STMicroelectronics STEVAL-ISA050V1

Overview

STEVAL-ISA050V1 from STMicroelectronics is an evaluation board for the PM6641 monolithic voltage regulator module, designed to validate DDR2/3 memory and chipset power delivery in ultra-mobile PC (UMPC) systems. It implements three independent adjustable buck converters (1.8 V, 1.5 V, 1.05 V), a ±2 A LDO for VTT termination, and a low-noise ±15 mA VTTREF buffer, all operating from a 2.7–5.5 V input.

For engineers reviewing the STEVAL-ISA050V1 datasheet, STEVAL-ISA050V1 pinout, STEVAL-ISA050V1 application, or STEVAL-ISA050V1 equivalent, this board enables functional validation of S0–S5 state compliance, out-of-phase switching, pulse-skipping efficiency at light load, and tracking/non-tracking soft-end discharge behavior for DDR2/3 termination rails.

Technical Context

The STEVAL-ISA050V1 implements the full PM6641 reference design per ST's Doc ID 13510 Rev 3, including all three synchronous buck regulators with current-mode control, integrated high-side/low-side MOSFETs (R_DS(on) = 90–220 mΩ), and dedicated VTT/VTTREF circuitry. It supports selectable switching frequency (500–825 kHz) via SET_SWF and phase interleaving via SET_PH1.

Board-level features include discrete soft-start capacitor connections (SS_1S8/SS_1S5/SS_1S05), open-drain Power Good signals (PG_1S8/PG_1S5/PG_1S05), DSCG-controlled tracking discharge, and EN_VTT/EN_1S8 logic for S3/S5 state sequencing - all verified using the PM6641EVAL platform referenced in Figure 21–22 of the datasheet.

Key Specifications

Availability

STEVAL-ISA050V1 is available at Aetrix Electronics and suitable for DDR2/3 memory validation, UMPC power architecture prototyping, and portable system S3/S5 state compliance testing requiring stable component supply and documented reference implementation.

Supply support for STEVAL-ISA050V1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, microcontrollers, and analog/mixed-signal ICs for industrial, automotive, and consumer applications.

The PM6641 product line targets space-constrained portable systems requiring multi-rail DDR2/3 and chipset regulation with S0–S5 power state awareness - optimized for ultra-mobile PCs and handheld devices per its application focus in Section 1 and Figure 9.

FAQ

What is the primary function of the STEVAL-ISA050V1 evaluation board?

The STEVAL-ISA050V1 is a fully assembled demonstration board for the PM6641 voltage regulator IC. Its purpose is to validate the complete power solution for DDR2/3 memory and chipset supplies in ultra-mobile PC designs, including output sequencing, S0–S5 state transitions, soft-start/soft-end behavior, and ripple/noise performance under real load conditions as shown in Figures 3–22 of Doc ID 13510 Rev 3.

Does STEVAL-ISA050V1 support both DDR2 and DDR3 termination voltage (VTT) configurations?

Yes. The board implements the PM6641's dual-mode VTT LDO, delivering ±0.9 V for DDR2 (with VLDOIN = 1.8 V) and ±0.75 V for DDR3 (with VLDOIN = 1.5 V), as specified in Table 6. It also provides the buffered VTTREF output at 0.9 V with ±2% accuracy relative to VOUT_1S8/2, enabling precise termination reference for either memory standard.

How is phase interleaving configured on the STEVAL-ISA050V1?

Phase interleaving is controlled via the SET_PH1 pin (Pin 39), which configures the relative timing offset between the three buck regulators. As described in Section 7.9, connecting SET_PH1 to AGND, AVCC, or leaving it floating selects 0°, 120°, or 180° phase shift respectively - allowing optimization of input/output ripple and EMI performance without external synchronization circuitry.

Can the STEVAL-ISA050V1 be used to evaluate light-load efficiency behavior?

Yes. The board demonstrates the PM6641's pulse-skipping mode at light load, confirmed in Figure 13 (efficiency vs. load) and Section 7.4. With no load, the IC automatically enters pulse-skipping to maintain regulation while minimizing quiescent current - achieving >75% efficiency down to 1 mA load across all rails, as measured on the PM6641EVAL platform referenced in the datasheet's note on page 17.