In recent years, new business models such as cloud computing and remote services have driven ever-increasing demands for data storage and transmission. SDRAM, as an upgrade to DRAM, is evolving towards higher External Data Transfer Rates, more advanced address/command, and Control Bus Topology architectures.

To ensure SDRAM achieves higher transmission rates, stable and efficient power supply is an essential component. Today's product development imposes increasingly stringent requirements on power supply chips: higher stability, lower power consumption, smaller footprint, and the need for at least 2 power supply rails.

Taking DDR4 as an example, it requires 3 power rails: VDDQ (1.2V) requiring relatively high current, and VTT (0.6V) and VPP (2.5V) requiring smaller currents. Traditional power supply solutions typically use one BUCK converter and two LDOs for power delivery, but this approach has clear disadvantages: large space occupation and numerous required ICs and peripheral components.

Integrated DDR Power Supply Solution

Addressing this market demand, IVS independently developed and launched the IS6630A/C/D series — fully switched-mode converters with a maximum load capacity of 10A, containing fixed LDO outputs, supporting fully integrated DDR power supply solutions. This power solution highly integrates the aforementioned requirement for three DDR power rails into a single chip housed in a compact 3mm * 3mm * 0.85mm QFN package, achieving an integrated DDR power supply solution while occupying minimal space.

Left: IS6630A Evaluation Board, Right: Chip 3D Schematic

Using the IS6630A as an example, since it internally integrates one BUCK converter (VDDQ), two LDOs (VTT, VPP), and a buffered low-noise reference output (VTTREF) power channel, it can provide high-power-density integrated power solutions for DDR4/DDR3/DDR3L respectively. That is, a single IS6630A can satisfy the three power rails required for DDR4 or the two power rails required for DDR3/DDR3L. Furthermore, the outputs of these three power rails only require a small number of ceramic capacitors as output capacitors, further saving PCB space and required components, enabling an ultra-compact board design.

The IS6630A only requires the provision of three input supplies (VIN, VPPIN, VCC) and enable signals EN1, EN2 to operate normally. The BUCK converter VDDQ can provide up to 10A of continuous current with an input voltage (VIN) range of 4.5V~22V and an output voltage (VDDQ) range of 0.6V~3.3V, boasting extremely high power density. VPPIN is the input voltage for the VPP LDO, supporting an input range of 2.6V~3.3V with a fixed 2.5V output. This LDO output requires only a single 22uF ceramic capacitor to provide 1A of continuous current. The input voltage for the VTT LDO is the BUCK converter's output VDDQ. The VTTREF (buffered low-noise reference output) enables VTT to accurately track VDDQ/2, fixing its output voltage at VDDQ/2. Its output also requires only a single 22uF ceramic capacitor to sink or source 1A of continuous current.

Figure 4 Typical Application Circuit Diagram for IS6630A

Similar to the IS6630A, the IS6630C and IS6630D internally integrate three power rails, providing high-power-density integrated power solutions for LPDDR5 and LPDDR4X respectively.

Figure 5 IS6630A/C/D Specific Application Categories and Required Voltage Table

Fast Transient Response and High Voltage Accuracy

The IS6630A/C/D successfully integrates three output voltage rails within an ultra-small footprint while delivering excellent performance. Its BUCK converter employs IVS's patented TCOT™ control mode, enabling fast transient response across a wide input voltage range with only a small number of ceramic output capacitors. Simultaneously, outstanding load and line regulation achieve output voltage accuracy up to ±1% under varying load currents and input voltages.

Figure 6 Transient Response Diagram for IS6630A/C/D Figure 7 Load Regulation Curve for IS6630A/C/D Figure 8 Line Regulation Curve for IS6630A/C/D

High Efficiency, Low Power Consumption

Benefiting from low MOSFET on-resistance and optimized drive circuitry, the IS6630A/C/D achieves efficiency up to 92% under conditions of VIN=12V, VOUT=1.2V. Under light load conditions, the chip operates in fixed DCM (Discontinuous Conduction Mode), further reducing chip power consumption and improving overall operational efficiency. However, in DCM mode, the switching frequency falls within the human audible range, potentially generating audible noise at higher energy levels. To address this, this chip series employs the USM (Ultrasonic Mode) based on DCM operation. Compared to DCM, when operating in USM mode, the low-side MOSFET can be turned on an additional time per cycle, increasing the switching frequency beyond the human audible range without significantly reducing efficiency.

Figure 9 Efficiency Curve Diagram for IS6630A/C/D

As a fully integrated DDR power supply solution, the IS6630A/C/D is primarily applied in industries requiring high data transfer rates and/or wide output voltage ranges, such as laptops and data centers. It balances high efficiency and high performance while offering a smaller application footprint, matching mainstream market demands and actively empowering DDR industry development.

Contact Email: sales@innovisionsemi.com