With the rapid advancement of smart electronic devices, display screen technology has also been continuously evolving; AMOLED (Active Matrix Organic LED) displays are gradually replacing LCD's to become the mainstream choice in the market.

     AMOLED displays are thinner and lighter than LCD displays, offer faster response times, support active back-lighting, exhibit flexibility, and provide a wider color gamut. Consequently, AMOLED has become the preferred choice for high-end display applications. The OCP21351 is a power management chip specifically designed for small-size AMOLED displays; it features three output voltage rails—AVDD, OVDD, and OVSS—along with a single-line interface and programmable output voltages.

     The OCP21351 is a highly integrated AMOLED power solution, particularly suitable for wearable devices. By drawing an input power voltage ranging from 2.9 V to 4.6 V from the battery, the OCP21351 generates AVDD, OVDD, and OVSS outputs based on the target settings.

     OCP21351 operates in either symmetric or asymmetric mode, as defined by the SAS pin. Before startup, prior to the EN pin rising to a high level, the state of the SAS pin must be held steady.

     In symmetric mode, SAS is set to the Low level, and the initial output voltages of AVDD, OVDD, and OVSS are 3.3 V, 3.3 V, and-2.2 V, respectively. In asymmetric mode, SAS is set to the High level, and the initial output voltages of AVDD, OVDD, and OVSS are 2.8 V, 4.6 V, and-2.2 V, respectively.

The OCP21351 also integrates a serial data interface to provide flexibility in various configuration settings. However, in asymmetric operation, only the voltage settings of OVSS and AVDD can be adjusted. It features built-in under voltage lockout, short-circuit protection, and thermal shutdown protection.

     The OCP21351 features the WLCSP-21B package, providing an optimized PCB layout solution.

     The practical application of OCP21351 supports two operating modes—symmetric and asymmetric—selecting the appropriate mode based on specific requirements: in asymmetric mode, VINA must be connected to VIN, whereas in symmetric mode, VINA must be connected to BST. Set this configuration before using the chip.