XC9502 Series
2ch. Step-up / down DC/DC Controller ICs
<Setting of Output Voltage>
Output voltage can be set by adding external split resistors. Output voltage is determined by the following equation, based on the
values of RFB11(RFB21) and RFB12(RFB22). The sum of RFB11(RFB21) and RFB12(RFB22) should normally be 1 M
Ω
or less.
V
OUT
=0.9
×
(RFB11+RFB12) /RFB12
The value of CFB1(CFB2), speed-up capacitor for phase compensation, should be fzfb= 1 / (2
× π ×
CFB1
×
RFB11) which is
equal to 12kHz. Adjustments are required from 1kHz to 50kHz depending on the application, value of inductance (L), and value of
load capacity (CL).
[Example of Calculation]
When RFB11=200kΩ and RFB12=75kΩ, V
OUT1
=0.9
×
(200K+75k) / 75k=3.3V.
[Typical Example]
VOUT RFB11 RFB12 CFB1
(V)
(pF)
(kΩ)
(kΩ)
VOUT RFB11 RFB12 CFB1
(V)
(pF)
(kΩ)
(kΩ)
VOUT RFB11 RFB12 CFB1
(V)
(pF)
(kΩ)
(kΩ)
2.5
390
220
8.0
120
15
100
30
270
430
33
33
13
82
220
330
62
2.7
360
180
12.0
160
3.0
560
240
24
220
220
62
3.3
200
75
62
330
270
39
390
270
33
5.0
82
18
160
The same method can be adopted for channel two (output 2) also.
[External Components]
Output 1 (Step-up DC/DC controller)
Output 2 (Step-down DC/DC controller)
1.0
1.5
1.8
2.0
2.2
Tr 1 :
(TOREX N-Channel Power MOSFET)
Note : VGS Breakdown Voltage of this Tr. is 8V so
please be careful with the power supply voltage. For 6V
power supply voltage, XP161A1265PR which VGS
breakdown voltage is 12V is recommended.
VST1 of XP161A1355PR is 1.2V (max.) and that of
XP161A1265PR is 1.5V (max.)
* MOSFET
XP161A1355PR
Tr 2 :
* MOSFET
XP162A12A6P
(TOREX P-Channel Power MOSFET)
Note : VGS Breakdown Voltage of this Tr. is 12V so
please be careful with the power supply voltage.
SD 1 : MA2Q737
(Schottky , MATSUSHITA)
CMS02
(Schottky, TOSHIBA)
L 1:
10µH
(SUMIDA, CDRH5D28, FOSC = 500kHz)
15µH
(SUMIDA, CDRH5D28, FOSC = 300kHz)
22µH
(SUMIDA, CDRH5D28, FOSC = 180kHz)
CL1 : 16V, 47µF
(Tantalum)
Increase capacity according to the equation below
when the step-up voltage ratio is large and output
current is high.
C=(CL standard value)×(IOUT1(mA)/300mA×VOUT1/VIN
SD 2 : MA2Q737
(Schottky , MATSUSHITA)
CMS02
(Schottky, TOSHIBA)
L 2:
10µH
(SUMIDA, CDRH5D28, FOSC = 500kHz)
22µH
(SUMIDA, CDRH5D28, FOSC = 300kHz)
47µH
(SUMIDA, CDRH5D28, FOSC = 180kHz)
CL2 : 16V, 47µF
(Tantalum)
Increase capacity according to the equation below
when the step-up voltage ratio is large and output
current is high.
C=(CL standard value)×(IOUT2 (mA)/500mA×VOUT2/VIN
Tr :
* NPN MOSFET
2SD1628 (SANYO)
RB 1 : 500Ω ( Adjust in accordance with load & Tr.'s HFE.)
Set according to the equation below.
RB1
≤
(VIN-0.7) x hFE / I
C
-R
EXTBH
CB1 :
2200pF (Ceramic)
Set according to the equation below.
CB1
≤
(2
π
x RB2 x FOSC x 0.7)
* PNP MOSFET
2SA1213
(SANYO)
RB 2 : 500Ω
( Adjust in accordance with load & Tr.'s HFE.)
Set according to the equation below.
RB2
≤
(VIN-0.7) x hFE / I
C
-R
EXTBH
CB1 :
2200pF (Ceramic)
Set according to the equation below.
CB2
≤
(2
π
x RB2 x FOSC x 0.7)
Tr :
8
TOREX [ TOREX SEMICONDUCTOR ]
