|
|
Número de pieza | BM1410A | |
Descripción | 2.2A Step-Down Converter | |
Fabricantes | bookly | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de BM1410A (archivo pdf) en la parte inferior de esta página. Total 8 Páginas | ||
No Preview Available ! 2.2A Step-Down Converter
BM1410A
FEATURES
2.2A Output Current
Efficiency up to 92% @+5V output
+5V to +23V Input Range
15µA Shutdown Supply Current
380kHz Switching Frequency
Adjustable Output Voltage from 1.23V to 0.85*VIN
Cycle-by-Cycle Current Limit Protection
Thermal Shutdown Protection
Frequency Fold Back at Short Circuit
Stability with Wide Range of Capacitors,
full pin-pin with ACT4060/ TD1410 / MP1410
SOP-8 Package
APPLICATIONS
TFT LCD Monitors
Portable DVDs
NET CARD
Telecom Power Supplies
DSL and Cable Modems and Routers
LCD TV
GENERAL DESCRIPTION
The BM1410A is a current-mode step-down
DC-DC converter that generates up to 2.2A output
current at 380kHz switching frequency. The device
utilizes advanced BCD process for operation with
input voltage up to +23V consuming only 15µA in
shutdown mode, the BM1410A is highly efficient
with peak efficiency at 92% when in operation.
Protection features include cycle-by-cycle
current limit, thermal shutdown, and frequency fold
back at short circuit.
The BM1410A is available in SOP-8
package and requires very few external
devices for operation.
It can replace ACT4060/MP1410 without
change external components and PCB layout.
In application , if not use the pin7(en)
function , can let the pin7 open , can pull-up to Vin
with a pull-up resistor, but can not short to Vin
dirrectly.
+5V to 20V
ENABLE
F1
BS
2 IN
SWSW 3
7 EN ABCCMTX14440016060A0 FFBB 5
GnGd CCOOMMPP
46
2.5V/2A
www.bookly.com
Figure 1. Typical Application Circuit
1
1 page BM1410A
APPLICATION INFORMATION
OUTPUT VOLTAGE SETTING
Vout
RFB1
FB
RFB2
Figure 3. Output Voltage Setting
Figure 3 shows the connections for setting
the output voltage. Select the proper ratio of the
two feedback resistors RFB1 and RFB2 based on
the output voltage. Typically, use RFB2 ≈10kΩ
and determine RFB1 from the output voltage:
RFB1
=
RFB
2
⎛
⎜⎝
VOUT
1.225V
−1⎞⎟⎠
(1 )
INDUCTOR SELECTION
The inductor maintains a continuous current
to the output load. This inductor current has a
ripple that is dependent on the inductance value:
higher inductance reduces the peak-to-peak
ripple current. The trade off for high inductance
value is the increase in inductor core size and
series resistance, and the reduction in current
handling capability. In general, select an
inductance value L based on ripple current
requirement:
L = VOUT • (VIN −VOUT )
V f I KIN SW OUTMAX RIPPLE
(2 )
where VIN is the input voltage, VOUT is the output
voltage, fSW is the switching frequency, IOUTMAX is
the maximum output current, and KRIPPLE is the
ripple fCXor. Typically, choose KRIPPLE = 30% to
correspond to the peak-to-peak ripple current
being 30% of the maximum output current.
With this inductor value (Table 1), the peak
inductor current is IOUT • (1 + KRIPPLE / 2).
Make sure that this peak inductor current is less
that the 3A current limit. Finally, select the
inductor core size so that it does not saturate at 3A.
Table 1. Typical Inductor Values
Vout 1.5v 1.8v 2.5v
L(µH) >=6.8 >=6.8 >=10
3.3v
>=15
5v
>=22
12v
>=47
INPUT CAPACITOR
The input capacitor needs to be carefully selected to
maintain sufficiently low ripple at the supply input of the
converter. A low ESR capacitor is highly recommended.
Since large current flows in and out of this capacitor
during switching, its ESR also affects efficiency.
The input capacitance needs to be higher than 10µF.
The best choice is the ceramic type; however, low ESR
tantalum or electrolytic types may also be used provided
that the RMS ripple current rating is higher than 50% of
the output current. The input capacitor should be placed
close to the IN and G pins of the IC, with shortest traces
possible. In the case of tantalum or electrolytic types,
they can be further away if a small parallel 0.1µF ceramic
capacitor is placed right next to the IC.
OUTPUT CAPACITOR
The output capacitor also needs to have low ESR to
keep low output voltage ripple. The output ripple voltage
is:
V RIPPLE = IOUTMAX KRIPPLE RESR
+
VIN
28 |