XR79106

22V, 6A Synchronous Step-Down COT Power Module
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Overview

Information
# of Outputs 1
IOUT/Ch (A) 6
VIN MIN (V) 3
VIN MAX (V) 22
IQ (µA) 700
VOUT MIN (V) 0.6
VOUT MAX (V) 5.5
Frequency (kHz) 600-800
Efficiency (%) 95
X-Y Dimension (mm) 8x8
Z Dimension (mm) 4
Package QFN
Features UVLO, OTP, Soft Start/Tracking, Adjustable hiccup current limit, Short Circuit Protection, PGOOD
Junction Temp Range (°C) -40 to 125
Show more

The XR79106 is part of a family of 22V synchronous step-down power modules combining the controller, drivers, Inductor, passive components and MOSFETs in a single package for point-of-load supplies. This module requires very few external components leading to ease of design and fast time-to-market. The XR79106 has load current rating of 6A. A wide 4.5V to 22V input voltage range allows for single supply operation from industry standard 5V, 12V and 19.6V rails.

With a proprietary emulated current mode Constant On-Time (COT) control scheme, the XR79106 provides extremely fast line and load transient response using ceramic output capacitors. It requires no loop compensation, simplifying circuit implementation and reducing overall component count. The control loop also provides 0.2% line and load regulation and maintains constant operating frequency.

A selectable power saving mode, allows the user to operate in Discontinuous Current Mode (DCM) at light current loads thereby significantly increasing the converter efficiency.

A host of protection features, including overcurrent, over temperature, short-circuit and UVLO, helps achieve safe operation under abnormal operating conditions.

The XR79106 is available in a RoHS-compliant, green/halogen-free space-saving 8mm x 8mm x 4mm QFN package.

  • 6A step-down power module
    • Offers power system ease of design
    • 4.5V to 22V wide single input voltage
    • 3.0V to 22V input range with external bias
    • ≥0.6V adjustable output voltage
  • Controller, drivers, inductor, passive components and MOSFETs integrated in one package
  • Proprietary constant on-time control
    • No loop compensation required
    • Stable with ceramic output capacitors
    • Programmable 100ns to 1μs on-time
    • Constant 600kHz to 800kHz frequency
    • Selectable CCM or CCM/DCM operation
  • Precision enable and power good flag
  • Programmable soft-start
  • 8mm x 8mm x 4mm QFN package
  • 22V, 3A power module (XR79103)
  • 22V, 10A power module (XR79110)
  • 40V, 3A power module (XR79203)
  • 40V, 6A power module (XR79206)

  • Drones and remote vehicles
  • FPGA/DSP/processor supplies
  • Industrial control and automation
  • RAID storage systems
  • Telecommunications and infrastructure equipment
  • Distributed power architecture

Documentation & Design Tools

Type Title Version Date File Size
Data Sheets XR79106 22V, 6A Synchronous Step-Down COT Power Module 3A June 2021 1.9 MB
Data Sheets XR79106 Data Sheet Rev 2B 2B April 2020 1.9 MB
Application Notes AN-230, Layout Guidelines for XR791xx Family R00 March 2020 2.4 MB
Application Notes ANP-47, Design for EMI 1.0 March 2016 1.2 MB
User Guides & Manuals XR79106 Evaluation Board Manual Rev. 1A May 2016 1.4 MB
Product Flyers Power Modules April 2019 1.1 MB
Product Brochures Power Management Brochure October 2020 2.4 MB
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Quality & RoHS

Part Number RoHS | Exempt RoHS Halogen Free REACH TSCA MSL Rating / Peak Reflow Package
XR79106EL-F N Y Y Y Y L3 / 260ᵒC QFN49 8x8

Click on the links above to download the Certificate of Non-Use of Hazardous Substances.

Additional Quality Documentation may be available, please Contact Support.

Parts & Purchasing

Part Number Pkg Code Min Temp Max Temp Status Buy Now
XR79106EL-F QFN49 8x8 -40 125 Active
XR79106EVB Board Active

Part Status Legend
Active - the part is released for sale, standard product.
EOL (End of Life) - the part is no longer being manufactured, there may or may not be inventory still in stock.
CF (Contact Factory) - the part is still active but customers should check with the factory for availability. Longer lead-times may apply.
PRE (Pre-introduction) - the part has not been introduced or the part number is an early version available for sample only.
OBS (Obsolete) - the part is no longer being manufactured and may not be ordered.
NRND (Not Recommended for New Designs) - the part is not recommended for new designs.

Packaging

Pkg Code Details Quantities Dimensions PDF
QFN49 8x8
  • JEDEC Reference:
  • MSL Pb-Free: L3 @ 260ᵒC
  • MSL SnPb Eutectic:
  • ThetaJA: 32.2
  • Bulk Pack Style: Tray
  • Quantity per Bulk Pack: 260
  • Quantity per Reel: n/a
  • Quantity per Tube: n/a
  • Quantity per Tray: 260
  • Reel Size (Dia. x Width x Pitch): n/a
  • Tape & Reel Unit Orientation: n/a
  • Dimensions: mm
  • Length: 8
  • Width: 8
  • Thickness: 4.1
  • Lead Pitch: 0.5

Notifications

Distribution Date Description File
10/03/2023 MaxLinear has qualified ATX Group, Suzhou (ATXSZ) assembly site for the part numbers listed above. Please note bill of material (BOM) changes in the Change Details section below. There is no change to form, fit, function and reliability of the parts.
02/07/2022 MaxLinear has qualified an alternate FET fab location to ensure continuity of supply.
03/19/2021 To improve manufacturing availability, MaxLinear will be converting the 3 products listed from GQFN to QFN package technology. Pin number designators will not be changed to avoid customers needing to change existing schematics and other documentation. There is no change to product form, fit, or function. A Technical Note is included to address nuances associated with the two package types.
03/04/2020 MaxLinear is announcing the replacement of the QFN package with a GQFN package for improved manufacturability margin at customer's SMT process. - Addendum
02/13/2020 MaxLinear is announcing the replacement of the QFN package with a GQFN package for improved manufacturability margin at customer's SMT process.

FAQs & Support

Search our list of FAQs for answers to common technical questions.
For material content, environmental, quality and reliability questions review the Quality tab or visit our Quality page.
For ordering information and general customer service visit our Contact Us page.

Submit a Technical Support Question As a New Question

The Exar controllers, regulators and power modules are powered by an internal LDO to produce the Vcc rail that their circuits need to run properly. If the input voltage that feeds the LDO is the minimum Vin as specified on the datasheet or above, the Vcc is enough to power the device and the Vin, Vcc and PVIN pins can be connected together.

If the input voltage is 5V, then the Vin and Vcc pins can be tied together and the input voltage is fed to the PVIN pin.

If input voltage is below 5V, then a separate low current 5V supply (common in many systems) is connected to the Vin and Vcc pins which are tied together to keep the device running properly. The input voltage is connected to the PVIN pin.

Voltage mode PWM

Voltage mode PWM is a simple technique that uses a single loop to control the output voltage. As shown in Figure 1, the output voltage is compared to a reference voltage with an error amplifier. The output of the error amplifier is then compared to a sawtooth and that output is used to drive the MOSFET, usually via a voltage divider.

 


Figure 1

 

As shown in Figure 2, the output voltage is modulated by turning the high-side FET on (on-time) with the pulse width and turning the low side FET off. At the end of the pulse, the high-side FET is turned off (off-time) and the low side FET is turned on until the next pulse. Vout = On-Time/Period * Vin.

 

Figure 2
 

The advantages of voltage mode PWM is that it is a very simple, common, smaller solution with good accuracy. The disadvantages are that complex frequency compensation is required (two poles) to stabilize the loop and because trailing edge control is most commonly used, there is a delay in load step response.

Current mode PWM

With voltage mode PWM, current is less known. For better control, current mode PWM senses the inductor current and it is compared to the reference voltage as shown in Figure 3.

 


Figure 3

 

Although the current has to be sensed with accuracy and introduces noise, the advantages of current mode PWM are easier loop compensation (less compensation needed with one pole), and it is easier to implement over-current protection and parallel currents to the output.

Standard Constant On-Time (COT)

As opposed to PWM, the pulse width in COT is always the same as shown in Figure 4. Instead the off-time length varies (as does the frequency) which modulates the output. As the Vout increases, the off-time of the duty cycle increases (frequency decreases) and the fixed on-time produces a lower duty cycle. This transfers less energy to the output and lowers the Vout. More simply said, as Vout increases, the duty cycle decreases. Conversely, as the Vout decreases, the off-time of the duty cycle decreases (frequency increases) and the fixed on-time produces a higher duty cycle. This transfers more energy to the output and raises the Vout.

 


Figure 4

 

The advantages of standard COT are very fast transient response, simplicity (inexpensive) and that frequency compensation is not complex as it is in PWM control. However, the feedback signal tends to have low amplitude and signal to noise ratio, making it very noise sensitive. Also, the output voltage is higher than the reference voltage and the ripple is dependent on and sensitive to the output capacitor ESR. This introduces a DC offset which is the average amount the output voltage is over the reference voltage. It is also jitter prone and the frequency changes during the load steps.

Some solutions solve the noise sensitivity by having one of two options that condition the feedback signal but introduce delays. One tradeoff provides faster transient responses; the other allows low ESR output capacitors to be used.

MaxLinear’s patented COT

MaxLinear’s patented COT architecture however conditions the reference instead as shown in Figure 5. The MaxLinear devices create their own emulated ramp that is insensitive to noise and the ESR of the capacitor. Since the output capacitor ESR does not affect it, low ESR ceramic capacitors can be used and maintain stability without decreasing speed. In addition, the Vout and reference voltage are compared and that result controls the ramp circuit. This creates a slower loop where the output voltage is averaged out and the DC offset is not introduced as in standard COT.

 


Figure 5

 

MaxLinear’s COT still has the standard COT advantages of very fast transient response, simplicity and no complex frequency compensation in addition to not having DC offset or ESR value sensitivity. MaxLinear’s COT architecture provides exceptional line and load regulation.

Find the product page of the part that you want to get an evaluation board for and click on Parts & Purchasing. Example:

 

Find the icons under Buy Now or Order Samples:

 
 

Click on the Buy Now icon and see who has stock and click on the Buy button:

 
 
 

Alternatively, you can click on the Order Samples

 
 

If the icons are missing, then contact Customer Support.

In PWM controllers, frequency is constant and tON (on-time) is set by the controller to regulate the output voltage. However in COT controllers, the tON is constant and set by the RON resistor. This also sets the frequency. RON is connected between the TON pin and GND.

If the high-side FET was ideal, the tON of the SW signal would be equal to tON of GH (high-side FET gate) signal and the relationship between RON and tON would be:

 
 

However, the high side FET has rise and fall times as well as on and off delay times, so the tON of SW is not equal to GH. This non-ideal characteristic is measured for each regulator or module where the above equation is modified. In the Applications Information of each regulator or module datasheet, an equation defining the relationship of RON and tON is given based on test data for that device. For example, in the XR79206 power module datasheet, you will find the following equation in the Programming the On-Time section of the Applications Information:

 
 
 

The correlation of this equation to the test data is also given in the datasheet. In the XR79206 example, Figure 5 in the Typical Performance Characteristics section shows very good correlation:

 
 
 In an ideal Buck Converter, tON is a function of VIN, VOUT and f expressed in following equation:
 
 

However, as no Buck Converter is ideal, test data is taken to determine a more accurate equation which is also given in the datasheet. In the XR79206 example, the following equation is given based on test data:

 
 
 

Substituting this tON equation into the above equation relating RON and tON and simplifying, we get:

 
 
 

Then RON can be easily chosen based on the targeted VIN, VOUT, frequency and efficiency. So for example in the XR79206, if VIN = 24V, VOUT = 5V, f = 500kHz and efficiency = 90%,

 
 
 
 
The next closest commercially available resistor value can be used. Several RON examples are given in the datasheets based on the above equation for your convenience. For a given RON it should be noted that tON is inversely proportional to VIN. This inverse relationship allows the frequency to remain constant as VIN changes, except for some changes due to the non-ideal nature of the power components. For example, this is illustrated in the following graph from the XR79206:
 
 
 

As IOUT increases, frequency increases slightly due to increasing power losses. As losses increase, more power must be delivered per cycle to keep VOUT constant. Because tON is constant, the period decreases and frequency increases, as can be seen in the following example from the XR79206 datasheet:

 
 
 
 
 
 

The -F suffix indicates ROHS / Green compliance:
https://www.exar.com/quality-assurance-and-reliability/lead-free-program

Visit the product page for the part you are interested in.  The part's status is listed in the Parts & Purchasing section.  You can also view Product Lifecycle and Obsolescence Information including PDNs (Product Discontinuation Notifications).
 
To visit a product page, type the part into the search window on the top of the MaxLinear website.
 
In this example, we searched for XRA1201.  Visit the product page by clicking the part number or visit the orderable parts list by clicking "Orderable Parts". 
 
 
 

 

  

The Parts & Purchasing section of the product page shows the Status of all orderable part numbers for that product.  Click Show obsolete parts, to see all EOL or OBS products.

 
 
 

 

The COT families (XRP6141, XRP6124 and XR75100 controllers, XR76xxx regulators and XR79xxx power modules) have 2 modes of operation that can be set: DCM / CCM (discontinuous conduction mode / continuous conduction mode) or FCCM (Forced CCM) mode. In FCCM mode, the converter operates at a preset frequency regardless of output current. In DCM / CCM mode the converter operates in DCM or CCM depending on the Iout magnitude. If Iout < ½ Ipp, the converter transitions to DCM mode. If Iout is higher, operation is in CCM mode.

The main advantage of DCM / CCM is that it provides significantly higher efficiency at light loads. For those applications where that doesn’t matter, FCCM can be used and has the advantage that it allows for operation at a constant frequency, regardless of load. It also results in lower Vout ripple, and will operate in an inaudible range.

Size Cout for required load step transient response, for example <3% VOUT transient for a 0 – 50% rated current. Cout also needs to be sized for steady state output voltage ripple. Use effective value of capacitors corresponding to operating conditions.

Place small signal components close to their respective pins.

Place CIN capacitors close to PVIN / PGND pins.

In general, it is set for Imax x 1.5. It would be close the maximum Iout (including ripple). If conservatively set too high, the hiccup mode may not be activated fast enough. If set too low, the ripple could cause the current to go over the threshold and set it into hiccup on a pre-mature basis.

 

The datasheets have an equation that calculates the Rlim resistor value to be used to program the Iocp. Also, a graph of Iocp vs. I lim is shown in the datasheet.

A zero-cross comparator monitors the voltage across the low-side FET when it is on. The comparator threshold is nominally set at -1mV or -2mV (see individual datasheet). If there is sufficient IOUT such that VSW is below the threshold and therefore does not trigger the zero-cross comparator, CCM operation continues.

 

As IOUT is reduced, VSW gets closer to ground. When VSW meets the threshold, the zero-cross comparator triggers. If there are 8 consecutive triggers, then DCM operation begins. The low side FET is turned off when IL x RDS equals the zero-cross threshold.

 

As there is no negative inductor current, the charge transferred to COUT is preserved. As IOUT decreases further, less charge transfer to COUT is required. Pulses grow further apart, frequency is reduced and efficiency increases.

 

DCM persists as long as there are 8 consecutive zero-crosses.

 

Note that when the DCM frequency falls below about 1kHz, the controller turns on the lower-side FET for 100ns once every 1.2ms to refresh the charge on the bootstrap capacitor. This refresh cycle generates small spikes on SW, which can be seen interlaced between DCM pulses.