ANALOG DEVICES DC2993A-A High Efficiency 2:1 Monolithic Switched Capacitor Divider Instruction Manual

ANALOG DEVICES DC2993A-A High Efficiency 2:1 Monolithic Switched

Capacitor Divider

Product Information

• Specifications
  • Input Voltage Range: 4.5V to 24V
  • Output Voltage: Fixed ratio of half the input voltage (VIN/2)
  • Maximum Output Current: 12A
  • Typical Efficiency: 96.6%
  • Peak Efficiency: 98.3%
  • Switching Frequency: 380kHz
• Description
  • The LTC7825 High Efficiency 2:1 Monolithic Switched Capacitor Divider (DC2993A-A) is a high efficiency, high density, open loop charge pump DC/DC converter.
  • This demo board serves as a voltage divider with an input voltage range of 4.5V to 24V.
  • The output voltage is a fixed ratio of half the input voltage (VIN/2) and can supply a load current of up to 12A.
  • The DC2993A-A provides a highly efficient solution of 96.6% at full load, running at a switching frequency of 380kHz.
  • For dual-phase operation, please refer to the DC2993A-B demo manual.
  • Design files for this circuit board are available.
  • All registered trademarks and trademarks are the property of their respective owners.

Product Usage Instructions

• Quick Start Procedure
  • The following steps outline the quick start procedure for setting up and evaluating the LTC7825 using demonstration circuit DC2993A-A:
  • With the power off, connect the input power supply to VIN (4.5V to 24V) and GND (input return).
  • Connect the output loads between VOUT and GND (initial load: no load).
  • Connect the DVMs to the input and output.
  • Check the default jumper/switch position: SW1 (RUN): OFF; JP1 (BIAS): OFF.
  • Turn on the input power supply and adjust the voltage to 20V.
  • ( Note: Ensure the input voltage does not exceed 24V.)
  • Turn on the switches: JP1: ON; SW1: ON.
  • Once the proper output voltage is established, adjust the loads within the operating range and measure the efficiency, output voltage ripple, and other parameters.
  • After completing all tests, adjust the load to 0A, turn off the switches: SW1 and JP1, and power off the input power supply.
• Notes
  • When performing the load step test with the onboard dynamic load circuit, ensure that the load step-up pulse duty cycle does not exceed 2% and the pulse duration is less than 500s to keep the temperature of the MOSFETs Q3 and Q4 in the dynamic load circuit within the safe region.
  • Instead of using the onboard dynamic load circuit, an electronic load can also be used for the load step test, which does not have the 2% maximum duty cycle limit for the load step.
• Frequently Asked Questions (FAQ)
  • Q: What is the input voltage range of the LTC7825?
  • A: The input voltage range of the LTC7825 is 4.5V to 24V.
  • Q: What is the maximum output current of the LTC7825?
  • A: The LTC7825 can supply a maximum output current of 12A.
  • Q: What is the typical efficiency of the LTC7825?
  • A: The typical efficiency of the LTC7825 is 96.6%.
  • Q: What is the switching frequency of the LTC7825?
  • A: The switching frequency of the LTC7825 is 380kHz.

DESCRIPTION

• Demonstration circuit DC2993A-A is a high efficiency, high density, open loop charge pump (inductors) DC/ DC converter.
• This demo board is a voltage divider whose input voltage range is 4.5V to 24V.
• The output voltage is a fixed ratio of half the input voltage (VIN/2) and can supply 12A of load current.
• The DC2993A-A provides a highly efficient solution of 96.6% at full load, running at 380kHz.
• This demo board features the LTC®7825, a fully integrated 24V/12A switched capacitor DC/DC converter with overvoltage and overcurrent protections in a 4mm × 5mm QFN package.
• Refer to the LTC7825 data sheet for more detailed information.
• The DC2993A-A requires no load start-up. Load current can be applied after VOUT is established.
• Refer to the “Voltage Divider Pre-Balance Before Switching” section in the LTC7825 data sheet for more details regarding the start-up of the voltage divider.
• The board offers an input disconnect MOSFET controlled by an LTC7825 OVG pin to provide overvoltage protection to the power stage when the VIN is higher than 24V.
• The board also features some protection functions, such as overcurrent and thermal shutdown, making it a reliable solution.
• For dual-phase operation, refer to the DC2993A-B demo manual.
• Design files for this circuit board are available.
• All registered trademarks and trademarks are the property of their respective owners.

PERFORMANCE SUMMARY

Specifications are at TA = 25°C

QUICK START PROCEDURE

Demonstration circuit DC2993A-A is easy to setup for evaluating the LTC7825. See Figure 1 for the proper measurement equipment setup and follow the procedure below.

1. With power off, connect the input power supply to VIN (4.5V to 24V) and GND (input return).
2. Connect the output loads between VOUT and GND (initial load: no load). See Figure 1.
3. Connect the DVMs to the input and output.
4. Check the default jumper/switch position: SW1 (RUN): OFF; JP1 (BIAS): OFF.
5. Turn on the input power supply and adjust the voltage to 20V.
   • NOTE: Make sure the input voltage does not exceed 24V.
6. Turn on the switches: JP1: ON; SW1: ON.
7. Check the proper output voltages from VO_SNS+ to VO_SNS–.
8. Once the proper output voltage is established, adjust the loads within the operating range and measure the efficiency, output voltage ripple, and other parameters.
9. After completing all tests, adjust the load to 0A, turn off the switches: SW1 and JP1, and power off the input power supply.

Notes

1. When measuring the output or input voltage ripple, do not use the long ground lead on the oscilloscope probe. See Figure 2 for the proper scope probe technique. Short, stiff leads need to be soldered to the (+) and (–) terminals of an output capacitor. The probe tip needs to touch the (+) lead.
2. When doing the load step test with the onboard dynamic load circuit, please make sure the load step-up pulse duty cycle does not exceed 2%, and the pulse duration is less than 500μs so that the temperature of the MOSFETs Q3 and Q4 in the dynamic load circuit stay in the safe region. Instead of using the onboard dynamic load circuit, an electronic load can also be used for the load step test, which does not have the 2% maximum duty cycle limit for the load step.
3. It is recommended to set the electronic load in CR (constant resistance) mode for the evaluation of the DC2993A-A board. Some electronic loads draw negative current in CC (constant current) mode when evaluating the output overcurrent protection feature of DC2993A-A, which can violate the absolute maximum voltage rating –0.3V for VOUT and VLOW pins.

NOTES:

• FOR ACCURATE EFFICIENCY MEASUREMENTS: MEASURE VIN ON C25 AND VOUT ON C33.
• IT IS RECOMMENDED TO SET THE ELECTRONIC LOAD IN CR (CONSTANT RESISTANCE) MODE (SEE NOTES SECTION).
• Figure 1. Proper Measurement Equipment Setup
• Figure 2. Measuring Output Voltage Ripple

TEST RESULTS

Figure 3. Efficiency vs Load Current at Various VIN, VOUT = VIN/2, fSW = 380kHz

Figure 4. Load Regulation for 12A Design at Various VIN, VOUT = VIN/2, fSW = 380kHz

Figure 5. Load Regulation for 12A Design at VIN = 20V, VOUT = 10V, fSW = 380kHz

Figure 6. Output Voltage Ripple VIN = 20V, VOUT = 10V, IOUT = 12A, fSW = 380kHz

Figure 7. 0A to 10A Load Step at VIN = 20V, VOUT = 10V, fSW = 380kHz

Figure 8. Thermal Performance VIN = 20V, VOUT = 10V, IOUT = 12A, TA = 23°C, No Airflow

PARTS LIST

ITEM| QTY| REFERENCE| PART DESCRIPTION| MANUFACTURER/PART NUMBER
---|---|---|---|---

Required Circuit Components

1| 1| C1| CAP., 4.7μF, X5R, 10V, 10%, 0402, NO SUBS. ALLOWED| TDK, C1005X5R1A475K050BC
---|---|---|---|---
2| 2| C2, C3| CAP., 68μF, ALUM POLY, 50V, 20%, SMD,

8.3mm × 8.3mm

| NICHICON, GYA1H680MCQ1GS
3| 19| C4-C21, C129| CAP., 2.2μF, X5R, 50V, 10%, 0603| TAIYO YUDEN, UMK107BBJ225KA-T MURATA, GRM188R61H225KE11D
4| 2| C22, C59| CAP., 2.2μF, X5R, 25V, 10%, 0402| MURATA, GRM155R61E225KE11D TDK C1005X5R1E225K050BC
5| 1| C23| CAP., 0.47μF, X5R, 50V, 10%, 0402| MURATA, GRM155R61H474KE11D TAIYO YUDEN UMK105ABJ474KV-F
6| 40| C24-C31, C33-C56, C60-C67| CAP., 10μF, X5R, 25V, 20%, 0603, NO SUBS. ALLOWED| MURATA, GRM188R61E106MA73D
7| 1| C32| CAP., 1μF, X5R, 25V, 10%, 0402| MURATA, GRM155R61E105KA12D/ GRM155R61E105KE11D SAMSUNG CL05A105KA5NQNC
8| 1| C57| CAP., 0.2pF, C0G, 50V, ±0.1pF, 0402| MURATA, GJM1555C1HR20BB01D
9| 1| C58| CAP., 0.1μF, X7R, 25V, 10%, 0402, NO SUBS ALLOWED| MURATA, GRM155R71E104KE14
10| 2| C121, C122| CAP., 2.2μF, X7R, 100V, 10%, 1210| TDK, C3225X7R2A225K230AB
11| 0| C123| CAP., OPTION 0603|
12| 2| C124, C125| CAP., 22μF, X5R, 25V, 10%, 1210| KEME, C1210C226K3PACTU
13| 1| C126| CAP., 0.047μF, X7R, 50V, 10%, 0603| AVX, 06035C473KAT2A
14| 1| C127| CAP., 220pF, X7R, 50V, 10%, 0603| AVX, 06035C221KAT2A
15| 1| C128| CAP., 1μF, X7R, 25V, 10%, 0603| MURATA, GRM188R71E105KA12D
16| 1| U1| IC, HIGH EFFICIENCY, 2:1 STEP-DOWN RATIO, SWITCHED CAPACITOR CONVERTER| ANALOG DEVICES, LTC7825AV#PBF
17| 1| U3| IC, SYNCHR. STEP-DOWN CONVERTER, MSOP-16 (MSE), 76V 500mA| ANALOG DEVICES, LTC3630AEMSE#PBF

Additional Demo Board Circuit Components

1| 0| R1, R5, R8| RES., OPTION 0402|
---|---|---|---|---
2| 0| R2, R9| RES., OPTION 0603|
3| 1| R3| RES., 10k, 0.1%, 1/16W, 0402| YAGEO, RT0402BRD0710KL
4| 1| R4| RES., 102k, 1%, 1/16W, 0402, AEC-Q200| STACKPOLE ELECTRONICS INC, RMCF0402FT102K
5| 1| R7| RES., 200k, 1%, 1/16W, 0402| NIC, NRC04F2003TRF
6| 2| R10, R29| RES., 0Ω, 1/10W, 0603, METAL STRIP AEC-Q200| VISHAY, WSL060300000ZEA9
7| 2| R21, R23| RES., 0Ω, 1/10W, 0603, AEC-Q200| VISHAY, CRCW06030000Z0EA
8| 1| R22| RES., 90.9k, 1%, 1/10W, 0603, AEC-Q200| VISHAY, CRCW060390K9FKEA
9| 1| R24| RES., 10k, 1%, 1/10W, 0603, AEC-Q200| PANASONIC, ERJ3EKF1002V
10| 1| R25| RES., 80.6k, 1%, 1/10W, 0603| VISHAY, CRCW060380K6FKEA
11| 1| R26| RES., 10k, 1%, 1/10W, 0603| VISHAY, CRCW060310K0FKEC
12| 2| R27, R28| RES., 0.2Ω, 1%, 1/2W, 2010, SENSEAEC-Q200| VISHAY, WSL2010R2000FEA
13| 1| STNCL1| TOOL STENCIL 700-DC2993A| ANALOG DEVICES, 830-DC2993A
14| 1| SW1| SWITCH, SLIDE, DPDT, 0.3A, 6VDC, PTH| C&K, JS202011CQN
15| 1| XJP1| CONN., SHUNT, FEMALE, 2-POS, 2mm| WURTH ELEKTRONIK, 60800213421
ITEM| QTY| REFERENCE| PART DESCRIPTION| MANUFACTURER/PART NUMBER
---|---|---|---|---

Hardware: For Demo Board Only

1| 8| E1- E6, E9, E10| TEST POINT, TURRET, 0.094″ MTG. HOLE, PCB 0.062″ THK| MILL-MAX, 2501-2-00-80-00-00-07-0
---|---|---|---|---
2| 4| J1-J4| EVAL BOARD STUD HARDWARE SET#10-32| ANALOG DEVICES, 720-0010
3| 2| J5, J6| CONN., RF, BNC, RCPT JACK, 5-PIN, STR, THT, 50Ω| AMPHENOL RF, 112404
4| 1| JP1| CONN., HDR, MALE, 1×3, 2mm, VERT, STR, THT, NO SUBS. ALLOWED| WURTH ELEKTRONIK , 62000311121
5| 1| L1| IND., 68μH, PWR SHIELDED, 20%, 0.74A, 0.42Ω, 2424LPS6225| COILCRAFT, LPS6225-683MRB
6| 1| LB1| LABEL SPEC DEMO BOARD SERIAL NUMBER| BRADY, THT-96-717-10
7| 4| MP1-MP4| STANDOFF, NYLON, SNAP-ON, 0.625″| KEYSTONE, 8834
8| 1| PCB1| PCBDC2993A| MAO BANG, 600-DC2993A
9| 1| Q1| XSTR., MOSFET, N-CH, 30V, 40A, PG-TSDSON-8 FL| INFINEON, BSZ0500NSI
10| 2| Q3, Q4| XSTR., MOSFET, N-CH, 40V, 14A, TO-252 (DPAK)| VISHAY, SUD50N04 -8M8P-4GE3

SCHEMATIC DIAGRAM

REVISION HISTORY

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LTC7825 High Efficiency 2:1 Monolithic Switched Capacitor Divider DEMO MANUAL DC2993A-A.

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