EC3292A [E-CMOS]
2A, 18V, 500KHz, Synchronous StepDown DC/DC Converter;
| 型号： | EC3292A |
| 厂家： | 
E-CMOS Corporation |
| 描述： | 2A, 18V, 500KHz, Synchronous StepDown DC/DC Converter |
| 文件： | 总10页 (文件大小：293K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Features
General Description
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4.7V to 18V input voltage
The EC3292A is a high-frequency, synchronous,rectified, step-
down, switch-mode converter with internal power MOSFETs.
It offers a very compact solution to achieve a 2A continuous
output current over a wide input supply range, with excellent
load and line regulation.
Output adjustable from 0.8V to 15V
Output current up to 2A
Integrated 160mꢀ/85mꢀ power MOSFET switches
Shutdown current 3ꢁA typical
Efficiency up to 95%
The EC3292A has synchronous-mode Operation for higher
efficiency over the output current-load range. Current-mode
operation provides fast transient response and eases loop
stabilization.Protection features include over-current protection
and thermal shutdown.
Fixed frequency 500KHz
Internal soft start
Over current protection and Hiccup
Over temperature protection
RoHS Compliant and 100% Lead (Pb) Free
The EC3292A requires a minimal number of readily available,
standard external components and is available in space-saving
TSOT23-6L package.
Applications
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Distributed power systems
Networking systems
FPGA, DSP, ASIC power supplies
Notebook computers
Green electronics or appliance
Pin Assignments
Pins Description
TSOT23-6L
Symbol
Description
1
2
GND
SW
Ground.
Power switching output.
3
4
5
6
IN
FB
Power input.
Feedback input.
Enable input.
EN
BOOT
High-side gate drive boost input.
E-CMOS Corp. (www.ecmos.com.tw)
Page 1 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Application Information
Note: R5 and C7 are optional.
Details please see the DVT report.
Ordering Information
Part Number
Package
TSOT23-6
Marking
Marking Information
1. LLLLL：Lot No
3292A
LLLLL
EC3292ANT3R
E-CMOS Corp. (www.ecmos.com.tw)
Page 2 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Functional Block Diagram
Absolute Maximum Ratings
Supply Voltage VIN ……………………–0.3V to +20V
Switch Node VSW ……………… –0.3V to VIN+0.3V
Boost VBOOT ………………… VSW–0.3V to VSW+6V
All Other Pins ………………………… –0.3V to +6V
Junction Temperature ………………………+150°C
Lead Temperature ………………………… +260°C
Storage Temperature Range ……–65°C to +150°C
CAUTION: Stresses above those listed in “Absolute
Maximum Ratings” may cause permanent damage to
the device. This is a stress only rating and operation of
the device at these or any other conditions above those
indicated in the operational sections of this specification
is not implied.
Recommended Operating Conditions
Supply Voltage VIN ……...…………...…….…4.7V to 18V
Output Voltage VOUT ……...…………... 0.8V to VIN–3V
Operating Temperature Range ……...…–40°C to +125°C
Package Thermal Characteristics
TSOT23-6L:
Thermal Resistance, θJA ………………………100°C/W
Thermal Resistance, θJC ………………………… 55°C/W
E-CMOS Corp. (www.ecmos.com.tw)
Page 3 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Electrical Characteristics
(TA = +25°C, V IN = +12V, unless otherwise noted.)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Symbol
4.7
0.8
18
15
6
V
V
Supply Voltage
Output Voltage
VIN
VOUT
Shutdown Supply Current
Supply Current
3
µA
mA
V
VEN = 0V
0.09
VEN = 2.0V,VFB =0.85V
0.776 0.8
0.88
0.824
Feedback Voltage
VFB
4.7V ≤ VIN ≤ 18V
Feedback Over-voltage Threshold
V
1000
160
85
V/V
mꢀ
mꢀ
Error Amplifier Voltage Gain *
AEA
RDS(ON)1
RDS(ON)2
High-Side Switch-On Resistance *
Low-side Switch-On Resistance *
VEN = 0V, VSW = 0V,
TA = +125°C
High-Side Switch Leakage Current
10
µA
Upper Switch Current Limit
Lower Switch Current Limit
Minimum Duty Cycle
3
3.6
0
A
A
From Drain to Source
400
100
500
125
90
600
150
KHz
KHz
%
Oscillation Frequency
FOSC1
FOSC2
DMAX
Short Circuit Oscillation Frequency
Maximum Duty Cycle
VFB = 0V
VFB = 0.5V
Minimum On Time *
120
1.22
1.32
3.75
ns
V
EN Falling Threshold Voltage
EN Rising Threshold Voltage
Input Under Voltage Lockout Threshold
VEN Falling
VEN Rising
VIN Rising
V
V
Input Under Voltage Lockout Threshold
Hysteresis
200
mV
Soft-Start Period
1
ms
°C
Thermal Shutdown *
150
* Guaranteed by design, not tested.
E-CMOS Corp. (www.ecmos.com.tw)
Page 4 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Typical Characteristics
VIN = 12V, VO = 3.3V, L1 = 4.7ꢁH, C1 = 10ꢁF, C2 = 10ꢁF x 2, TA = +25°C, unless otherwise noted.
Start UP & Inrush Current 12V→3.3V (Load 1A)
Output Ripple (12V => 3.3V, Load=2A)
Output Ripple (12V => 3.3V, Load=0A)
Shut Down (Iout 1A→Shut down)
Output Ripple (12V => 3.3V, Load=1A)
Dynamic Load (Iload=0.2A_1.2A;Vout=3.3V)
E-CMOS Corp. (www.ecmos.com.tw)
Page 5 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Short Circuit Protection
Efficiency(L=4.7uA)
E-CMOS Corp. (www.ecmos.com.tw)
Page 6 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Application Information
Overview
Setting the Output Voltage
The EC3292A is a synchronous rectified, current-mode,
step-down regulator. It regulates input voltages from
4.7V to 18V down to an output voltage as low as
0.8V, and supplies up to 2A of load current.
The EC3292A uses current-mode control to regulate
the output voltage. The output voltage is measured
The external resistor divider sets output voltage. The
feedback resistor R1 also sets the feedback loop
bandwidth through the internal compensation capacitor.
(see the typical application circuit). Choose the R1 around
10KΩ,and R2 by
R2=R1/(Vout/0.8V-1)
at FB through
a
resistive
voltage divider and
Use T-type network for when Vout is low.
amplified through the internal transconductance error
amplifier.
The converter uses internal N-Channel MOSFET switches
to step-down the input voltage to the regulated output
voltage. Since the high side MOSFET requires a
gate voltage greater than the input voltage, a boost
capacitor connected between SW and BOOT is
needed to drive the high side gate. The boost capacitor
is charged from the internal 5V rail when SW is low.
When the EC3292A FB pin exceeds 10% of the
nominal regulation voltage of 0.8V, the over voltage
comparator is tripped forcing the high-side switch off.
Figure 1：T-type network
Table 1 lists the recommended T-type resistors value for
common output voltages.
Pins Description
BOOT: High-Side Gate Drive Boost Input. BOOT supplies
the drive for the high-side N-Channel MOSFET switch.
Connect a 0.1ꢁF or greater capacitor from SW to BOOT
to power the high side switch.
IN: Power Input. IN supplies the power to the IC, as well
as the step-down converter switches. Drive IN with a
4.7V to 18V power source. Bypass IN to GND with
a suitably large capacitor to eliminate noise on the input
to the IC.
Table 1: Resistor selection for common output voltages.
Inductor
SW: Power Switching Output. SW is the switching node
that supplies power to the output. Connect the output
LC filter from SW to the output load. Note that
a capacitor is required from SW to BOOT to power
the high-side switch.
The inductor is required to supply constant current to
the output load while being driven by the switched
input voltage. A larger value inductor will result in less
ripple current that will result in lower output ripple
voltage. However, the larger value inductor will have a
larger physical size, higher series resistance, and/or
lower saturation current. A good rule for determining
the inductance to use is to allow the peak-to-peak ripple
current in the inductor to be approximately 30% of the
maximum switch current limit. Also, make sure that the
GND: Ground.
FB: Feedback Input. FB senses the output voltage to
regulate that voltage. Drive FB with
a
resistive
voltage divider from the output voltage. The feedback
threshold is 0.8V.
EN: Enable Input. EN is a digital input that turns the
regulator on or off. Drive EN high to turn on
the regulator, drive it low to turn it off. Pull up with 100kꢀ
resistor for automatic startup.
E-CMOS Corp. (www.ecmos.com.tw)
Page 7 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
peak inductor current is below the maximum switch
be estimated by:
IC1 = ILOAD × [ (VOUT/VIN) × (1 − VOUT/VIN) ]1/2
current limit. The inductance value can be calculated by:
L = [ VOUT / (fS × ꢂIL) ] × (1 − VOUT/VIN)
The worst-case condition occurs at VIN = 2VOUT, where
IC1= ILOAD/2. For simplification, choose the input
capacitor whose RMS current rating greater than
half of the maximum load current.
Where VOUT is the output voltage, VIN is the input voltage,
fS is the switching frequency, and ꢂIL is the peak-to-peak
inductor ripple current.
The input capacitor can be electrolytic, tantalum or
ceramic. When using electrolytic or tantalum capacitors,
a small, high quality ceramic capacitor, i.e. 0.1ꢁF, should
be placed as close to the IC as possible. When
using ceramic capacitors, make sure that they have
enough capacitance to provide sufficient charge to
prevent excessive voltage ripple at input. The input
voltage ripple for low ESR capacitors can be estimated by:
ꢂVIN = [ ILOAD/(C1 × fS) ] × (VOUT/VIN) × (1 − VOUT/VIN)
Where C1 is the input capacitance value.
Choose an inductor that will not saturate under the
maximum
inductor
inductor
peak
current.
The
peak
current can be calculated by:
LP = ILOAD + [ VOUT / (2 × fS × L) ] × (1 − VOUT/VIN)
Where ILOAD is the load current.
I
The choice of which style inductor to use mainly
depends on the price vs. size requirements and any EMI
requirements.
Output Capacitor
The output capacitor is required to maintain the DC
output voltage. Ceramic, tantalum, or low ESR
electrolytic capacitors are recommended. Low ESR
capacitors are preferred to keep the output voltage
ripple low. The output voltage ripple can be estimated
by:
Optional Schottky Diode
During the transition between high-side switch and
low-side switch, the body diode of the low-side power
MOSFET conducts the inductor current. The forward
voltage of this body diode is high. An optional Schottky
diode may be paralleled between the SW pin and GND
pin to improve overall efficiency. Table 2 lists example
Schottky diodes and their Manufacturers.
ΔVOUT = [ VOUT/(fS × L) ] × (1 − VOUT/VIN)
× [ RESR + 1 / (8 × fS × C2) ]
Where C2 is the output capacitance value and RESR is the
equivalent series resistance (ESR) value of the output
capacitor.
In the case of ceramic capacitors, the impedance at the
switching frequency is dominated by the capacitance.
The output voltage ripple is mainly caused by
the capacitance. For simplification, the output voltage
ripple can be estimated by:
Table 2: Diode selection guide.
ΔVOUT = [ VOUT/(8xfS2 xLxC2)] × (1 − VOUT/VIN)
In the case of tantalum or electrolytic capacitors, the
ESR dominates the impedance at the switching
frequency. For simplification, the output ripple can be
approximated to:
Part
Number
Voltage and
Current Rating
Vendor
B130
SK13
30V, 1A
30V, 1A
30V, 1A
Diodes Inc.
Diodes Inc.
ΔVOUT = [ VOUT/(fS × L) ] × (1 − VOUT/VIN) × RESR
The characteristics of the output capacitor also affect
the stability of the regulation system. The EC3292A can
be optimized for a wide range of capacitance and
ESR values.
MBRS130
International Rectifier
Input Capacitor
The input current to the step-down converter is
discontinuous, therefore a capacitor is required to
supply the AC current to the step-down converter while
maintaining the DC input voltage. Use low ESR
capacitors for the best performance. Ceramic capacitors
are preferred, but tantalum or low-ESR electrolytic
capacitors may also suffice. Choose X5R or X7R
dielectrics when using ceramic capacitors.
External Bootstrap Diode
An external bootstrap diode may enhance the efficiency
of the regulator, the applicable conditions of external
BOOT diode are:
● VOUT = 5V or 3.3V; and
● Duty cycle is high: D = VOUT/VIN > 65%
In these cases, an external BOOT diode is recommended
from the output of the voltage regulator to BOOT pin, as
shown in Figure 2.
Since the input capacitor (C1) absorbs the input
switching current it requires an adequate ripple current
rating. The RMS current in the input capacitor can
E-CMOS Corp. (www.ecmos.com.tw)
Page 8 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
PCB Layout Guide
PCB layout is very important to achieve stable operation.
Please follow the guidelines below.
1) Keep the path of switching current short
and minimize the loop area formed by Input capacitor,
high-side MOSFET and low-side MOSFET.
2) Bypass ceramic capacitors are suggested to be
put close to the VIN Pin.
3) Ensure all feedback connections are short and direct.
Place the feedback resistors and compensation
components as close to the chip as possible.
4) Rout SW away from sensitive analog areas such
as FB.
5) Connect IN, SW, and especially GND respectively to a
large copper area to cool the chip to improve thermal
performance and long-term reliability.
Figure 2: Add optional external bootstrap diode to
enhance efficiency.
The recommended external BOOT diode is IN4148, and
the BOOT capacitor is 0.1 ~ 1ꢁF.
BOM of EC3292A
When VIN ≤ 6V, for the purpose of promote the
efficiency, it can add an externalSchottky diode
between IN and BOOT pins, as shown in Figure 2.
Please refer to the Typical Application Circuit.
When VIN ≤ 6V, for the purpose of promote the
Efficiency ,it can add an externalSchottky diode
between IN and BOOT pins, as shown in Figure 3.
Item
1
Reference
Part
10ꢁF
100nF
0.1ꢁF
100K
C1
C5
C7
R4
2
3
4
Table 3: BOM selection table I.
Figure 3: Add a Schottky diode to promote efficiency
when VIN ≤ 6V.
L1
R1
R2
C2
Vout = 5.0V
Vout = 3.3V
Vout = 2.5V
Vout = 1.8V
Vout = 1.2V
6.8ꢁH
4.7ꢁH
3.3ꢁH
2.2ꢁH
2.2ꢁH
40.2K
40.2K
40.2K
40.2K
20.5K
7.68K
13K
10ꢁF×2
10ꢁF×2
10ꢁF×2
10ꢁF×2
10ꢁF×2
19.1K
32.4K
41.2K
Table 4: BOM selection table II
E-CMOS Corp. (www.ecmos.com.tw)
Page 9 of 10
3L03N-Rev.P001
EC3292A
2A, 18V, 500KHz,
Synchronous StepDown DC/DC Converter
Package Information
TSOT23-6L
Dimensions in mm
Dimensions in Inch
Symbol
Min
Max
Min
Max
A
A1
B
0.700
0.000
1.600
0.350
2.650
2.820
0.900
0.100
1.700
0.500
2.950
3.020
0.028
0.000
0.063
0.014
0.104
0.111
0.035
0.004
0.067
0.020
0.116
0.119
b
C
D
e
0.950 BSC
0.037 BSC
H
L
0.080
0.300
0.200
0.600
0.003
0.012
0.008
0.024
E-CMOS Corp. (www.ecmos.com.tw)
Page 10 of 10
3L03N-Rev.P001
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