AT1367A Datasheet, PDF (10/14 Pages) Aimtron Technology – 1MHz, 800mA Synchronous Buck Converter With Power Good Detector & LDO

AT1367A/B/C/D
Preliminary Product Information
1MHz, 800mA Synchronous Buck Converter
With Power Good Detector & LDO
efficiency when selecting an inductor. The inductor is selected to limit the ripple
current to some predetermined value, typically 20~40% of the full load current at the
maximum input voltage. The formula of inductance value is as below:
∆I _L = 0.2 ~ 0.4 × I_{OUT (MAX )}
L=
V_OUT
f × ∆I_L
¹
−
V_OUT
V_IN

I _PK
= I_O
+ ^{∆I L}
2
= I_O
+ ^(VIN
− V_OUT ) × t_ON
2× L
Power Good Indicator with Adjustable Time Delay
The PG and /PG pin terminal is an open drain output of N-MOS. Connect a resistor
from PG and /PG pin to VCC or OUT1 to create a logic signal. If OUT1 pin is less
than 2.97V (typ.) this pin is pulled to ground. When OUT1 pin is above 2.97V and
with a delay time this pin is open. PG and /PG pin is forced low when in UVLO. The
formula of adjustable delay time is as below :
delay − time = C × ^0.8
I _DELAY
The Dissipation
The power loss is given by:
P_{LOSS (DC−DC)}
=
I × R 2
OUT1
DS (ON )−P
×
D
+
I2
OUT1
×
R_{DS (ON )−N}
× (1 − D) + V_IN
× I _OUT1 × (t_r
+t_f
)×
f_s
+
I_s
× V_IN
P_{LOSS (LDO)} = I _{OUT 2} × (V_OUT1 − V_{OUT 2} )
θ T_{J (MAX )} = T_A + _JA × (P_{LOSS (DC −DC )} + P ) _{LOSS (LDO)}
7F, No.9, Park Avenue II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone] Fax: [phone]
WWW: http://www.aimtron.com.tw
3/2/2006 REV:1.2
Email: [e-mail]
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