you can also read this case.. G.R. No. 170087

Constructive dismissal is an involuntary resignation resulting in cessation of work resorted to when continued employment becomes impossible, unreasonable or unlikely; when there is a demotion in rank or a diminution in pay; or when a clear discrimination, insensibility or disdain by an employer becomes unbearable to an employee.
http://sc.judiciary.gov.ph/jurisprud...002/150092.htm

In Globe Telecom, Inc. v. Florendo-Flores, we ruled that where an employee ceases to work due to a demotion of rank or a diminution of pay, an unreasonable situation arises which creates an adverse working environment rendering it impossible for such employee to continue working for her employer. Hence, her severance from the company was not of her own making and therefore amounted to an illegal termination of employment.