Download EcoSpeed DC-DC Converters Product Brochure

Product Overview
SEMTECH
POWER
MANAGEMENT
EcoSpeed® DC-DC Converters:
Best-in-Class Performance for Dynamic
Point-of-Load Applications
Unique buck converter platform provides ultra-fast transient response and
high efficiency across the entire load range.
Description
The EcoSpeed® converter platform incorporates Semtech’s
patented(1) adaptive on-time (AOT) control architecture to
deliver:
• Very high efficiency across the entire load range
• Ultra-fast transient response
• Easy-to-use, small and highly integrated DC-DC converters
This unique architecture offers the benefits of conventional
converter topologies with optimal tradeoffs for best-in-class
performance in next-generation dynamic point-of-load
applications.
These buck converters are inherently well suited to implement
a reduced frequency power-save (PSAVE) mode for up
to 95% peak efficiency in light load conditions, with the
option of ultrasonic PSAVE mode for applications requiring
no audible resonance during power save.
Semtech’s EcoSpeed converters minimize output capacitance,
eliminate the need for external compensation components
and enable the use of ceramic input/output capacitors to
provide a simple, space-saving and low-cost solution.
Key Features
• Patented adaptive on-time control architecture
- Ultra-fast transient response
- Pseudo-fixed switching frequency typically ±15%
accuracy
- Programmable switching frequency: 200kHz to 1MHz
- Very high efficiency across the entire load range
- No external compensation components required
- Up to 95% peak standby efficiency
• Power save (PSAVE) maximizes light load efficiency
• Wide input voltage range: 3V to 28V
• Output current range: 1A to 30A
• SmartDrive™ technology reduces EMI
• Low profile MLPQ and MLPD packages
VOUT = 0.50V to 5.25V,
IOUT up to 10A
BST
3 to 28V
VIN
VOUT
LX
5V
ILIM
VDD
SC417
FB
Can be VLDO
if VIN > 4.5V
VOUT Enable,
PSAVE Select
VLDO Enable
EN/PSV
PGOOD
VLDO
ENL
VLDO = 0.75V to 5.25V,
ILDO up to 150mA
FBL
TON
(1) U.S. Patent No. 7,714,547
VOUT
Power Good
PGND
AGND
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Converters Product Overview
EcoSpeed DC-DC Converter Product Portfolio
Orderable
Part#
Type
On-Chip
LDO?
VIN
Range
VDD
Range
VOUT Range
IOUT
PGOOD Enable
(max)
SC171
Regulator
No
3 - 5.5V
3 - 5.5V
0.75 to 95% VIN
1A
Yes
SC172
Regulator
No
3 - 5.5V
3 - 5.5V
0.75 to 95% VIN
2A
Yes
PSAVE
Package
Yes
Ultrasonic
MLPD-10 (3 x 3 x 1mm)
Yes
Ultrasonic
MLPD-10 (3 x 3 x 1mm)
SC173
Regulator
No
3 - 5.5V
3 - 5.5V
0.75 to 95% VIN
3A
Yes
Yes
Ultrasonic
MLPD-10 (3 x 3 x 1mm)
SC173A
Regulator
No
3 - 5.5V
3 - 5.5V
0.75 to 95% VIN
3A
Yes
Yes
Regular
MLPD-10 (3 x 3 x 1mm)
SC174
Regulator
No
3 - 5.5V
3 - 5.5V
0.75 to 95% VIN
4A
Yes
Yes
Ultrasonic
MLPD-10 (3 x 3 x 1mm)
SC401B
Regulator
Yes
3 - 17V
3 - 5.5V
0.6 to 5.5V
15A
Yes
Yes
Ultrasonic
MLPQ-32 (5 x 5 x 1mm)
SC402B
Regulator
Yes
3 - 28V
3 - 5.5V
0.6 to 5.5V
10A
Yes
Yes
Ultrasonic
MLPQ-32 (5 x 5 x 1mm)
SC403B
Regulator
Yes
3 - 28V
3 - 5.5V
0.6 to 5.5V
6A
Yes
Yes
Ultrasonic
MLPQ-32 (5 x 5 x 1mm)
SC410
Regulator
Yes
5.5V to 24V
n/a
0.75 to 7.5V
3A
Yes
Yes
Ultrasonic
MLPD-10 (3 x 3 x 1mm)
SC414
Regulator
Yes
3 - 28V
3 - 5.5V
0.75 to 5.5V
6A
Yes
Yes
Ultrasonic
MLPQ-28 (4 x 4 x 1mm)
MLPQ-32 (5 x 5 x 1.0mm)
SC417
Regulator
Yes
3 - 28V
4.5 - 5.5V
0.5 to 5.5V
10A
Yes
Yes
Ultrasonic
MLPQ-32 (5 x 5 x 1mm)
SC418
PWM
Controller
Yes
3 - 28V
3 - 5.5V
0.5 to 5.5V
30A*
Yes
Yes
Prog. Ultrasonic
or Regular
MLPQ-UT-20 (3 x 3 x 0.6mm)
SC419
PWM
Controller
No
3 - 28V
4.5 - 5.5V
0.5 to 5.5V
30A*
Yes
Yes
Prog. Ultrasonic
or Regular
MLPQ-UT-20 (3 x 3 x 0.6mm)
SC424
Regulator
Yes
3 - 28V
3 - 5.5V
0.75 to 5.5V
6A
Yes
Yes
Regular
MLPQ-28 (4 x 4 x 1mm)
SC427
Regulator
Yes
3 - 28V
4.5 - 5.5V
0.5 to 5.5V
10A
Yes
Yes
Regular
MLPQ-32 (5 x 5 x 1mm)
SC493
I2C
Controller
Yes
Prog. Ultrasonic
or Regular
MLPQ-UT-20 (3 x 3 x 0.6mm)
No
3 - 28V
3 - 5.5V
0.5 to 5.0V
30A*
Yes
* External FET drive
EcoSpeed DC-DC Converter Block Diagrams
Reference
Controller & Regulator
Reference
Control
Soft
Start
On-Time
Generator
Soft
Start
Gate Drive
Control
On-Time
Generator
Zero-Cross
Valley
Current Limit
Valley
Current Limit
Controller
Excellent Efficiency Even at Light Loads
Efficiency vs Load (SC417)
PSAVE Mode
100%
PWM Mode
VIN = 12V
FSW = 300kHz
95%
0.75V Vout
0.9V Vout
1.3V Vout
1.5V Vout
1.8V Vout
2.5V Vout
3.3V Vout
5V Vout
90%
EFF (%)
Gate Drive
Control
Zero-Cross
Regulator
High Efficiency
Control
85%
80%
75%
70%
0.1
1
IOUT (A)
10
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Converters Product Overview
Excellent Transient Response
Load Transient Response — Load Falling (SC174)
Load Transient Response — Load Rising (SC174)
Programmable Pseudo-Fixed Frequency
Semtech’s EcoSpeed converters offer a programmable frequency
from 200kHz to 1MHz, which is maintained with an accuracy
of typically ±15% – similar to many conventional fixed frequency
implementations.
SmartDrive™ Technology
SmartDrive technology is Semtech’s approach to implementing
the converter gate drive circuitry to reduce EMI. EMI is usually
a problem during the turn-on of the high-side FET in a buck
converter power stage. This is due to the reverse recovery
charge current, which results in a high spike from the body
diode of the low-side FET. To avoid this, all Semtech EcoSpeed
products incorporate a two-step, high-side FET turn-on
Switching Frequency (SC417)
500
Switching Frequency (kHz)
Many applications are sensitive to DC-DC converter frequency
and require a fixed frequency to ensure that inductor-radiated
EMI is in a known and acceptable band. Conventional current
mode and voltage mode conversion architectures have a fixed
frequency with an accuracy typically up to ±20%. Other topologies, including simple hysteretic, or the fast-responding constant
on-time mode, generally have frequencies that are unpredictable
with limited ability to control the extreme variations in frequency
due to input and output conditions.
Tightly Controlled Programmable Frequency
450
±15%
400
350
300
250
200
150
100
50
0
10
21
32
43
5
4
6
5
7
6
8
7
9
8
10
9
11
10
12
11
Load Current (A)
Frequency Programmable from 200kHz to 1MHz
SmartDrive™ Reduces EMI
scheme. The first step is a weak turn-on to allow the reverse
recovery current to pass through. The second step is a full
turn-on to quickly transition the inductor phase node to VIN
with minimal power loss. This approach reduces EMI, while
maintaining high efficiency.
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Converters Product Overview
PSAVE: Low Standby Power and Fast Wake-Up Response
Power efficiency in standby mode is increasingly important for
today’s “green” initiatives. However, most electronic products
also require fast “wake-up” capability, which demands fast
recovery from low-power standby to full-power operation. To solve
this problem, EcoSpeed DC-DC converters offer a power-save
(PSAVE) mode, which lowers the switching frequency to cater
to the light load requirement during standby. This improves
efficiency during light loads by reducing the switching losses
associated with the power FET gate charge. Since the EcoSpeed
architecture responds on a cycle-by-cycle basis, when the load
flips from light to full conditions, the converter can quickly exit
PSAVE mode providing fast wake-up response time.
Several EcoSpeed DC-DC converters also offer an ultrasonic
PSAVE (UPSAVE) feature, which ensures that the device
switching frequency stays above a 25kHz threshold to eliminate audible resonance.
Additionally, all EcoSpeed devices offer smart PSAVE, which is
designed to prevent the output voltage from floating higher
than 10% by turning on the low-side power FET and draining
any excess charge from COUT. This ensures that in light load
conditions the converter does not hit a false OVP.
How Do EcoSpeed Converters Compare to Conventional Architectures?
The EcoSpeed buck converter platform incorporates the best
of current mode, voltage mode and constant on-time control
topologies, with minimal tradeoffs. The key to these performance advantages is Semtech’s patent-pending adaptive
on-time control (AOT) architecture, which uses an advanced
control loop to dynamically adjust the on-time based on input
voltage and output voltage. This results in a pseudo-fixed
frequency operation and very predictable EMI, comparable to
existing voltage and current mode topologies and better than
constant on-time architectures. Unlike conventional voltage
and current mode control topologies, the AOT architecture
eliminates the need for external error amplifiers, simplifying
design and reducing component count. Additionally, Semtech’s
AOT architecture works with all capacitor chemistries for
design flexibility and optimized BOM costs.
EcoSpeed Architecture Provides Optimal Trade-Offs
Function
Current Mode
Control
Voltage Mode
Control
Constant On-Time
EcoSpeed®
Adaptive On-Time
Line Regulation
Excellent
Good
Excellent
Excellent
Load Regulation
Excellent
Moderate
Excellent
Excellent
External Compensation
Single Pole
Double Pole
None
None
Stable Operation with Wide Range
of Load Capacitance
Yes
No
No
Yes
Switching Frequency
Constant
Constant
Variable
Pseudo-Constant
Simple, Cost-Effective Architecture
No
No
Yes
Yes
Loop Response
Fast
Slow
Ultra-Fast
Ultra-Fast
COUT
Flexible
Somewhat Limited
Somewhat limited
Flexible
PSAVE
Not Inherent
Not Inherent
Inherent
Inherent
PCB Layout Sensitivity
Yes
No
Yes
Yes
Semtech, the Semtech logo and EcoSpeed are registered marks of Semtech Corporation and SmartDrive™ is a trademark of Semtech Corporation. Semtech reserves the right to make changes to, or discontinue
any products described in this document without further notice. I2C and the I2C bus are trademarks of NXP B.V. Semtech makes no warranty, representation or guarantee, express or implied, regarding the suitability
of its products for any particular purpose. ©2011 Semtech Corporation. All rights reserved. EcoSpeedPB-0411
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