continuity and streamline industrial process control. Advanced processors and platforms, such as the Intel® Elkhart Lake micro-achitecture, need point-of-load (POL) solutions for memory, low-power CPU rails, and 3.3 V and 5 V rail requirements from an array of rechargeable batteries or a 12 V input bus. This document intends to highlight DC/DC converters from Texas Instruments that provide performance power management solutions to extend battery life while addressing Elkhart Lake platform power requirements. For specific information about Intel processors and their power requirements, log on to the Intel Resource and Design Center. Contact TI for information about multiphase controllers and power stages designed specifically for the Intel Mobile Voltage Positioning (IMVP) requirements.

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1 Suggested Elkhart Lake Point-of-Load Solutions

Table 1 highlights the latest POL DC/DC converters with integrated MOSFETs and controllers suitable for Elkhart Lake applications. The suggested devices are selected to accommodate different input voltage and control mode requirements over a wide range of output current. The featured devices in the left-hand column accommodate a maximum input voltage of 22V or greater, and are designed to achieve fast load-transient response with an adaptive on-time control mode, high light and full-load efficiency, and low quiescent current. Several devices include an integrated programmable voltage identification (VID) supporting the processor's adaptive voltage requirements. The alternate devices in the right-hand column employ a fixed-frequency control mode with frequency synchronization useful in noise-sensitive industrial applications. If VID is required with alternative devices, consider the LM10011 VID voltage programmer in addition to the converter's resistor divider network.

Table 1. Suggested DC/DC Controllers and Converters for Elkhart Lake

Featured Device⁽²⁾	Type	Current	Rail	Note	Alternate Device⁽¹⁾
TPS51285A	Dual Controller + LDOs	≤20A & 100mA LDO	V5	System Power	TPS51220A
TPS51285A	Dual Controller + LDOs	≤20A & 100mA LDO	V3P3	System Power	TPS51220A
TPS51393	Converter + LDO	≤8A & 100mA LDO	V5	System power	TPS54824
TPS51395	Converter + LDO	≤8A & 100mA LDO	V3P3	System power	TPS54824
TPS51215A	Controller	≤35A	V_{CCIN_AUX}	I/O power, 2-bit VID (0V support)	-
TPS51371	Converter	≤ 6.5A	VCCIO, V1P05, V_NN	Optional bypass power, 2-bit VID	LM43600
General Purpose DC/DC Converters
-	Converter	≤25A	Various	I/O	TPS543B20
TPS51367	Converter	≤12A	Various	I/O	TPS54A24
TPS51396A	Converter	≤8A	Various	I/O	TPS54824
TPS566335	Converter	≤6A	Various	I/O, V1P8, V_PP	TPS54824
TPS56339	Converter	≤3A	Various	I/O	TPS54424
TPS62175	Converter	≤0.5A	V1P2, various	I/O	LM43600
DDR Memory Power Solutions
TPS51486	Multi-Rail PMIC	≤8A	V_DDQ	DDR4 Memory	TPS65295
		≤1A	V_PP
		±1A	V_TT
		10mA	V_{TT_REF}
TPS51487X	Multi-Rail PMIC	≤8A	V_DD1	LPDDR4/X Memory	TPS65296
		≤1A	V_DD2
		≤1.5A	V_{DDQ_TX}
TPS51716	Multi-Rail Controller	≤20A	V_DDQ	DDR4 Memory	Consider I/O devices
		±2A	V_TT
		10mA	V_{TT_REF}
TPS51206	LDO	±2A	V_TT	DDR4 Memory	-
TPS51206	LDO	10mA	V_{TT_REF}	DDR4 Memory	-

(1) Alternative devices support input voltages up to around 17-V and feature fixed-frequency current-mode control.

(2) Note: Some 24-V rated devices require Mysecure access to download the datasheet. Click on the device link to request access. Users will require their my.ti.com account information.

2 Light Load Efficiency and Low Quiescent Current

The POL regulators generating low voltages from an array of batteries must employ an energy-saving pulse-skipping technique now referred to as Eco-Mode. The inductor current in a synchronous-buck converter is a triangle wave. As the output current decreases from a heavy-load condition, the inductor current is reduced and the rippled valley of the triangle wave eventually touches the zero level at the boundary between continuous conduction-mode (CCM) and DCM. With Eco-Mode, the rectifying MOSFET is turned off when the converter detects zero current in the inductor. As the load current further decreases, the on-time is held nearly constant so that the off-time is extended, and the switching frequency is reduced to maintain regulation. As a result, the power MOSFETs and inductor are idle for longer time periods and conduction losses are greatly reduced. The point at which the DC/DC converter enters the light-load efficiency mode is shown in Equation 1.

DC/DC converters and controllers with low quiescent current will have improved light-load efficiency performance and extended battery run-time, since less power is dissipated within the IC. The TPS51285A features Ultra Low Quiescent current (ULQ) of 25-uA for longer battery life in system stand-by mode. Figure 1 shows 90% efficiency with 7.4-V input and 5-V output at 1-mA, illustrating the combined affects of Eco-Mode and ULQ.

Equation 1.

$I O U T (L L) = \frac{1}{2} x L x F = (V I N - V O U T) x \frac{V O U T}{V I N}$

Figure 1. TPS51285A Efficiency plot with Eco-Mode^TM and ULQ^TM TPS51215A TPS51285A TPS566335 TPS51371 TPS51486 TPS51367 TPS51372 TPS51285A eff.jpg