General Instructions
ADM8830 charge pump regulator for color thin film transistor (TFT) liquid crystal displays (LCD). Using charge pump technology, the device can be used to generate three 3 V input supplies from a single output voltage (5.1 V ± 2%, 15.3 V, -10.2 V). These outputs are then used to provide the LCD controller (5.1 V) and gate drive power to the transistors on the panel (15.3 V and -10.2 V). Only a few require an external capacitive charge pump. A high efficiency low dropout regulator also ensures high power efficiency and provides a low ripple 5.1 V output. This LDO can be turned off, and an external LDO is used to regulate the charge pump section at the 5 V multiplied output and input driver, which generates 15.3 V and -10.2 V outputs, if required by the user. The ADM8830 uses the internal 100 kHz oscillator in scan mode, but the part must be clocked by an external clock source in blanking (low current) mode. The internal oscillator used for the charge pump clock is currently the highest in scan mode. During the blanking period, the ADM8830 switches to use an external, lower frequency clock. This allows users to maximize power efficiency at different frequencies and during blanking periods. Tolerance on the output voltage is maintained seamlessly when switching between scan mode, blanking mode or vice versa. The ADM8830 has power-saving features, including low-power shutdown and quiescent current consumption that reduces the blanking period mentioned above, during the period. The 5.1 V output dissipates the maximum power so that power efficiency is also maximized with an oscillator that enables the output of the scheme (Green Idle™). This will effectively detect the flow of load current and meander the charge pump when charging needs to be delivered to the 5 volt pump multiplier output. The ADM8830 is built with minimal power consumption in CMOS technology. Parts are available in 20-pin LFCSP and TSSOP packages.