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NInput Voltage Range : 2.0V ~10.0V NOutput Voltage Range : 2.4V ~ 6.0V (2.5% accuracy) NOscillation Frequency Range : 180kHz, 300kHz (15% accuracy) NMaximum Duty Ratio : 85% (typ) NPWM/PFM Switching Step-Up & Down Control (XC9302) NEfficiency NSOT-25 Package : 81% (typ) 5.0V , 78% (typ) 3.3V
GMobile phones GPDAs GPalmtop computers GPortable audio equipment GVarious power supplies
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The XC9301/02 series are step-up/down DC/DC converter controller ICs with fast, low ON resistance drivers built-in. A versatile, large output current, step-up/down DC/DC converter can be realised using only 4 basic external components - transistors, coils, diodes and capacitors. Output voltage is selectable in 0.1V steps within a 2.4V ~ 6.0V ( 2.5% accuracy) range and switching frequency is set at 180kHz or 300KHz. The XC9302 series switches from PWM to PFM control during light loads and the series offers high efficiencies from light loads through to large output currents. Soft-start time is internally set to 10 msec which offers protection against rush currents when the power is switched on and also against voltage overshoot. During shutdown (CE pin = L), consumption current can be reduced to as little as 0.5A or less. Input Voltage Range : 2.0V ~ 10V Output Voltage Range : 2.4V ~ 6.0V ( 2.5% accuracy) (selectable in 0.1V steps) Oscillation Frequency : 180KHz, 300KHz ( 15% accuracy) Output Current : more than 250mA (VIN=2.4V, Efficiency Stand-By VOUT=3.3V) : 81% (typ) at 5.0V, 78% (typ) at 3.3V : ISTB = 0.5A (max)
Output Voltage Internal Set-Up SOT-25 Package
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GOrdering Information
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GSOT-25
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q
qwer
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e
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r
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6
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XC9301x332MR,XC9302x332MR
XC9301x333MR, XC9302x333MR
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GCircuit Connection Example
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The XC9301/9302 series are PWM (PWM/PFM switching) step-up/down DC/DC converter controller ICs. The XC9302 series switches to PFM operations during light loads and is very efficient over a wide range in relation to load. Further, the efficiency can be maintained over a wide input voltage range as both step-up & step-down operations are PWM controlled. Output voltage settings are laser trimmed. [ON TIME] P-Ch MOSFET (PSW) = ON, N-Ch MOSFET (NSW) = ON : Current flows from VIN via PSW, L, NSW, to GND : L is charged. [OFF TIME] P-Ch MOSFET (PSW) = OFF, N-Ch MOSFET (NSW) = OFF : Current flows from GND via SD1, L, SD2, to VOUT : VOUT rises due to the charge stored at L. By comparing VOUT with the internal reference voltage, the ON TIME vs OFF TIME ratio can be regulated & output stability can be protected.
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Block Diagram Explanation The error amplifier is used as an output voltage monitor. It compares the reference voltage with the feedback from the voltage divided by the internal resistor. Should a voltage higher than the reference voltage be fedback, the output of the error amp will increase. The PWM comparator compares the output of the error amp with the ramp wave. When the voltage at the output of the error amp is low, the EXT/ pin will be LOW level (Switching ON time). The ramp wave generator, as the name suggests, generates the switching frequency's ramp wave. With the XC9302 series, control is automatically switched between PWM and PFM according to the size of the load. The start up of the Vref voltage at the error amp's input is gradual due to the internal capacitor and low current circuit. Because of this soft-start function, the operations of the error amp's 2 inputs are balanced and the EXT/ pin's ON time can be manipulated to produce longer ON times. Further, with the UVLO function, the signal will be such so as not to turn the MOS switch ON until any instability in the internal circuit stabilizes during soft-start time. Even in cases where input voltage is so low as to produce instability in the IC, the UVLO function will operate and the MOS switch will be turned OFF.
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GProduct Selection (Notes)
XC9301/02 series is a group of PFM controlled (XC9302 series switches from PWM to PFM control during light loads) step-up and down DC/DC converters. The series is highly efficient with a wide range of input voltage since its stepping-up and down operation is controlled by PWM movements. In general, there are several methods available for obtaining a stable output voltage at such times when input voltage is changing from being higher than the established output voltage to being lower than the established output voltage. Each method has its merits and demerits but is essential that a method which provides the best results in terms of input & output under actual operating conditions. Below, two methods are highlighted and their respective performances in terms of efficiency are compared. This is an efficiency comparison of two ways, step-up DC/DC converter + VR and step-up & down DC/DC converter.
[Step-up DC/DC Converter + VR] (XC6361/62)
N Step-up mode (Input voltage < set output voltage + 0.4V) After input voltage has been stepped-up to set output voltage + 0.4V by the step-up DC/DC converter, the output voltage will be regulated to the set value by the VR. (0.4V loss via the VR) N Step-down mode (Input voltage > set output voltage + 0.4V) After input voltage has been stepped-up to set output voltage + 0.4V by the step-up DC/DC converter, the output voltage will be regulated to the set value by the VR. (Input/Output voltage difference loss via the VR)
[Step-up&down DC/DC Converter] (XC9301/02)
N Set ouput voltage obtained as a result of the automatic switching operations of the IC regardless of the difference between input voltage and set output voltage.
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The above graph shows that over a wide input voltage range, the efficiency of the XC9301/02 is more or less constant. On the other hand, the efficiency of the XC6361/62 is clearly shown to decrease as input voltage increases. In step-down mode in particular, the efficiency of the XC9301/02 is much better than the XC6361/62. In applications that use either a standard dry 3 cell battery or a 2 cell lithium Ion battery to obtain an output of 3.3V, for example, the efficiency of the XC9301/02 series is again much better. Because the XC9301/02 series does not have a series regulator output, we recommend a test with samples for use in applications where ripple voltage is a problem.
GExternal Components Selection (Notes)
GThe performance of the DC/DC converter IC circuit is heavily reliant upon the performance of the surrounding circuitry and components. In particular, since the VF voltage of the Schottky Diode used will have a direct effect upon efficiency, the smaller the diode, the better the efficiency obtainable. (Refer to the graph below) GIt is also recommended that a switching MOSFET with a small ON resistance be used. With the XC9301/02, an ON resistance of 500m or less is recommended.
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GDemo Board ver. 1.1
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JP3 : Must be connected JP2 : To be connected if using SW (CE pin fixed to VIN) * Use tinned copper wire for VIN pin, VOUT pin, GND pin, JP2, and JP3. * Connect test pins for TP1, TP2, TP3, and CE.
Note:
Oscillation may occur as a result of input voltage instability when the output current is large. At such times, we recommend that in place of the 220F PJ type capacitor, you connect R1 & C1 as shown in the diagram below. (In case of demo boards ver. 1.1, cut the pattern wire of R1 connecting point, then connect R1.)
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XC9302A332 (PWM/PFM switching control, 180kHz, VOUT=3.3V) (1) OUTPUT VOLTAGE vs. OUTPUT CURRENT (Topr=25C)
(2) EFFICIENCY vs. OUTPUT CURRENT (Topr=25C)
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(3) RIPPLE VOLTAGE vs. OUTPUT CURRENT (Topr=25C)
External Components PSW : XP162A12A6PR NSW : XP161A1265PR SD L : U2FWJ44N : 22H (CR54) 2 CL CIN RDD CDD : 47F (Tantalum MCE) : 10 : 47F (Tantalum MCE) 2 : 220F (Electrolytic PJ type)
VCE=VIN
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(4) LOAD TRANSIENT RESPONSE (Topr=25C)
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External Components PSW : XP162A12A6PR NSW : XP161A1265PR SD L : U2FWJ44N : 22H (CR54) 2 CL CIN RDD CDD : 47F (Tantalum F93) : 10 : 22F (Tantalum) 2 : 220F (Al. Electrolytic PJ type)
VCE=VIN
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XC9302A502 (PWM/PFM switching control, 180kHz, VOUT=5.0V) (1) OUTPUT VOLTAGE vs. OUTPUT CURRENT (Topr=25C)
(2) EFFICIENCY vs. OUTPUT CURRENT (Topr=25C)
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(3) RIPPLE VOLTAGE vs. OUTPUT CURRENT (Topr=25C)
External Components PSW : XP162A12A6PR NSW : XP161A1265PR SD L : U2FWJ44N : 22H (CR54) 2 CL CIN RDD CDD : 47F (Tantalum MCE) : 10 : 47F (Tantalum MCE) 2 : 220F (Electrolytic PJ type)
VCE=VIN
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(4) LOAD TRANSIENT RESPONSE (Topr=25C)
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External Components PSW : XP162A12A6PR NSW : XP161A1265PR SD L : U2FWJ44N : 22H (CR54) CL CIN RDD CDD : 47F (Tantalum F93) : 10 : 47F (Tantalum) 2 : 220F (Electrolytic PJ type)
VCE=VIN
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