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ETA1485
3A, 18V High Efficiency Synchronous Step-Down Converter
DESCRIPTION
The ETA1485 is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of delivering up to 3A of output current. Current mode PWM control allows the use of small external components, such as ceramic input and output caps, as well as small inductors, while still providing low output ripples. On top of the integrated internal synchronous rectifier that eliminates external Schottky diode, ETA1485 also employs a proprietary control scheme that switches the device into a power save mode during light load, thereby extending the range of high efficiency operation. Therefore, ETA1485 is a much superior solution in comparison to other competitions in terms of efficiency and cost. Overall, ETA1485 is a highly efficient and robust solution for DC-DC step-down applications that requires wide input ranges. ETA1485 is available ESOP8 Packages.
APPLICATIONS
LCD TVs Notebook computers FPGA power supplies LED drivers
FEATURES
Wide Input Operating Range from 4.5V to 18V High Efficiency:
Up to 90%at Light Load Capable of Delivering 3A No External Schottky Diode Needed Current Mode control 0.923V Reference for Low Output voltages Logic Control Shutdown Thermal shutdown and UVLO Available in ESOP8 Package
ORDERING INFORMATION
PART PACKAGE TOP MARK PIN
ETA1485-E8A ESOP8
ETA1485 YLLFF
Date Code
Product Number
TYPICAL APPLICATION
10nF
VIN
2
IN
1
BST SW 3
100kΩ 22μF
7 EN
ETA1485
5
FB
8 SS
6
COMP
0.1μF GND
4
10μH VOUT 3.3V/3A
26.1kΩ
22μF X2
5.6kΩ 3.3nF
10kΩ
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ETA1485
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
BST 1 IN 2 SW 3
GND 4
ETA1485
ESOP8
8 SS 7 EN 6 COMP 5 FB
(Note: Exceeding these limits may damage the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability.)
IN Voltage...............................................................-0.3V to 20V SW, EN Voltage……………………………………..–0.3V to VIN+0.3V BST Voltage…………………………………………………–0.3V to SW+6V FB Voltage………………………………………………………….–0.3V to 6V SW to ground current ………….…….……….......Internally limited Operating Temperature Range ……................…–40°C to 85°C Storage Temperature Range ………………..….–55°C to 150°C
ELECTRICAL CHACRACTERISTICS
(VIN = 12V, unless otherwise specified. Typical values are at TA = 25oC.)
PARAMETER
CONDITIONS
Input Voltage Range
Input UVLO
Rising, Hysteresis=140mV
Input Supply Current Input Shutdown Current
VFB =1.0V
FB Feedback Voltage
FB Input Current
Error Amp Transconductance
Current Sense Transresistance
Switching Frequency
High side Switch On Resistance Low side Switch On Resistance High side Switch Current Limit
ISW =200mA ISW =200mA
SW Leakage Current EN Input Current
VIN=12V,VSW=0 or 12V, EN= GND
EN Input Low Voltage
Thermal Shutdown
Hysteresis=40°C
MIN TYP MAX UNITS
5 18 V
3.55 V
1 mA
6 μA
0.904 0.923 0.942
V
0.01 μA
800 μS
0.2
340 KHz
120 m
100 m
3.5 A
10 μA
1 μA
1 1.5 3 V
150 °C
PIN DESCRIPTION
PIN # NAME 1 BST 2 IN 3 SW 4 GND 5 FB 6 COMP 7 EN 8 SS
DESCRIPTION Bootstrap pin. Connect a 10nF capacitor from this pin to SW Supply Voltage. Bypass with a 22μF ceramic capacitor to GND Inductor Connection. Connect an inductor Between SW and the regulator output. Ground Feedback Input. Connect an external resistor divider from the output to FB and GND to set VOUT Regulator Compensation. Connect series RC network to GND. Enable pin for the IC. Drive this pin to high to enable the part, low to disable. Soft start pin. Connect a 0.1 uF capacitor from this pin to GND
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ETA1485
TYPICAL CHARACTERISTICS
(Typical values are at TA = 25OC unless otherwise specified.)
ŋ VOUT % Frequency (kHz)
100% Efficiency Vs IOUT
90%
80%
70%
60%
50%
40% 30% VON=12V
0.01 0.1 IOUT (A)
VOUT=5V VOUT=3.3V
1 10
1.01 VOUT Vs IOUT
Vin=12V
1.005
1
0.995 0.01 0.51 1.01 1.51 2.01 2.51 3.01 IOUT (A)
1.2 1.18 1.16 1.14 1.12 1.1 1.08 1.06 1.04 1.02
1 0
IQ Vs VIN
Iq (mA)
5 10 15 VIN (V)
20
3.3 3.29 3.28 3.27 3.26 3.25 3.24 3.23 3.22 3.21 3.2
4.5
VOUT Vs VIN
IOUT=0mA IOUT=300mA
9.5 14.5 VIN (V)
19.5
450 400 350 300 250 200 150 100 50
0 -40
Frequency Vs Temp
Vin=4.5V Vin=12V 0 40 80 Temperature (oC)
3A load Switching waveform Vin=12V, VOUT=5V
Start-up Waveform with Slow Vin
Start-up Waveform with Fast Vin
Load Transient Response
IQ (mA) VOUT (V)
VIN VOUT
ISW 100ms/div
VIN VOUT
ISW 100ms/div
VOUT
200mV/div
ISW
500mA/div
200s/div
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ETA1485
FUNCTIONAL DECRIPTIONS Loop Operation
The ETA1485 is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of delivering up to 3A of output current, integrated with a 110m synchronous.