ST ISA051V2 User Manual

STEVAL-ISA051V2

Complete DDR2/3 memory power supply controller evaluation board based on the PM6670AS

Features

■4.5 V to 36 V input voltage range

■0.9 V, ±1% voltage reference

■1.8 V (DDR2) or 1.5 V (DDR3) fixed output voltages

■0.9 V to 2.6 V adjustable output voltage

■1.237 V ±1% reference voltage available

■Very fast load transient response using constant on-time loop control

■No RSENSE current sensing using the RDS(on) of the low-side MOSFETs

■Negative current limit

■Latched OVP, UVP and thermal shutdown

■Fixed 3 ms soft-start

■Selectable pulse-skipping at light load

■Selectable no-audible (33 kHz) pulse-skip mode

■All ceramic output capacitors application supported

■Output voltage ripple compensation

Data Brief

STEVAL-ISA051V2

The device is fully compliant with system sleep states S3 and S4/S5, providing LDO output high impedance in suspend-to-RAM and tracking discharge of all outputs in suspend-to-disk.

Description

This evaluation board based on the PM6670AS device is a complete DDR2/3 power supply regulator for portable applications designed to meet JEDEC specifications. It integrates a constant on-time (COT) buck controller, a 2 Apk sink/source low dropout regulator and a 15 mA low noise buffered reference.

The COT architecture assures fast transient response supporting both polymeric and ceramic output capacitors. An embedded integrator control loop compensates the DC voltage error due to the output ripple. The 2 Apk sink/source linear regulator provides the memory termination voltage with fast load transient response.

March 2008	Rev 1	1/4
For further information contact your local STMicroelectronics sales office.		www.st.com

Circuit schematic	STEVAL-ISA051V2

1 Circuit schematic

Figure 1. Schematic

J1		VIN					J2			VDDQ																	J3	PGND	J4	PG
1								1		D3		STPS1L60A																1		1
										1		220u	2
										C4
										1		2
										C3		220u
										1		2
					R6 0
										6.8k							2		47n
			C2 10u				1u	2		R15							1		C15
					0
		1		2			L1			7.5k
					0			1											C18
		1		2						R14				R16		4R7				1n						GND TP					INT CER
			C1	10u									D2						1		2				TP1					JP5
																STPS1L60A
												1						2													680p
					8					8																			0	2
					7		3			7					3
																	STS7NF60L
					6		2			6					2															1	C16
					5		1			5					1
				Q1	STS5NF60L	2 4						4		Q2																	1	2	0
2	330k										0																				C17	0
1	R1					R4 3R3					R17
		C14	100n			1			C13	100n									VCC 100k						1			2
					0															2	100k	2				R13	100k
		1		2							0
		1	18k	2	0				1 2										R11	1	R12	1			SW1
		R2																										2		0
																									3
																									4			1
																								C22	100p
																					C21	100p	2		1
																										0
								1k5
							2														2	1
								R3														DSCG		JP2
																									6			5
						100n					18	17	16	15		14	13								4			3
																									2			1
															PG S3
		2		1	1	2				CSNS									DSCG
VCC			D1	BAT41J	R10 0C12		1		19							PM6670AS		S5			12
										PHASE									COMP
									20												11
										HGATE									MODE
									21												10
										BOOT									VSNS
									22												9
																			VOSC
									VCCLDOINVCCLGATEPGND												8				JP3			MODE
									23	VTT	VTTGND VTTSNS DDRSEL				VTTREF SGND				VREF
	C11	10u							24												7
										THPD								AVCC
					0				U1
	1	2								25	1 2 3 4 5 6														R9 18k			R8 27k		0
							C20		10u
							1		2		0											1
							C19		10u										C10		100n			C9
							1		2													2
		1		2															1		2							DDRSEL
VCC			R7	3R9			C7		10u															JP1						0
							1		2		0														6			5
							C6		10u
																									4			3
							1		2																2			1
			C5 1u
					0
		1		2
																						C8	33n								0
																										0
																					1		2
	1			1		1	1												1									1		1
J5	VCC			J9	J6	LDOIN	J7											J8										J10		J11
				VCCGND			VTT												VTTREF									AGND		AGND

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