<PAGE>   1
                                                                  EXHIBIT 10.39


                              TRITEAL CORPORATION
                                    NON-PLAN
                      NONSTATUTORY STOCK OPTION AGREEMENT
                                 (FACING PAGE)

         FOR GOOD AND VALUABLE CONSIDERATION, TriTeal Corporation, a Delaware
corporation, hereby irrevocably grants to the Optionee named below a
nonstatutory stock option (the "Option") to purchase any part or all of the
specified number of shares of its Common Stock upon the terms and subject to
the conditions set forth in this Option Agreement, at the specified purchase
price per share without commission or other charge.  The Option is subject to
the Terms and Conditions Relating to Nonstatutory Stock Option (the "Terms and
Conditions") attached hereto.  The provisions of the Terms and Conditions are
hereby incorporated herein by reference and made a part of this Option
Agreement.



<TABLE>
<CAPTION>
Name of Optionee:                                                 David Y. Chen
<S>                                                               <C>
Social Security Number:
                                                                  -------------

Number of Shares covered by
Option (the "Option Shares"):                                     160,000

Purchase Price Per Option Share:                                  $10.25

Minimum Number of Option Shares Per
Partial Exercise (unless Optionee exercises
all of the Option then exercisable):
                                                                  -------------
</TABLE>

The Option shall become exercisable as follows:

          1/2 of the total number of shares granted hereunder shall vest on
         July 22, 1998, and thereafter 1/24th of the remaining number of shares
         shall vest on the 22nd of each month, such that the options shall be
         100% vested on July 22, 2000.  Notwithstanding the foregoing, in the
         event that (1) the employment of the Optionee is terminated by the
         Company prior to July 22, 1998 other than for Cause (as that term is
         defined in the Terms and Conditions), or (2) the Optionee terminates
         his employment with the Company prior to July 22, 1998 for Good Reason
         (as that term is defined in the Terms and Conditions), then 1/2 of the
         total number of shares granted hereunder shall be 100% vested
         immediately following such event.  Once subject to purchase, the
         Option Shares shall remain subject to purchase until July 21, 2007
         (the "Expiration Date") unless the Option is earlier terminated in
         accordance with the Terms and Conditions.

Date of this Option Agreement:  July 22, 1997

TRITEAL CORPORATION                              ______________________________
                                                 Optionee's Signature



By:____________________________                  Residence Address:
   Name:_______________________                  ______________________________
   Title:______________________                  ______________________________











<PAGE>   2
                        TERMS AND CONDITIONS RELATING TO
                                    NON-PLAN
                           NONSTATUTORY STOCK OPTION
                            GRANTED TO DAVID Y. CHEN


                                 July 22, 1997



         The following Terms and Conditions Relating to Non-Plan Nonstatutory
Stock Option (the "Terms and Conditions") apply to the Option to which it is
attached.  Whenever capitalized terms are used in these Terms and Conditions,
they shall have the meaning specified in the TriTeal Corporation Nonstatutory
Stock Option Agreement Facing Page (the "Facing Page") into which these Terms
and Conditions are incorporated by reference, or below, unless the context
clearly indicates to the contrary.  As used herein, the "Option Agreement"
shall mean the Nonstatutory Stock Option Agreement Facing Page and these Terms
and Conditions as incorporated therein.  The masculine pronoun shall include
the feminine and neuter, and the singular the plural, where the context so
indicates.

         1.      TERM OF OPTION.  Subject to the maximum time limitations
described herein, the term of the Option shall be the period commencing on the
date of the Option Agreement and ending on the Expiration Date (as defined in
the Facing Page), unless terminated earlier as provided herein or in the Plan.

         2.      EXERCISE OF OPTION.

                 (a)      The Facing Page shall set forth the rate at which the
Option Shares shall become subject to purchase by Optionee.

                 (b)      "Cause," as that term is used in the Facing Page,
shall mean misconduct, including:  (i) conviction of any felony or any crime
involving moral turpitude or dishonesty; (ii) participation in a fraud or act of
dishonesty against the Company; (iii) willful breach of the Company's policies;
(iv) intentional damage to the Company's property; (v) material breach of
Optionee's employment agreement or Optionee's Proprietary Information and
Inventions Agreement; or (vi) conduct by Optionee which in the good faith and
reasonable determination of the Board demonstrates unacceptable job performance
or gross unfitness to serve.  Physical or mental disability shall not constitute
Cause.  "Good Reason," as that term is used in the Facing Page, shall mean (i)
substantial reduction of Optionee's rate of compensation as in effect as the
date hereof (except to the extent that substantially all other officers of the
Company are similarly affected); (ii) failure to provide a package of welfare
benefit plans which, taken as a whole, provide substantially similar benefits to
those in which the Optionee is entitled to participate as of the date hereof
(except that employee contributions may be raised to the extent of any cost
increases imposed by third parties) or any action by the Company which would
adversely affect Optionee's participation or substantially reduce Optionee's
benefits under any of such plans (except to the extent that substantially all
other officers of the Company are similarly affected); (iii) change in
Optionee's employment responsibilities, authority, title or office resulting in
diminution of position, excluding for this purpose an isolated, insubstantial
and inadvertent action not taken in bad faith which is remedied by the Company
promptly after notice thereof is given by Optionee; or (iv) requirement that
Optionee relocate his current residence, unless Optionee accepts the request of
the Company to make such relocation.





                                       1.
<PAGE>   3


                 (c)      Optionee shall exercise the Option to the extent
exercisable, in whole or in part, by sending written notice to the Company in
the form attached hereto as Exhibit A of his intention to purchase Option
Shares hereunder.  Optionee shall not exercise the Option at any one time with
respect to less than the minimum number of Option Shares as is set forth on the
Facing Page.

                 (d)      Payment of the exercise price per share is due in
full upon exercise of all or any part of each installment which has accrued to
the Optionee.  The Optionee may elect, to the extent permitted by applicable
statutes and regulations, to make payment of the exercise price under one of
the following alternatives.

                          (i)     Payment of the exercise price per Option
Share in cash (including check) at the time of exercise;

                          (ii)    Payment pursuant to a program developed in
compliance with regulations promulgated by the Federal Reserve Board which,
prior to the issuance of the Option Shares, results in either the receipt of
cash (or check) by the Company or the receipt of irrevocable instructions to a
qualified broker that sufficient Option Shares to pay the aggregate exercise
price be sold immediately and that the exercise price be delivered to the
Company from the sales proceeds; or

                          (iii)   Payment by a combination of the above methods
of payment.

                 (e)      Optionee agrees to complete and execute any
additional documents which the Company reasonably requests that Optionee
complete in order to comply with applicable federal, state and local securities
laws, rules and regulations.

                 (f)      Subject to the Company's compliance with all
applicable laws, rules and regulations relating to the issuance of such Option
Shares and Optionee's compliance with all the terms and conditions of the
Option Agreement and these Terms and Conditions, the Company shall promptly
deliver the Option Shares to the Optionee.

                 (g)      Except as otherwise provided herein, the Option may
be exercised during the lifetime of the Optionee only by the Optionee.

         3.      OPTION NOT TRANSFERABLE.  The Option granted hereunder shall
not be transferable in any manner other than upon the death of Optionee.  More
particularly (but without limiting the foregoing), the Option may not be
assigned, transferred (except as expressly provided herein), pledged or
hypothecated in any way, shall not be assignable by operation of law and shall
not be subject to execution, attachment or similar process.  Any attempted
assignment, transfer, pledge, hypothecation or other disposition of the Option
contrary to the provisions hereof, or the levy of any execution, attachment or
similar process upon the Option, shall be null and void and without effect.

         4.      TERMINATION OF OPTION.

                 (a)      To the extent not previously exercised, the Option
shall terminate on the Expiration Date; provided, however, that except as
otherwise provided in this Section 5 the Option may not be exercised more than
thirty (30) days after the termination of Optionee's continuous status as an
employee, director or consultant for any reason (other than upon Optionee's
death or








                                       2.



<PAGE>   4

disability). Within such thirty (30) day period, Optionee may exercise the
Option only to the extent the same was exercisable on the date of such
termination of Optionee's continuous status as an employee, director or
consultant, and said right to exercise shall terminate at the end of such
period.

                 (b)      In the event of a termination of Optionee's
continuous status as an employee, director or consultant as a result of
Optionee's disability, the Option shall be exercisable for a period of twelve
(12) months from the date of such termination of Optionee's Continuous status
as an employee, director or consultant, but in no event later than the
Expiration Date and only to the extent that the Option was exercisable on the
date of such termination.

                 (c)      In the event of a termination of Optionee's
continuous status as an employee, director or consultant as a result of
Optionee's death, the Option shall be exercisable by the Optionee's estate (or
by the person who acquires the right to exercise the Option by will or by the
laws descent and distribution or by designation) for a period of twelve (12)
months from the date of such termination, but in no event later than the
Expiration Date and only to the extent that the Optionee was entitled to
exercise the Option on the date of death.

                 (d)      Notwithstanding anything herein to the contrary, no
portion of any Option which is not exercisable by the Optionee upon a
termination of Optionee's continuous status as an employee, director or
consultant shall thereafter become exercisable, regardless of the reason for
such termination.

         5.      NO RIGHT TO CONTINUED EMPLOYMENT.  The Option does not confer
upon Optionee any right to continue in his or her capacity as an employee,
consultant or director of the Company, nor does it limit in any way the right
of the Company to terminate Optionee's service relationship with the Company at
any time, with or without cause.

         6.      NOTICE OF TAX ELECTION.  If Optionee makes any tax election
relating to the treatment of the Option Shares under the Internal Revenue Code
of 1986, as amended, Optionee shall promptly notify the Company of such
election.

         7.      ACKNOWLEDGMENTS OF OPTIONEE.  Optionee acknowledges and
agrees that Optionee and his or her transferees shall have no rights as a
shareholder with respect to any Option Shares until the date of the issuance of
a stock certificate (or such other means of issuance of the Option Shares as
provided by the Company evidencing such Option Shares.  No adjustment shall be
made for dividends (ordinary or extraordinary, whether in cash, securities or
other property) or distributions or other rights for which the record date is
prior to the date such stock certificate is issued.

         8.      WITHHOLDING TAXES.  Whenever Option Shares are to be issued
under the Option Agreement, the Company shall have the right to require Optionee
to remit to the Company an amount sufficient to satisfy federal, state and local
withholding tax requirements prior to issuance and/or delivery of any
certificate or certificates for such Option Shares.






                                       3.
<PAGE>   5



         9.      MISCELLANEOUS.

                 (a)      The Option Agreement shall bind and inure to the
benefit of the parties' heirs, legal representatives, successors and permitted
assigns.

                 (b)      The Option shall be administered by the Compensation
Committee of the Company's Board of Directors (the "Committee"), which shall
have the power to construe and interpret the Option and otherwise to exercise
such authority with respect to the Option as it possesses as to options granted
under the TriTeal Corporation 1995 Stock Option Plan (the "Plan").  To the
extent practical, the option shall be administered and interpreted in a manner
consistent with nonstatutory options granted under the Plan.

                 (c)      Subject to Section 9(b) above, the Option Agreement
and these Terms and Conditions constitute the entire agreement between the
parties pertaining to the subject matter contained herein and they supersede
all prior and contemporaneous agreements, representations and understandings of
the parties.  No supplement, modification or amendment of the Option Agreement
shall be binding unless executed in writing by all of the parties.  No waiver
of any of the provisions of the Option Agreement shall be deemed or shall
constitute a waiver of any other provisions, whether or not similar, nor shall
any waiver constitute a continuing waiver.  No waiver shall be binding unless
executed in writing by the party making the waiver.

                 (d)      Should any portion of the Option Agreement or these
Terms and Conditions be declared invalid and unenforceable, then such portion
shall be deemed to be severable from the Option Agreement and shall not affect
the remainder hereof.

                 (e)      All notices to be sent hereunder shall be delivered
in person or sent by United States Mail, certified and postage prepaid, to
Optionee at the address set forth on the Facing Page of the Option Agreement or
to the Company at its principal place of business, Attention:  Chief Financial
Officer.  Any change in the address to which notices shall be sent under the
Option Agreement to the Optionee shall be made by the Optionee upon ten (10)
days' written notice to the Company.

                 (f)      The prevailing party in any court action brought to
interpret or enforce any provision of the Option Agreement shall be entitled to
recover, as an element of the costs of suit, and not as damages, an award of
reasonable attorneys' fees, to be fixed by the court.  Such award may be made
as part of a judgment by default or as part of a judgment after trial or after
appeal.





                                       4.
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                                   EXHIBIT A



                NOTICE OF EXERCISE OF NONSTATUTORY STOCK OPTION

                               (NON-PLAN OPTION)



To:      TriTeal Corporation
         2011 Palomar Airport Road
         Carlsbad, CA  92009-1432



         I, a resident of the State of _____________________, hereby exercise
my nonstatutory stock option granted by TRITEAL CORPORATION, a Delaware
corporation (the "Company"), pursuant to a Nonstatutory Stock Option Agreement
dated __________, 199__, subject to all the terms and provisions thereof and
notify the Company of my desire to purchase _____ shares of Common Stock of the
Company at the exercise price of _______________ Dollars ($_______) per share
pursuant to said option.


         I agree to complete and execute any additional documents which the
Company may request that I complete in order to comply with applicable federal,
state and local securities laws, rules and regulations.





Dated:  _______________________





_______________________________                 _______________________________
Social Security or                              [Name]
Taxpayer I.D. Number



                                                Address:
                                                _______________________________
                                                _______________________________
                                                _______________________________