Application of low voltage dropout voltage regulator chip R1114

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Application of low voltage dropout voltage regulator chip R1114 [Copy link]

With the rapid increase in demand for portable electronic devices such as mobile phones, PDAs, and MP3s, the voltage of these battery-powered products is relatively low, and there are multiple internal power supply voltages. Therefore, a step-down device that can work at low voltage and has the convenience of a three-terminal regulator is needed. At the same time, it must have a small package size, so LDO was developed and used in large quantities. This type of device not only meets the requirements of small size,

With the rapid increase in demand for a large number of portable electronic devices such as mobile phones, PDAs, and MP3s, the voltage of such battery-powered products is low, and there are multiple internal power supply voltages. Therefore, a step-down device that can work at low voltage and has the convenience of using a three-terminal regulator is needed. At the same time, it must have a small package volume, so LDO was developed and used in large quantities. This type of device not only meets the small size, small voltage difference and low voltage working characteristics, but also has low power consumption. The
R1114 series produced by Ricoh of Japan is a voltage regulation chip with high output voltage accuracy, low power consumption, low on-resistance, high ripple suppression and CMOS technology. Because this series has good linear transient characteristics and transient characteristics when loaded, it is very suitable for powering handheld communication equipment. The R1114 package adopts small-volume SOT-23-5 and SC-82AB, which is conducive to high-density installation on a board. In addition, this series has a built-in overcurrent protection circuit, can be connected to an external ceramic capacitor, and has a fast discharge function. The principle block diagram of R1114 is shown in Figure 1.
In Figure 1
, the internal resistance of the LDO Vout is set. When placing an order, you only need to tell the manufacturer the required voltage value, so the use of the entire circuit is as convenient as a three-terminal voltage regulator. When there is a DC voltage greater than Vout at the input end, a predetermined voltage will appear at the Vout end, where Vdd-Vout is the voltage difference of the LDO. When Vout is set, when Vdd drops and falls to a value, the LDO will exit the voltage regulation. At this time, Vout will also drop. Before the LDO exits the voltage regulation, there is also a Vdd-Vout, which is the minimum voltage difference of the LDO. The minimum voltage difference of the LDO is related to Iout. The larger the Iout, the larger the minimum voltage difference. The minimum voltage difference is also related to the on-resistance value of the internal power device. In the D series of the R1114 series, a MOS tube is connected between Vout and GND inside the LDO. When the CE pin is not selected, the MOS tube is turned on to allow the external capacitor connected to the Vout end to discharge quickly through the MOS tube. Its peripheral circuit is shown in Figure 2.
When using these chips, two aspects should be noted: 1. In these ICs, in order to make the chip work properly even when the load current changes, phase compensation should be used. An output capacitor with stable frequency characteristics and equivalent series resistance should be used.
2. Make the wiring of Vdd and GND pins thick enough. If their impedance is too high, the generated noise may affect the output. Connect a 1.0mF capacitor between the Vdd and GND pins, and the capacitor must be as close to the corresponding pins of the IC as possible.