POWERELECTRONICS
Low current consumption It has an ultra-low current consumption of 0.3µA (at no load). There are a few product versions available with options for the CE pin and the automatic discharge function. The CE pin disables the LDO for the B and D- versions. As for the E-version, it has the possibility to disable the battery monitor circuit when not in use. It saves another 0.1µA whilst the LDO remains in operation, resulting in a current consumption of only 0.2µA.
discharged during operation. The purpose of the RP605 is to provide stable power to an MCU, Bluetooth transmitter and other peripherals. The RP605 is particularly well suited when a
supply voltage is required somewhere in between the voltage level of a fully charged and fully discharged battery. At a certain moment the DC/DC Converter switches over fromBuck to Boostmode automatically in order tomaintain the output voltage setting. The RP605 is designed for applications that aremainly in sleepmode and wake-up periodically to performameasurement, transmit data and then return to sleep mode again. For this type of application, the current consumption in sleepmode should be as low as possible. The RP605 has an impressive low quiescent current and consumes only 300nA (DC-DC Converter part). The additional batterymonitor circuit is
one of the key features of the RP605, a conventional way tomeasure the remaining storage charge is using an external resistor divider + MOSFET connected to an A/D Converter. However, the input impedance of this solution is typically low resulting in a considerable current flow to ground, draining the battery and limiting the lifetime of the application. The RP605 provides a simple solution with a built-in resistor divider and voltage follower as a buffer. As an advantage, this circuit has amuch
lower current flow to ground and the output is compatible with the input impedance of the A/D converter. The additional quiescent current of this circuit is only 100nA and has an individual chip enable pin (CE2). All essential components for this circuit are integrated into the chip, reducing valuable circuit board space and cost. In this way, it is possible tomake a simple fuel gauge for example. (Another RP604 is similar to RP605 but without a batterymonitor). The RP605 is able to provide up to 300mA
in Buckmode whilst in Boostmode the output current is less and related to the input voltage level. Multiple protection circuits are integrated,
including an Under-Voltage Lock-Out circuit which disables the DC/DC Converter in case the input voltage drops below aminimum threshold. A soft-start circuit controls the output voltage to ramp-up smoothly and
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prevents any output overshoot and undershoot during the start-up period. The Lx current limit circuit prevents the peak current through the inductor to exceed a specificmaximumcurrent threshold. An output overvoltage protection which turns off both the P-channel and N-channel MOSFETs and thermal protection, shutting down the IC in case the junction temperature increases above 140ºC.
Lowpower LDO The RP124 is a 100mA LDO regulator with a unique integrated battery voltagemonitor tomeasure the remaining charge left in the battery. It provides a simple solution with a built-in resistor divider (1/3 or 1/4 x Vin) and voltage follower as a buffer, further operation of this circuit is similar to the RP605. (Another RP118 is similar to RP124 but a without batterymonitor).
Three operating modes The RP124 is a special LDO with three operating modes: 1. Low power consumption mode, saving battery power at low output current
2. Fast transient response mode, improving dynamic performance at high output current
3. Off mode by CE pin, reducing current consumption to a minimum
The device switches automatically between the low power consumption and the fast transient response mode, based on the output current demand of the application. The performance of the LDO is improved in fast transient response mode. In particular, the ripple rejection as well as the response speed to line and load transients demonstrate better results compared to a conventional LDO with low current consumption. The RP124 can be added into the circuit to power specific peripherals with different supply voltage or requiring low noise features, such as a sensor device.
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