TB7101AF(T5L1.2,F)/(T5L1.5,F)/(T5L1.8,F)/(T5L2.5,F)/(T5L3.3,F)

2008-05-22

10

Application Circuit Example

Figure 1

TB7101AF(T5L*.*,F) Application Circuit Example

These values are presented only as a guide.

Input filter capacitor = 10

μF

(ceramic capacitor: GRM21BB30J106K from Murata Manufacturing Co., Ltd.)

(ceramic capacitor: GRM21BB30J106K from Murata Manufacturing Co., Ltd.)

L:

Inductor = 3.3

μH (NP04SB3R3N from Taiyo Yuden Co., Ltd.)

These values are presented only as a guide.

Input filter capacitor = 10

μF

(ceramic capacitor: GRM21BB30J106K from Murata Manufacturing Co., Ltd.)

(ceramic capacitor: GRM31CB30J226K from Murata Manufacturing Co., Ltd.)

L:

Inductor = 3.3

μH (NP04SB3R3N from Taiyo Yuden Co., Ltd.)

Component values need to be adjusted, depending on the TB7101AF’s input/output conditions and the board layout.

Application Notes

Inductor Selection

The inductance required for inductor L can be calculated as follows:

IN

OUT

L

osc

OUT

IN

V

V

I

f

V

V

L

⋅

Δ

⋅

−

=

········· (1)

: Input voltage (V)

: Oscillation frequency

= 1 MHz (typ.)

: Inductor ripple current (A)

*: Generally,

ΔIL should be set to approximately 30% of the maximum output current. Since the maximum output

current of the TB7101AF is 1 A,

ΔIL should be 0.3 A or so. Therefore, the inductor should have a current rating

greater than the peak output current of 1.15 A. If the inductor current rating is exceeded, the inductor becomes

saturated, leading to an unstable DC-DC converter operation.

select an appropriate inductor, taking the VIN range into account.

PGND

TB7101AF (T5L*.*, F)

SGND

GND

GND

EN

L