LINEAR TECHNOLOGY DC2110A Synchronous Micropower Step Down Regulator User Manual
- June 9, 2024
- LINEAR TECHNOLOGY
Table of Contents
LINEAR TECHNOLOGY DC2110A Synchronous Micropower Step Down Regulator
DESCRIPTION
Demonstration circuit 2110A is a monolithic step-down converter featuring LT®8631. The demo board is designed for 5V output from a 6.5V to 100V input at 400kHz switch-ing frequency. The wide input range makes it suitable for regulating power from a wide variety of sources, includ-ing automotive, industrial systems and telecom supplies. The LT8631 is a compact, high efficiency synchronous monolithic step-down switching regulator. The power switch, compensation and other necessary circuits are inside of the LT8631 to minimize external components and simplify design. The LT8631 switching frequency can be programmed either via oscillator resistor or external clock over a 100kHz to 1MHz range. The SYNC pin on the demo board is grounded (JP1 at Burst Mode® position) by default for low ripple Burst Mode operation. To synchronize to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret. If the pulse-skipping operation is required, move JP1 to fixed frequency position. Figure 1 shows the efficiency of the circuit at 12V input at the Burst Mode selection. The demo board has an EMI filter installed. The EMI per-formance of the board (with EMI filter) is shown in Figure 2. The red line in Figure 2 is CISPR25 Class 5 peak limit. The figure shows that the circuit passes the test with a wide margin. To achieve EMI/EMC performance as shown
the input EMI filter is required and the input voltage should be applied at VEMI turret pin, not VIN. The LT8631 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this demo manual for demo circuit 2110A. The LT8631 is assembled in a 20-lead TSSOP packages. Proper board layout is essential for maximum thermal and electrical performance. See the data sheet sections for details. Design files for this circuit board are available at http://www.linear.com/demo/DC2110A
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
SYMBOL| PARAMETER| CONDITIONS| MIN TYP
MAX| UNITS
---|---|---|---|---
VIN| Input Supply Range| | 6.5 100| V
VOUT| Output Voltage| | 4.88 5.04 5.2| V
fSW| Switching Frequency| RT = 25.5kΩ| 370 400 430| kHz
IOUT| Max Output Current| VIN = 12V| 1| A
EFE| Efficiency at DC| VIN = 12V, IOUT = 1A| 82.6| %
VIN = 12V, IOUT = 0.4A| 89.5| %
QUICK START PROCEDURE
Demonstration circuit 2110A is easy to set up to evalu-ate the performance of the LT8631. Refer to Figure 3 for proper measurement equipment setup and follow the procedure below:
NOTE. When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the VIN or VOUT and GND terminals. See Figure 4 for the proper scope technique.
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Place JP1 on GND position.
-
With power off, connect the input power supply to VEMI and GND. If the EMI/EMC performance is not important, the input EMI filter can be bypassed by connecting the input power supply to VIN and GND.
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With power off, connect loads from VOUT to GND.
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Turn on the power at the input.
Make sure that the input voltage does not exceed 100V. -
Check for the proper output voltages (VOUT = 5V). NOTE. If there is no output, temporarily disconnect the load to make sure that the load is not set too high or is shorted.
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Once the proper output voltage is established, adjust the load within the operating ranges and observe the output voltage regulation, ripple voltage, efficiency and other parameters.
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An external clock can be added to the SYNC terminal when SYNC function is used (JP1 on the SYNC posi-tion). Please ensure that the chosen RT sets the LT8631 switching frequency to 10% below the lowest SYNC frequency. See the data sheet Synchronization section for details.
PARTS LIST
| 1 | 1 | C1 | CAP, 0.1µF, X7R, 10V, 10% 0402 | TDK, C1005X7R1A104K |
|---|---|---|---|---|
| 2 | 1 | C5 | CAP, 2.2µF, X5R, 10V, 10% 0402 | TDK, C1005X5R1A225K050BC |
| 3 | 1 | C6 | CAP, 4.7pF, C0G, 50V, 0.25pF 0603 | MURATA, GRM1885C1H4R7CA01D |
| 4 | 1 | C7 | CAP, 47µF, X7R, 10V, 20% 1210 | MURATA, GRM32ER71A476KE15L |
| 5 | 1 | C8 | CAP, 0.1µF, X7R, 10V, 10% 0603 | AVX, 0603ZC104KAT2A |
| 6 | 1 | C4 | CAP, 1µF, X7R, 10V, 10% 0603 | SAMSUNG, CL10B105KP8NNNC |
| 7 | 1 | L1 | INDUCTOR, 22µH IHLP2525 | VISHAY, IHLP2525CZER220M11 |
| 8 | 1 | L2 | INDUCTOR, 2.2µH | COILCRAFT, XFL4020-222MEB |
| 9 | 1 | R1 | RES, 51.1k, 1/10W, 1% 0603 | VISHAY, CRCW060351K1FKEA |
| 10 | 2 | R2, R4 | RES, 1M, 1/10W, 1% 0603 | VISHAY, CRCW06031M00FKEA |
| 11 | 1 | R3 | RES, 25.5k, 1/10W, 1% 0603 | VISHAY, CRCW060325K5FKEA |
| 12 | 1 | R5 | RES, CHIP, 191k, 1/10W, 1% 0603 | VISHAY, CRCW0603191KFKEA |
| 13 | 1 | U1 | IC, BUCK REG FE-20(16) CB | LINEAR TECHNOLOGY, LT8631EFE#PBF |
Additional Demo Board Circuit Components
| 1 | 1 | C2 | CAP, ALUM, 10µF, 100V | SUN ELECTRONIC, 100CE10BS |
|---|---|---|---|---|
| 2 | 0 | C11 (OPT) | CAP, 0603 | |
| 3 | 0 | D1 (OPT) | SCHOTTKY BARRIER REC, POWER-DI-123 |
Hardware: For Demo Board Only
1| 10| E1 TO E10| TEST POINT, TURRET, 0.094″ MTG.HOLE| MILL-MAX,
2501-2-00-80-00-00-07-0
---|---|---|---|---
2| 1| JP1| 4 PIN 0.079 SINGLE ROW HEADER| SULLIN, NRPN041PAEN-RC
3| 1| XJP1| SHUNT, 0.079″ CENTER| SAMTEC, 2SN-BK-G
4| 0| R6 (OPT)| RES, 0603|
5| 4| MH1 TO MH4| STAND-OFF, NYLON 0.50″| KEYSTONE, 8833 (SNAP ON)
SCHEMATIC DIAGRAM
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under
the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear
Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION
PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO
BOARD herein may not be complete in terms of required design-, marketing-,
and/or manufacturing-related protective considerations, including but not
limited to product safety measures typically found in finished commercial
goods. As a prototype, this product does not fall within the scope of the
European Union directive on electromagnetic compatibility and therefore may or
may not meet the technical requirements of the directive, or other
regulations.
If this evaluation kit does not meet the specifications recited in the DEMO
BOARD manual the kit may be returned within 30 days from the date of delivery
for a full refund.
THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER
AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY,
INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR
PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE
TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling
of the goods.
Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer.
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