Preliminary

Functional Settings

< Output Voltage Setting>

fzfb = 30kHz (L=10

µH)

RFB1 : 270k

Ω

RFB2 : 30k

Ω

fzfb = 20kHz (L=22

µH)

CFB :

20pF

(fzfb = 30kHz, L = 10

µH)

fzfb = 10kHz (L=47

µH)

27pF

(fzfb = 20kHz, L = 22

µH)

56pF

(fzfb = 10kHz, L=47

µH)

< The use of ceramic capacitor CL >

Recommended Components

Tr:

*When a MOSFET is used :

*When a NPN Tr. Is used :

2SK2159 (NEC N-Channel Power MOSFET)

2SD1628 (Sanyo)

Rb

: 500

Ω (adjust with Tr's HFE or load)

Cb

: 2200pF (ceramic type)

Cb

≤ 1 / (2π × Rb× FOSC × 0.7)

SD:

MA2Q737 (Schottky Diode type, MATSUSHITA)

L, CL :

Adjust as below according to the condition and peripheral components

When Ceramic capacitor is used :

L :

22

µH (SUMIDA CDRH5D28, FOSC = 100kHz)

10

µH (SUMIDA CDRH5D18, FOSC = 300kHz)

CL :

10V 10

µF (Ceramic capacitor, LMK325BJ106ML, TAIYOYUDEN)

Use the formula below when step-up ratio and output current is large.

CL = (CL standard value)

RSENSE : 100m

Ω

(FOSC = 300kHz)

Look up "Low Chip Resistor" for the selection

50m

Ω

(FOSC = 100kHz)

When Tantalum condenser is used :

L:

22

µH (SUMIDA CDRH5D28, FOSC = 300kHz)

47

µH (SUMIDA CDRH5D28, FOSC = 100kHz)

CL:

16V 47

µF (tantalum type NIPPONCHEMI 16MCE476MD2)

Use the formula below when step-up ratio and output current is large.

CL = (CL standard value)

RSENSE:

Not required, but short out the wire.

When AL Electrolytic condenser is used :

L:

22

µH (SUMIDA CDRH5D28, FOSC = 300kHz)

47

µH (SUMIDA CDRH5D28, FOSC = 100kHz)

CL:

16V 100

µF (AL electrolytic type) + 10V 2.2µF (ceramic type)

Strengthen appropriately when step-up ratio and output current is large.

RSENSE:

Not required, but short out the wire.

CFB:

Set up so that fzfb = 100kHz.

6

Output voltage can be set by adding external split resistors. Output voltage is determined by the following equation, based on the values

of RFB1 and RFB2. The sum of RFB1 and RFB2 should normally be 2 M

varied externally from 0.8V to 2.5V.

PWM Control, PWM/PFM Switching Control,

Step-up DC/DC Converters

Externally Applied Reference Voltage (Vref)

Note* : With direct voltages over 4.5V, use the

XP161A11A1PR.

The value of CFB1, speed-up capacitor for phase compensation, should result in fzfb = 1/(2

π × CFB × RFB1) equal to 5 to 30kHz.

Adjustments are required depending on the application, value of inductance (L), and value of load capacity (CL).

The circuit of the XC9106/9107 series is organized by a specialized circuit which reenacts negative feedback of both voltage and

current. Also by insertion of approximately 100m

Ω of a low and inexpensive sense resistor as current sense, a high degree of

stability is possible even using a ceramic capacitor, a condition which used to be difficult to achieve. Compared to a tantalum

condenser, because the series can be operated in a very small capacity, it is suited to use of the ceramic capacitor which is cheap

and small.

XC9106 / 07 Series