TB7101F(T5L1.2,F) , TB7101F(T5L1.5,F)

TB7101F(T5L1.8,F) , TB7101F(T5L2.5,F)

TB7101F(T5L3.3,F)

2007-09-06

11

H

V

V

mA

MHz

V

V

V

V

I

f

V

V

L

IN

OUT

L

OSC

OUT

IN

μ

7

.

3

5

3

.

3

300

1

3

.

3

5

=

⋅

⋅

−

=

⋅

Δ

⋅

−

=

Figure 2: Inductor current waveform

Output capacitor

The capacitance of the output ceramic capacitor is greatly affected by temperature. Select a product whose

temperature characteristics (such as B-characteristic) are excellent. The capacitance value should be to more than 10

μF,

and set to an optimum value by, for example, enlarging the output capacitor when there is instability under use

conditions ,or when there is a large ripple voltage or drop in output voltage under heavy loads. Ceramic capacitors can

be used to achieve low output ripple, though it is more difficult to achieve phase compensation with ceramic capacitors

because the equivalent series resistance (ESR) of ceramic capacitors is lower. For this reason, perform a careful

evaluation when using ceramic capacitors.

Precautions

• Please select parts after confirming the actual operation in the customer set and considering the input voltage the

output voltage, the output current, the temperature, the characteristics or the kind of capacitor, and the inductor.

• If the voltage between the input and output is low, the influence of the on-state voltage of the switch power

MOSFET is greater, causing the voltage across the inductor to decrease. For this reason, it may become

impossible for the required inductor current to flow, resulting in lower performance or unstable operation of the

DC-DC converter. As a rough standard, keep the input-output voltage potential difference at or above 1 V, taking

the on-state voltage of the power MOSFET into consideration.

• The lowest output voltage that can be set is 0.8 V (typ.).

between the SGND pin and the VIN pin.

OSC

f

1

T

=

IN

OUT

ON

V

V

T

T

⋅

=

0

Δ

IL