Step-Up DC/DC Controller, MAXDUTY: 93%
XC9121 Series are PWM control step-up DC/DC converter controller ICs. Since maximum duty ratio is as large as 93%, the series is the best for the applications used as high step-up ratios, such as the LCD panels and OELD. In this series, even if it is a high step-up ratio, the output voltage stabilized at high efficiency can be obtained. With 0.9V (±2.0%) of reference voltage supply internal, and using external resistors, RFB1 and RFB2, output voltage can be set up freely within a range of 1.5V to 30V.
For a current sense, with the use of RSENSE, ceramic capacitors can be used as load capacitors and allows for lower output ripple and reduced PCB area requirements.
During stand-by (when the CE pin is low), all circuits are shutdown to reduce current consumption to as low as 1.0μA or less.
The overcurrent limit circuit of this IC is designed to monitor the ripple voltage of the FB pin and operates the IC to stop when the ripple voltage runs over 250mV. The IC resumes its operation with a toggle of the CE pin or by turning the power supply back on.
Typical Application Circuit
|Input Voltage Range||0.9V～6.0V|
|Power Supply Voltage Range||1.8V～6.0V|
|Output Voltage Range||1.5V～30V,Can be set freely with 0.9V(±2.0V) of reference voltage supply and external registors.|
|Output Current||More than 80mA(VIN=3.6V,VOUT=15V)|
|Control Methods||PWM/PFM automatic switching control|
|Load Capacitors||Low ESR capacitors compatible|
|Current Limiter Function||Operates when ripple voltage=250mV|
|Package||SOT-25||Number of Pins||5|
|Pcs/Reel||3,000||Package Size(mm)||2.8 x 2.9 x 1.3|
|Package||USP-6C||Number of Pins||6|
|Pcs/Reel||3,000||Package Size(mm)||1.8 x 2.0 x 0.6|
How does the GO function of DC/DC converters work? Does it work just like a regulator?
Torex regard the PWM/PFM automatic switch control function as Green Operation (GO) in the case of DC/DC. The GO function is defined as the switching operation between the PFM mode for a small output current and the PWM mode for a large output current. The PFM control method controls the output current by increasing and decreasing the fall time according to the output current while keeping a pulse width. The PWM control method controls the output current by adjusting the pulse width of the rise time, which keeps the rise/fall time interval constant and increases the efficiency at a heavy load. By switching between the PFM control for a small output current and the PWM control for a large output current, the quiescent current can be controlled for both of heavy and light loads.
What is the soft-start function?
The function to soften the rise to prevent the inrush current.
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