Teclast X21, Service Manual

Page: 56 / 76

Pin function is shown as the following figure
：
Pin Contiguous signal name Function description
1 SW Voltage output end
2 GND Grounding
3 FB Output feedback
4 EN Enable end
3.5.7 TPS79301
The TPS793xx family of low-dropout (LDO) low-power linear voltage regulators features high power
supply rejection ratio (PSRR), ultralow noise, fast start-up, and excellent line and load transient responses in
NanoStar wafer chip scale and SOT23 packages. NanoStar packaging gives an ultrasmall footprint as well as
an ultralow profile and package weight, making it ideal for portable applications such as handsets and PDAs.
Each device in the family is stable,with a small 2..2-µF ceramic capacitor on the output. The TPS793xx family
uses an advanced, proprietary BiCMOS fabrication process to yield extremely low dropout voltages (e.g., 112
mV at 200mA, TPS79330). Each device achieves fast start-up times (approximately 50µs with a 0.001-µF
bypass capacitor) while consuming very low quiescent current (170 µA typical). Moreover, when the device is
placed in standby mode, the supply current is reduced to less than 1 µA.
Pin function is shown as the following figure
：
Pin Contiguous signal name Function description
1 VIN Voltage input
2 GND Grounding
3 EN IC enable pin
4 BYPASS Internal resistor and external compose filtering circuit
5 FB Feedback
6 VOUT Voltage output
3.5.8 Function introduction to TPS62200
The TPS6220x devices are a family of high-efficiency synchronous step-down converters ideally suited
for portable systems powered by 1-cell Li-Ion or 3-cell NiMH/NiCd batteries. The devices are also suitable to
operate from a standard 3.3-V or 5-V voltage rail. With an output voltage range of 6.0 V down to 0.7 V and up
to 300 mA output current, the devices are ideal to power low voltage DSPs and processors used in PDAs,
pocket PCs, and smart phones. Under nominal load current, the devices operate with a fixed switching
- 51 -