ISL8026

The ISL8026 is a highly efficient, monolithic, synchronous step-down DC/DC converters that can deliver 6A of continuous output current from a 2.5V to 5.5V input supply. The device uses current mode control architecture to deliver a very low duty cycle operation at high frequency with fast transient response and excellent loop stability. The ISL8026 integrates a very low ON-resistance P-channel (36mΩ) high-side FET and N-channel (13mΩ) low-side FET to maximize efficiency and minimize external component count. The 100% duty-cycle operation allows less than 180mV dropout voltage at 6A output current. The operation frequency of the Pulse-width Modulator (PWM) is adjustable from 500kHz to 4MHz. The default switching frequency, which is set by connecting the FS pin high, is 1MHz for the ISL8026 and 2MHz for the ISL8026A. The ISL8026 can be configured for discontinuous or forced continuous operation at light load. Forced continuous operation reduces noise and RF interference, while discontinuous mode provides higher efficiency by reducing switching losses at light loads. Fault protection is provided by internal hiccup mode current limiting during short-circuit and overcurrent conditions. Other protection, such as overvoltage and over-temperature, are also integrated into the device. A power-good output voltage monitor indicates when the output is in regulation. The ISL8026 offers a 1ms Power-Good (PG) timer at power-up. When in shutdown, the ISL8026 discharges the output capacitor through an internal soft-stop switch. Other features include internal fixed or adjustable soft-start and internal/external compensation.

Applications 

• DC/DC POL modules 

• μC/µP, FPGA and DSP power 

• Video processor/SOC power 

• Li-ion battery powered devices 

• Routers and switchers 

• Portable instruments 

• Test and measurement systems 

• Industrial PCs

Key Features:

The Sandler State-Space Average VRM model (SSAM) can be used for both frequency and time domain analyses:

• This model is designed to support true end-to-end power integrity simulation and modeling using Keysight ADS.

• VRM models provide small signal load ripple and large signal VRM switching ripple.

• Large signal analysis, including assessing large signal effects

• Small signal analysis

• Harmonic balance simulation

• Transient analysis

• AC analysis

• Phase noise analysis

• EMI Analysis

• Monte Carlo or worst-case circuit analysis

• Voltage ripple noise analysis

• VRM and power supply efficiency modeling

• Crosstalk analysis between power domains and sensitive signals

• PDN and impedance analysis

• Stability analysis (NISM, Bode - phase, gain, and stability margins)

• Input impedance, output impedance, startup, and transient step load response

• VRM control loop design, stability, and modeling

• Cascaded VRM and power supply analysis

• Cascaded VRM modeling

• DC drop analysis

• Voltage droop analysis

• Power Supply Rejection Ratio (PSRR) analysis

• Rogue wave analysis

• Target impedance analysis

• Supports multiphase designs – including current sharing between phases

• This model supports both DCM and CCM modes in addition to the voltage mode and current mode.

What's Included:

• Archived ADS library will be made available at checkout.

• The ADS library includes LTM4624 single-phase SSAM.

Pulling this model into an existing ADS workspace only requires a few mouse clicks.

Click here for our 4-step guide to help you add the SES Models to your ADS workspace.

Why Use a Sandler State-Space Model:

Behavioral models like SIMPLIS are available but are not designed to run fast with electromagnetic (EM) extracted S-parameter models representing the power distribution network (PDN) and cannot support end-to-end simulation.

The use of state-space average models for switched mode power supplies was started in the 1970s [1] and is an effective technique for averaging the switching behavior to get the small signal AC behavior of the switching power supply control loop in the frequency domain. Solving for the small signal behavior enables one to use that load-dependent operational point to drive the large signal switching behavior. This is what the Sandler-developed SSAM model does and makes it possible to simulate PSRR, power rail ripple, input/output impedances, switch node pulse width modulation (PWM), and regulator stability.

The SSAM is a behavioral model that simulates all noise sources going into and out of the switched mode power supply or voltage regulator module (VRM), as it is often called in the high-speed digital world.

This SSAM accurately predicts the complete VRM performance, while simple lumped models have limited use.

The SSAM, like any model, has its limits. It assumes that one is operating the regulator at a switching frequency at least six times higher than the control loop bandwidth. Keeping the VRM loop bandwidth less than 1/6th the switching frequency ensures a predictable behavior and avoids instabilities as one approaches the pulse width modulation switching frequency. At frequencies above 1/6th the switching frequency, it is the job of the PDN decoupling capacitors to deliver power.

For the highest-fidelity simulation and results, these models should be used with PCB and package effects to assess the true circuit performance.

References:

[1] S. Cuk and R. Middlebrook, “A general unified approach to modeling switching DC-to-DC converters in discontinuous conduction mode,” Power Electronics Specialists Conference, IEEE, 1977.