Rev. 0.05 - 10 -
G
In terms of the capacitor for setting delay time of the latch protection, C2 as shown in typical applications of the
previous page, connect between Delay pin and GND pin of the IC with the minimum wiring distance.
G
Connect a 1
μ
F or more value of capacitor between V
OUT
and GND, C3 as shown in typical applications of the
previous page. (Recommended value is from 10
μ
F to 22
μ
F.)
G
Connect a capacitor between V
OUT
and the dividing point, C4 as shown in typical applications of the previous page.
The capacitance value of C4 depends on divider resistors for output voltage setting. Typical value is between 100pF
and 1000pF.
G
Output Voltage can be set with divider resistors for voltage setting, R1 and R2 as shown in typical applications of
the previous page. Refer to the next formula.
Output Voltage = V
FB
×
(R1+R2)/R2
R1+R2=100k
is recommended range of resistance.
G
We recommend adding a resistor with resistance value from 20k
to 100k
between divider point of voltage
setting and V
FB
pin, R3 as shown in typical applications of the previous page. If R3 is not connected as shown, the
noise of V
OUT
could be transmitted to V
FB
input and accuracy of output voltage could be worse.
G
The operation of Latch protection circuit is as follows: When the IC detects maximum duty cycle, charge to an
external capacitor, C2 of DELAY pin starts. And maximum duty cycle continues and the voltage of DELAY pin
reaches delay voltage detector threshold, V
DLY
, outputs “L” to EXT pin and turns off the external power MOSFET.
To release the latch protection operation, make the IC be standby mode with CE pin and make it active in terms of
B/D version. Otherwise, restart with power on.
The delay time of latch protection can be calculated with C2, V
DLY
, and Delay Pin Charge Current, I
DLY1
, as in the
next formula.
t=C2
×
V
DLY
/I
DLY1
Once after the maximum duty is detected and released before delay time, charge to the capacitor is halt and delay
pin outputs “L”.
G
As for A/C version, connect a capacitor between AMPOUT pin and V
FB
pin and a resistor for phase compensation,
C5 and R4 as shown in typical applications of the previous page. The resistance value of R4 is as same as R3. The
recommended capacitance value of C5 is between 1nF and 10nF.
Recommended value of R3 is from 20k
to 100k
.
G
As for B/D version, EXT pin outputs GND level at standby mode.
G
Select the Power MOSFET, the diode, and the inductor within ratings (Voltage, Current, Power) of this IC. Choose
the power MOSFET with low threshold voltage depending on Input Voltage. Choose the diode with low V
F
such as
Shottky type, and with low I
R
.