PFM Control, Step-Up Synchronous DC/DC Converter
The XC9140 series are step-up synchronous DC/DC converters that support ceramic capacitors and have an internal 0.6Ω (TYP.) Nch driver transistor and an internal 0.65Ω (TYP.) Pch synchronous rectifier switch transistor. PFM control enables a low quiescent current, making these products ideal for portable devices that require high efficiency.
When the output voltage is 3.3V and the output current is 1mA, startup from an input voltage of VBAT=0.9V is possible which means that the XC9140 can be used in applications that start from a single alkaline or nickel-metal hydride battery. The output voltage can be set from 1.8V to 5.0V (±2.0%) in steps of 0.1V.
The XC9140 features a load disconnect function to break continuity between the input and output at shutdown (XC9140A), and also a bypass mode function to maintain continuity between the input and output (XC9140C).
A version with a UVLO (Under Voltage Lock Out) function will also be available (currently under development) which enables the prevention of battery leakage by stopping the IC’s operation when the input voltage is low. The standard product will have a UVLO release voltage of 2.15V (±3.0%) and a custom version with a UVLO release voltage selectable from between 1.65V to 2.2V, in steps of 0.05V, will also be made available.
|Aug 1, 2012||
|Step-up Synchronous PFM DC/DC Converter XC9140 Series|
Typical Application Circuit
|Input Voltage Range||0.9V~5.5V|
|Output Voltage Range||1.8V~5.0V(±2.0%), (0.1V increments)|
|Output Current||100mA@VOUT=3.3V, VBAT=1.8V(TYP.|
|Driver Transistor||0.6Ω(N-ch driver transistor)
0.65Ω(P-ch Switching Transistor)
|High Speed Transient||50mV@VOUT=3.3V, VBAT=1.8V, IOUT=1→100mA|
|PFM Switching Current||350mA|
|Functions||Load Disconnection Function
Bypass Mode Function
|Operating Ambient Temperature||-40℃～+85℃|
|Environmentally Friendly||EU RoHS compliant, Pb free|
|Package||SOT-25||Number of Pins||5|
|Pcs/Reel||3,000||Package Size(mm)||2.8 x 2.9 x 1.3|
|Package||USP-6EL||Number of Pins||6|
|Pcs/Reel||3,000||Package Size(mm)||1.8 x 2.0 x 0.4|
How does the CL discharge function work?
The function rapidly releases the charge remained in the CL capacitor to make the VOUT pin voltage zero. The VOUT pin voltage does not reach zero immediately after being turned off by the CE function due to the charge remained in the connected CL capacitor. While the charge in the CL capacitor is gradually reaching zero, the LSI continues operating and does not work with the CE pin signal, which may cause a malfunction. This is why the discharge is required when turning off the CE pin. A larger capacitance of the capacitor needs longer time to be discharged.
What does CL mean?
Load capacitor. Other companies often refer to it as COUT.
What is the standby current?
The current that flows through the IC in the standby mode. The standby mode means the state where the IC has been turned off by the CE function.
What does the FB product mean?
An IC for which any output voltage can be set by the reference voltage of the FB pins and the external dividing resistor. The output voltage is determined by the RFB1 and RFB2 values, using the following formula: VOUT = Vref × (RFB1 + RFB2)/RFB2
How does UVLO (under voltage lockout) work?
This circuit forcibly turns off the driver transistor when VIN drops below the UVLO voltage. If the input voltage recovers to the value which is equal to the specified value or more, UVLO will be released to resume the switching operation. It is resumed by the soft-start function. The paused state by UVLO is not the shutdown. The pulse output is stopped, but the internal circuit is operating.