Intersil Powers DDR Memory

Intersil Powers DDR Memory

Intersil’s Power Supply Solutions for DDR Memory

Complete Solutions for V_DD and V_TT	V_IN	Comments	Pkg/Pins
ISL6530, ISL6531	+5V	With V_REF output	SOIC-24, QFN-32
ISL6227	4.5V to 24V	Automatic light/heavy load selection	SSOP-28
ISL6532, ISL6532A	2.5V to 5V, 12V	Includes standby LDO, ACPI compliant	QFN-20/28
ISL6534	3.3V to 12V, 5V	Includes standby LDO	TSSOP-24, QFN-32
ISL6539	4.5V to 15V	Dual PWM with DDR mode	SSOP-28
Single Solutions for V_DD or V_TT	V_IN	Comments	Pkg/Pins
ISL6520, ISL6520A	+5V	Small, low cost	SOIC-8
ISL6522, ISL6522A	5V or 12V, 12V	1%/0.5% regulation	SOIC-14, QFN-16, TSSOP-14
ISL6527, ISL6527A	3.3V to 5V	External ref input	SOIC-14, QFN-16

TYPICAL DDR MEMORY POWER SOLUTION

Double Data Rate (DDR) Synchronous Dynamic Random Access Memory (SDRAM) is today’s memory of choice for many applications. As its name implies, DDR SDRAM operates at a rate double that of previous-generation Random Access Memory (RAM). While previous SDRAM allowed one memory access per clock cycle, DDR SDRAM allows two memory accesses per cycle. Thus, data handling is faster and more efficient.

In addition to the dramatic increase in data rate, DDR memory requires less power because it operates from a lower source voltage, 2.5V as compared to 3.3V of older SDRAM.

To utilize DDR memory, special power considerations have to be addressed. DDR memory requires three highly regulated voltages referred to as V_DDQ, V_TT and V_REF. V_DDQ is the main high-current supply. V_TT is a memory bus termination voltage that is half V_DDQ (V_DDQ/2). V_REF is a low-power reference voltage that tracks at half V_DDQ and to which V_TT is compared, where V_TT = V_REF.

For DDR, the V_DDQ supply is 2.5V and produces a high current to power the DDR memory ICs along with the clock synthesizer and the MCH IC core. Because of this, the V_DDQ supply is usually a synchronous buck, PWM switching regulator. The V_TT supply must source and sink current on the data lines. This is also best handled by a synchronous buck regulator since linear regulators and standard bucks cannot sink current.

Intersil has worked closely with industry chipset makers and DDR memory manufacturers to provide power solutions that supply all of the required voltages along with a full range of protection features. What’s more, Intersil has looked for opportunities to add value beyond the basic DDR memory power requirements. In so doing, Intersil now offers a selection of DDR memory power ICs that offer very high integration in small packages.