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PDF LA8521 Data sheet ( Hoja de datos )
| Número de pieza | LA8521 | |
| Descripción | 5A/23V Step-Down DC-DC Converter | |
| Fabricantes | INNO-TECH | |
| Logotipo |  |
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General Description
LA8521
300KHz, 5A/23V Step-Down DC-DC Converter
Features
LA8521 is a voltage mode, step-down DC-DC
converter that is designed to meet 5A output
current, and utilizes PWM control scheme that
switches with 300KHz fixed frequency.
The input voltage range of LA8521 is from 3.6V
to 23V, and available in adjustable output
voltage from 0.8V to VIN. The supply current is
only 3mA during operation and under 1uA in
shutdown.
This device provides an enable function that
can be controlled by external logic signal. It
also provides excellent regulation during line
or load transient. Other features of current
limit, thermal shutdown protection, and short
circuit protection are also included. Due to the
low RDS(ON) of the internal power MOSFET, this
device provides high efficiency step-down
applications. It can also operate with a
maximum duty cycle of 100% for use in low
drop-out conditions. The package is available
in standard ESOP-8.
l Adjustable Output Voltage from 0.8V to VIN
l 3.6V to 23V Input Voltage Range
l Continuous 5A Output Capability
l 300KHz Oscillation Frequency
l 0.8V Reference Voltage
l 1uA Low Shutdown Current
l 3mA Low Supply Current
l 100% Duty Cycle
l Built-in Low RDS(ON) Power MOSFET
l No External Compensation Required
l Adjustable Current Limit
l Short Circuit Protection
l Thermal Shutdown Protection
l ESOP-8 Package
l Meet RoHS Standard
Applications
l Broadband Communication Device
l LCD TV / Monitor
l Storage Device
l Wireless Application
Ordering Information
LA8521 1 2 3 4
1 (Package Type) => P: ESOP
2 (Number of Pins) => G: 8 pin
3 (Output Voltage) => Blank: Adjustable
4 (Special Feature) => Blank: N/A
Available Part Number
LA8521PG
Marking Information
LA8521PG
1234
1 2 (Date Code)
For date code rule, please contact our sales
representative directly.
3 4 (Internal Code)
Rev01
-1-
Mar. 07, 2013
www.inno.com.tw
1 page  
LA8521
Absolute Maximum Ratings
Parameter
Input Voltage
SW Pin Voltage Range
FB Pin Voltage Range
EN Pin Voltage Range
Storage Temperature Range
Junction Temperature
Lead Soldering Temperature (10 sec)
Rating
25V
-0.5V ~ VIN+0.5V
-0.3V ~ VIN
-0.3V ~ VIN+0.3V
-65°C ~ 150°C
150°C
300°C
These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for
prolonged time periods may affect device reliability. All voltages are with respect to ground.
Recommended Operating Conditions
Parameter
Input Voltage Range
Ambient Temperature Range
Junction Temperature Range
Rating
3.6V ~ 23V
-40oC ~ 85oC
-40oC ~ 125oC
These are conditions under which the device functions but the specifications might not be guaranteed. For
guaranteed specifications and test conditions, please see the Electrical Specifications.
Package Information
Parameter
Thermal Resistance
(Junction to Case)
Thermal Resistance
(Junction to Ambient)
Package
ESOP-8
Symbol
θJC
θJA
Rating
10 oC/W
50 oC/W
Rev01
-5-
Mar. 07, 2013
www.inno.com.tw
5 Page 
LA8521
the EN pin threshold voltage, the device will start to operate. The start-up delay time can be
calculated by the following formula:
VIN
RDELAY
IN
EN GND
CDELAY
VEN
VIN x (1 – e-T/(RxC)) > VEN
Where T is the start-up delay time, R is RDELAY, C is CDELAY, and the typical VEN is 1.3V.
This feature is useful in situations where the input power source is limited in the amount of current
it can deliver. It allows the input voltage to rise to a higher voltage before the device starts
operating.
Snubber Circuit
The simple RC snubber is used for voltage transient and ringing suppression. The high frequency
ringing and voltage overshooting at the SW pin is caused by fast switching transition and
resonating circuit parasitical elements in the power circuit. It maybe generates EMI and interferes
with circuit performance. Reserve a snubber circuit in the PC board is preferred to damp the
ringing due to the parasitical capacitors and inductors of layout. The following circuit is a simple RC
snubber:
SW
FB
GND
C SN UB
RSNUB
VOUT
Choose the value of RC network by the following procedure:
(1) Measure the voltage ringing frequency (fR) of the SW pin.
(2) Find a small capacitor and place it across the SW pin and the GND pin to damp the ringing
frequency by half.
(3) The parasitical capacitance (CPAR) at the SW pin is 1/3 the value of the added capacitance
above. The parasitical inductance (LPAR) at the SW pin is:
1
LPAR = (2πfR)2 × CPAR
(4) Select the value of CSNUB that should be more than 2~4 times the value of CPAR but must be
small enough so that the power dissipation of RSNUB is kept to a minimum.
Rev01
- 11 -
Mar. 07, 2013
www.inno.com.tw
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet LA8521.PDF ] | |
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