EXHIBIT 4 

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SEPTEMBER 10, 2021

Travis Jensen

Orrick, Herrington & Sutcliffe LLP

1000 Marsh Road 

Menlo Park, CA 94025-1015

Telephone: (650) 614-7458

Facsimile: (512) 263-2166

tjensen@orrick.com

Re: Caddo Systems, Inc. et al. v. Microchip Technology Incorporated, C.A. No. 6:20-

cv-00245-ADA (W.D. Tex.)

Travis,

We write in response to Microchip’s August 13, 2021 letter (“Letter”) regarding 

Caddo Systems Inc.’s and 511 Technologies Inc.’s (“Caddo”) June 11, 2021 Final 

Infringement Contentions (“FICs”). As an initial matter, Caddo is disappointed with 

Microchip’s Letter, as it appears to either wholly ignore or intentionally disregard the 

responses in Caddo’s August 5, 2021, letter (“Reply Letter”) and the parties’ discussion 

during the August 24, 2021, meet and confer. Nevertheless, each of your concerns is readdressed below. 

I. Caddo Will Withdraw Its Allegations Pertaining To The Microchip 

Direct Website But Will Continue to Pursue Damages In Connection 

With The Microchip Direct Website

For reasons already discussed in our August 5, 2021, letter, Caddo will agree to 

withdraw its allegations against the Microchip Direct Website but will continue to pursue 

damages associated with the Microchip Direct Website, including sales (past, present, or 

future) that are diverted from www.microchip.com to the Microchip Direct Website 

through the use of the Accused Instrumentalities.

a. Microchip Fails to Identify Any Alleged “Prejudice” It Has 

Suffered Through Caddo’s FICs

As explained in Caddo’s Reply Letter, Caddo was prejudiced by Microchip’s lack 

of notice that the www.microchip.com website was redesigned, not the other way around. 

(Reply Letter at 2-3.) 

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First, Microchip maintains that because the www.microchip.com website was 

redesigned, it operates differently than the previously accused www.microchip.com

website. Not so. As shown in Caddo’s FICs, while the design of the accused 

instrumentalities may look different, their function remains largely similar (and identical 

in some instances). 

Microchip argues that it was prejudiced by Caddo’s FICs through “(1) Markman 

proceedings; and (2) invalidity contentions.” (Letter at 3.) As stated in our Reply Letter, 

these arguments do not hold water. 

First, Microchip has only itself to blame for any resulting prejudice. Having 

known that it would redesign the www.microchip.com website months before the parties 

started the claim construction briefing process (to be discussed further below), Microchip 

failed to disclose its knowledge and the extent of the design to Caddo. Indeed, the 

Court’s Order Governing Proceedings expressly required Microchip to produce 

“technical documents, including software where applicable, sufficient to show the 

operation of the accused product(s).” Despite this mandate, Microchip failed to produce 

any technical documents in connection with the redesigned website. Microchip cannot 

now play the “blame game” when it made the conscious decision to conceal such 

documents from Caddo. 

Also, the Markman proceedings in this matter began on January 21, 2021 (Dkt. 

22) and were completed on March 3, 2021 (Dkt. 26). As Microchip has stated in its 

August 25, 2021, Responses and Objections to Caddo’s First Set of Interrogatories 

(“ROG Responses”), Microchip completed its redesign of the Original Website by

“September 26, 2020” or “late 2020.” (ROG Responses at 9-10, 25.) Thus, all Markman 

proceedings were concluded months after Microchip had redesigned its website. Most 

importantly, Microchip knew that it would redesign its website as well as the scope of the 

redesign months before the hearing. Despite this knowledge, Microchip decided against 

construing terms that would have an adverse impact on its non-infringement theories.

Indeed, Microchip could easily have proposed terms covering its redesigned website and 

constructions that would support arguments now raised in Microchip’s Letter—

information that only Microchip was aware of; yet Microchip chose not to construe such 

terms even before the parties began the claim construction briefing process. That 

Microchip now seeks a second bite at the apple by claiming it suffered alleged 

“prejudice” falls flat.

Similarly, Microchip’s June 11, 2021, final invalidity contentions were completed 

months after Microchip redesigned its the Microchip Direct website. Caddo has not 

raised any new infringement theories with respect to the version of the Accused 

Instrumentalities alleged in the Complaint. Furthermore, Microchip still fails to explain 

what “new theories” have been introduced that are allegedly prejudicial. (Letter at 4.) 

As such, Caddo’s FICs have caused no prejudice to Microchip.

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II. Caddo’s Infringement Theories Are Adequately Disclosed

As discussed below, Caddo adequately disclosed its infringement theories.

a. “graphical user menu system” (Final Infringement Contentions, Ex. A 

(’411 Patent))

Caddo disagrees that its Reply Letter did not resolve any alleged deficiencies. 

The Reply Letter specifically points to examples of the “graphical user menu system”

identified in Caddo’s FICs. (Reply Letter at 3-5.) You have not even addressed the 

substance discussed in our Reply Letter. Nor have you explained why the exemplary 

elements pointed to in the Reply Letter do not sufficiently put Microchip on notice as to 

its infringement theories. 

In that regard, we confirm that we are relying on evidence identified in Caddo’s 

PICs, and examples discussed on pages 3-5 of our Reply Letter to demonstrate 

Microchip’s willful infringement. 

b. “rolling over a given active link . . . triggers the display of menu items 

on the hierarchical level associated with said given active link . . .”

(FICs, Ex. C (’517 Patent))

While Caddo disagrees with Microchip’s characterizations of Caddo’s FICs for 

this limitation, given Microchip’s representations in its Letter Caddo will also consider 

this issue resolved. 

c. “pre-selecting a given active link triggers the display of sibling menu

items . . .” (FICs, Ex. A (’411 Patent))

Microchip’s contention that Caddo has somehow disclosed “new infringement 

theories” for the term “pre-selecting” is a thinly-veiled attempt for Microchip to get a 

second bite of the claim construction apple.

As stated above, Microchip was aware of its redesigned website when Microchip 

proposed its original claim construction positions. See Section I(a). That Microchip is 

now contending that “[w]hatever else ‘pre-selecting’ a link may mean, it does not mean 

actually selecting the link by clicking on it to load a new webpage” is a blatant attempt at 

importing new meaning into a new term. Such gamesmanship has been rejected by the 

Court before. See Gree, Inc. v. Supercell Oy, C.A. No. 2:19-cv-00070-JRG-RSP, 2020 

U.S. Dist. LEXIS 165478 at *2, 6-7, 14-15 (E.D. Tex. Jul. 27, 2020) (rejecting 

defendant’s motion for summary judgment of invalidity based on an “improper claim 

construction argument[s]” advanced post-Markman).

Regardless, as stated in our Reply letter, the Court has already construed a phrase 

that contains this very term as “plain and ordinary.” (Dkt. 34 at 2.) That Microchip does 

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not agree with the Court’s construction is not ground for “sanctions and fees.” Should 

Microchip pursue such a motion in bad faith, Caddo hereby gives notice that it will seek 

its attorney fees and costs in defending against such a frivolous motion. 

Additionally, Microchip’s demand that Caddo “withdraw its allegations against 

the redesigned website” is baseless. As detailed above, Microchip redesigned its website 

in the middle of litigation, then failed to diligently inform Caddo of this fact until months 

later (and months after initial infringement contentions were due). That Caddo has 

provided in its FICs infringement theories covering Microchip’s belatedly disclosed, 

newly infringing products cannot reasonably serve as the basis for Microchip’s demand.

Finally, Microchip attempts to create confusion by arguing, for the first time, that 

Caddo’s Reply Letter demonstrates only “where the display” of sibling menu items 

occurs for this limitation, but does not identify “what must be displayed (i.e. sibling menu 

items).” (Letter at 7.) This is demonstratively false. Caddo identifies both the what and 

the where in its Reply letter and FICs. (e.g., the sibling menu items (i.e. the “what”) of 

“Overview,” “Get Started,” “Functional Safety,” “Evaluation Boards,” “System 

Features,” and “Parametric Chart” to the AVR DA product family). (Reply Letter at 7-8; 

FICs, Ex. A at 27-29.) As stated in the Reply Letter and as shown below, these sibling 

menu items are displayed “on the level associated with said given active link” (i.e. the 

“where”): 

(FICs, Ex. A, at 28.) 

Nevertheless, as a good faith attempt to resolve and reduce the number of disputes

in this matter, Caddo agrees to withdraw its infringement allegations for the newly 

Redesigned Website for claim 1 (and claims dependent thereon) of the ’411 patent. 

Caddo maintains its infringement allegations for claim 1 of the ’411 patent for the 

Original Website.

III. Caddo’s Doctrine of Equivalents (“DoE”) Allegations Are Adequate

Caddo’s DoE allegations in its FICs are more than adequate, and Caddo has 

already provided clarifications for any confusion in its Reply Letter. Microchip’s 

continued objections to Caddo’s FICs represent a basic misunderstanding of Caddo’s 

FICs and Reply Letter at best, and an intentional misreading at worst. 

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As one example, Microchip cites to Sycamore IP Holdings LLC v. AT&T Corp.

for the proposition that Caddo’s DoE infringement contentions do not meet the “more 

fulsome disclosure requirement” in this district. (Letter at 7, citing Sycamore IP 

Holdings LLC v. AT&T Corp. No. 2:16-CV-588-WCB, 2017 U.S. Dist. LEXIS 167297 at 

*13 (E.D. Tex. Oct. 10, 2017).) But as explained in Caddo’s Reply Letter, Caddo’s DoE 

contentions are distinguished from the insufficient DoE allegations in Sycamore IP. In 

Sycamore IP, the Court found the “boilerplate” language in plaintiff’s original 

contentions for plaintiff’s doctrine of equivalents infringement allegations insufficient, as 

they only provided that “[a]t present, [plaintiff] lacks knowledge . . . as to whether 

[plaintiff] will be contending that any limitations . . . are satisfied” under the doctrine of 

equivalents.” Sycamore IP at *6-7. 

Here, as explained in Caddo’s Reply Letter, Caddo has cited to and named active 

link and sibling menu items as being met under the DoE and performing substantially the 

same function in substantially the same way to obtain the same result:

[T]he limitation is met under the doctrine of equivalents by the ’411 

Accused Instrumentalities because they perform substantially the same 

function (displaying the menu items such as “Products Categories,” 

“Developments,” “Software Solutions,” “Application Design Centers,” 

and “Product Selections”) in substantially the same way (e.g. displaying 

the menu items on the level associated with the link “Microcontrollers and 

Microprocessors” to produce substantially the same result (e.g., displaying 

the menu items without disturbing the displayed Active Path (e.g. 

“Products / Microcontrollers and Microprocessors”)

(FICs, Ex. A at 29-30.)

Caddo’s FICs provide citations and screenshots to each of the above-described

limitations throughout the FICs. (See FICs, Ex. A at 19-20, 24-30.) These pages have 

“to do” with Caddo’s DoE allegations because they provide the citations and screenshots 

of the portions of Microchip’s websites that Caddo alleges infringe under the DoE. Thus, 

Microchip’s contention that “Plaintiffs do not provide any citations to particular 

webpages for their doctrine of equivalents allegations” is “plainly false” is, itself, plainly 

false. (Letter at 7.)

a. “sibling menu items” limitations

Once again, Microchip’s assertions for the “sibling menu items” limitations 

reflect a basic misunderstanding at best, or intentionally misreading at worst, of Caddo’s 

FICs. 

First and foremost, that Caddo is further clarifying its FICs does not “confirm[] 

that the theory was not adequately disclosed in the first instance.” (Letter at 8.) This 

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demonstrates Caddo’s efforts to resolve these disputes without Court interference. That 

Microchip would fault Caddo for providing these clarifications, at Microchip’s request, 

shows that Microchip is only interested in a “blame game” but otherwise lacks good faith 

in resolving any of the disputes discussed herein.

Microchip also misstates Caddo’s letter, arguing “Caddo is only asserting DOE 

for the ‘display’ portion of the claim element.” (Letter at 8.) Caddo offers this DoE 

theory “for the purpose of demonstrating that this limitation is met regardless of which 

menu items on which respective active link are displayed.” (Reply Letter at 9.) Caddo 

already walked through an example of how Microchip “still infringe[s] under Caddo’s 

DoE theory because the Accused Instrumentalities still achieve the ‘display’ of ‘sibling 

menu items on the level associated with said given active link without disturbing the 

displayed Active Path.’” (Reply Letter at 9, citing FICs, Ex. A at 20.) This citation and 

screenshot (replicated below) demonstrates the DoE theory articulated on pages 29-30 of 

Ex. A to Caddo’s FICs:

See FICs, Ex. A at 20. 

Finally, the headings and menu items “Product Categories,” “Developments,” 

“Software Solutions,” “Application Design Centers,” and “Product Selections” do appear 

“in the screenshots and figures of Microchip’s website” (see above). Microchip’s 

contention to the contrary is plainly false, and demonstrates a lack of understanding for 

both Caddo’s FICs and Caddo’s Reply Letter. (Letter at 8-9.)

b. “one or more active links allow the display of one or more items on 

the given level of the information structure when a pointer is rolled 

over one of the active links” (’880 and ’127 patents)

Again, Microchip’s assertions for the “sibling menu items” limitations reflect a 

basic misunderstanding at best, or intentionally misreading at worst, of Caddo’s FICs and 

the clarifications in the Reply Letter. 

Microchip argues Caddo “fails to explain how the ‘when a pointer is rolled over 

one of the active links’ [limitation] is satisfied under the doctrine of equivalents.” (Letter 

at 9.) Microchip also argues, for the first time, that this same deficiency extends to the 

“roll[ed/ing] over” limitation in the ’301 patent, ’517 patent, and ’836 patent. (Letter at 

9.) 

For reasons already stated in our Reply Letter, Caddo disagrees with Microchip’s 

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characterizations and arguments. Nevertheless, in a good faith attempt to resolve and 

reduce the number of disputes in this matter, Caddo agrees to withdraw its DoE 

infringement allegations for the “roll[ed/ing] over” limitation for the ’301 patent (claim 

3), ’517 patent (claims 1 and 3), ’836 patent (claim 3), ’880 patent (claims 3 and 12) and 

’127 patent (claims 3 and 16). Caddo maintains its infringement allegations for the 

Original Website.

For at least these reasons, we disagree that Microchip is prejudiced in any way by 

Caddo’s FICs as to Caddo’s DoE theories.

* * *

If Microchip prefers to meet and confer again on any of the issues identified 

herein, Caddo is available. 

Sincerely,

/s/ Alex Chan

 Alex Chan

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