Abstract: The emergence and explosive growth of new terminal applications continue to drive the demand for data storage, prompting the continuous iteration and replacement of SDRAM, making efficient and stable power management chips increasingly important. IVS introduces the highly integrated, ultra-high power density synchronous full-switching mode converters IS6630A/C/D, which achieve three output voltages in an ultra-small form factor, providing a comprehensive DDR power supply solution. This offers a more efficient and lower-power operating environment for end applications.

Solution Overview

The IS6630A/C/D full-switching mode converters, housed in a compact 3mm * 3mm * 0.85mm QFN package, provide a complete, ultra-high power density integrated power supply solution for SDRAM. They include a fixed LDO output, support a wide input voltage range (4.5V~22V), and deliver up to 10A continuous output current. Product features are as follows:

**Figure 1 IS6630A/C/D Full-Switching Mode Converter**

• IS6630A features fully integrated power rails: VDDQ (BUCK), VTT (LDO), VPP (LDO), and VTTREF. IS6603C/D features fully integrated power rails: VDDQ (LDO), VDD1 (LDO), VDD2 (BUCK).
• Utilizes TCOT^TM control mode for fast transient response.
• 10A continuous output current.
• Switching frequency: 500kHz / 700kHz.
• Excellent load and line regulation, with accuracy up to 1%.
• Efficiency can exceed 92% across the load range under conditions of VIN=12V, VOUT=1.2V.
• Supports internal soft-start and programmable valley current limit.
• Internally integrates protection features including OCP, NOCP, OVP, UVLO, OTP.

Product Advantages

1. Simple Control Loop, Extremely Fast Transient Response

   The IS6630A/C/D uses IVS's patented TCOT^TM control mode, which directly compares FB with REF to adjust the output voltage. The feedback loop does not require complex compensation, eliminating RC network delay. Simultaneously, the control loop can respond quickly to output voltage changes without waiting for the clock signal, thus eliminating clock delay. Only a small amount of ceramic capacitors are needed to achieve extremely fast transient response speed. The schematic below compares the transient response of current-mode control and COT control mode, showing COT mode is significantly faster.

   
   Figure 2 Schematic Comparison of Transient Response: Current-Mode Control vs. COT Control Mode

2. RAMP Slope Compensation, Supports All-Ceramic Output Capacitors

   The IS6630A/C/D integrates a slope compensation network, the RAMP signal, within the chip. This signal is superimposed on the FB pin, simulating the resistive ripple effect of ESR to prevent "multi-pulse oscillation" instability. The IS6630A/C/D can operate stably using only ceramic capacitors, saving space and reducing cost.

3. Built-in Integrator for High Output Voltage Accuracy

   The IS6630A/C/D incorporates a slow digital integrator that continuously corrects the reference voltage REF, thereby improving output voltage accuracy and eliminating the half-ripple deviation inherent in COT. This digital integrator also gives the IS6630A/C/D good linearity, achieving output voltage accuracy as high as ±1% under different load currents and input voltages.

   
   Figure 3 IS6630A Line Regulation Curve
   
   Figure 4 IS6630A Load Regulation Curve

4. High Efficiency, Low Power Consumption

   Thanks to optimized integrated MOSFETs with low on-resistance and driving circuitry, the IS6630A/C/D achieves efficiency up to 92% under VIN=12V, VOUT=1.2V conditions. Under light load conditions, the chip operates in fixed DCM mode, further reducing power consumption and improving overall efficiency. Additionally, the IC features USM (Ultrasonic Mode): compared to standard DCM mode, it triggers the low-side MOSFET one extra time, significantly increasing the switching frequency. This prevents the light-load switching frequency from falling into the audible human ear frequency range during DCM operation, eliminating noticeable audible noise.

   
   Figure 5 IS6630A/C/D Efficiency Curve Schematic

Series Selection

The IS6630A/C/D supports an ambient temperature range of -40°C to +125°C, suitable for applications like laptops, servers, and data centers requiring high data transfer rates or wide output voltage ranges. The IS6630 series offers various three-output voltage options, aiding terminal application engineers in designing diverse solutions for different scenarios.

Figure 6 IS6630A/C/D Specific Application Classification and Required Voltage Table

Application Example

The input voltage for a laptop motherboard is determined by the battery specification and adapter. Typically, a laptop adapter voltage is 19V, and batteries can be 3S (9V-13.2V) or 4S (12V-17.6V). Taking a laptop motherboard powered by a 4S battery as an example, here is an application design instance for the IS6630A powering DDR4:

Application Conditions: VIN=12V~19V, VOUT=1.2V (Imax=10A), VTT=0.6V (Imax=1A), VPP=2.5V (Imax=1A), Load Step: 0A~7A & 3A~10A, PKPK of VOUT ≤ 120mV (±5%).

First, select the switching frequency. The IS6630A offers 500kHz and 700kHz; generally, 700kHz is recommended.

Next, determine the inductor value. The inductor current ripple is typically set between 20%~40% of the full-load output current. For this application, full-load current is 10A, so the ripple range is 2A~4A. Using the formula $\mathrm{\Delta}IL = \frac{VIN - VOUT}{L} \ast T_{ON}$, with VOUT=1.2V and Fsw=700kHz, calculations show: for VIN=12V, inductor range is 0.39uH~0.77uH; for VIN=19V, inductor range is 0.4uH~0.8uH. A 0.68uH inductor is selected.

Finally, using the design tool provided by IVS, appropriate output capacitors are selected for VDDQ, VTT, and VPP. Here, VDDQ uses six 22uF ceramic capacitors. VTT uses one 4.7uF and one 22uF ceramic capacitor in parallel. VPP uses one 1uF and one 47uF ceramic capacitor in parallel. With this, the key parameters for this application are determined. The corresponding measured waveforms are shown below.

Load Transient: VIN=19V VOUT=1.2V, LOAD 3A~10A 1A/us, PKPK of VOUT=66mV

Vo Ripple: VIN=19V VOUT=1.2V, LOAD=10A, PKPK of VOUT=10mV

JITTER of LOAD=5A

Power on by EN2

Power off by EN2

【About IVS】

Dongguan IVS Electronics Co., Ltd. was established in May 2016, located in Songshan Lake, Dongguan. It possesses a professional technical team, adheres to independent forward design, and is dedicated to designing high-performance, low-voltage, high-current power supply chips. Addressing the domestic gap in the CPU power supply field, the company has launched a full set of solutions, breaking the foreign chip monopoly. Products include switching regulators, multi-phase controllers, smart power stages, and power modules, widely applicable to markets such as servers, computers, communications, and consumer electronics.