ANALOG DEVICES LT8692S Monolithic Synchronous Step Down Regulator Instruction Manual

ANALOG DEVICES LT8692S Monolithic Synchronous Step-Down Regulator

Product Information

Specifications:

• Input Voltage: 6.2V – 42V
• Output Voltage VOUT1: 4.80V – 5.20V
• Output Voltage VOUT2: 3.17V – 3.43V
• Output Voltage VOUT3: 1.73V – 1.87V
• Output Voltage VOUT4: 1.15V – 1.25V
• Maximum Output Current IOUT1: 2A
• Maximum Output Current IOUT2: 1A
• Maximum Output Current IOUT3: 1A
• Maximum Output Current IOUT4: 1A
• Switching Frequency: 1.8MHz – 2.2MHz
• Channel 1 Efficiency: 90% – 92%
• Channel 2 Efficiency: 90%
• Channel 3 Efficiency: 87%
• Channel 4 Efficiency: 90%

Product Usage Instructions

Quick Start Procedure:

1. With power off, connect the input power supply to the board through VIN and GND terminals on the top layer.
2. Connect the loads to the terminals VOUT1 and GND, VOUT2 and GND, VOUT3 and GND, VOUT4 and GND on the board.
3. Adjust the input voltage and load currents within the operating range.
4. Observe the output voltage regulation, transient, ripple voltage, efficiency, and other parameters.

Measurement Equipment Setup:

Refer to Figure 1 for proper equipment setup.

Parts List:

FAQ:

• Q: Can the regulators be synchronized to an external clock input?
• A: Yes, all regulators can be synchronized to a common external clock input or internal oscillator of 2MHz.
• Q: Are the design files for this circuit board available?
• A: Yes, the design files for this circuit board are available.
• Q: Where can I find more information about the LT8692S?
• A: The LT8692S data sheet provides a complete description of the part, operation, and application information. It should be read in conjunction with the quick start guide for demo circuit EVAL-LT8692S-AZ.
• Q: What should I be careful of when measuring input or output voltage ripples?
• A: Care must be taken to avoid a long ground lead on the oscilloscope probe when measuring the input or output voltage ripples. Measure the input or output voltage ripple by touching the probe tip directly across the VIN or VOUT capacitor terminals.

DESCRIPTION

Demonstration circuit EVAL-LT8692S-AZ is an ultra-compact 4 rail power supply featuring the LT®8692S, a 42V quad monolithic synchronous step-down Silent Switcher®. The demo circuit is designed for 5V, 3.3V, 1.8V, and 1.2V outputs from a nominal 12V input. The 3.3V, 1.8V, and 1.2V converters are powered from the high voltage buck regulator with 5V output, which is powered from a wide range of 6.2V to 42V input. The current capability is 2A for channel 1 and 1A for the low voltage channels.

Internal soft-start, individual current limit, and independent enable for each channel simplify the complex design of quad-output power converters. All regulators can be synchronized to a common external clock input or internal oscillator of 2MHz.

The table below summarizes the performance of the demo board at room temperature. The circuit can be easily modified for different applications.

The LT8692S data sheet gives a complete description of the part, operation, and application information. The data sheet must be read in conjunction with this quick start guide for demo circuit EVAL-LT8692S-AZ.
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

A
Maximum Output Current IOUT2|  | 1| A
Maximum Output Current IOUT3|  | 1| A
Maximum Output Current IOUT4|  | 1| A
Switching Frequency|  | 1.8| 2| 2.2| MHz
Channel 1 Efficiency| VIN = 12V, VOUT = 5V, IOUT = 2A with Channels 2, 3, 4 Disabled| 90| %
Channel 2 Efficiency| VIN234 = 5V , VOUT = 3.3V , IOUT = 1A| 92| %
Channel 3 Efficiency| VIN234 = 5V , VOUT = 1.8V , IOUT = 1A| 90| %
Channel 4 Efficiency| VIN234 = 5V , VOUT = 1.2V , IOUT = 1A| 87| %

QUICK START PROCEDURE

Demo circuit EVAL-LT8692S-AZ is easy to set up to evaluate the performance of the LT8692S. Refer to Figure 1 for proper equipment setup and follow the procedure below.

1. With power off, connect the input power supply to the board through VIN and GND terminals on the top layer. Connect the loads to the terminals VOUT1 and GND, VOUT2 and GND, VOUT3 and GND, VOUT4 and GND on the board. The default positions of the Headers are given in Table 1.
   Table 1. Default Positions of the Headers** NAME| JUMPER| POSITION**
   ---|---|---
   EN/UVLO| JP1| ON
   EN3| JP2| RUN
   EN2| JP3| RUN
   EN1| JP4| RUN
   EN4| JP5| RUN
   VIN234| JP6| VOUT1
2. Turn on the power at the input (VEMI+, VEMI–). Increase voltage to 12V. Make sure that the input voltage is always within spec. Refer to the data sheet on the burst mode operation in light load and high VIN conditions.
3. Check for the proper output voltages. The output should be regulated at 5V (±4%), 3.3V (±4%), 1.8V (±4%), 1.2V (±4%). Do not overload unless a proper thermal cooling method such as air flow or heat sink is applied.
4. Once the proper output voltage is established, adjust the input voltage and load currents within the operating range and observe the output voltage regulation, transient, ripple voltage, efficiency, and other parameters. When measuring the input or output voltage ripples, 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 capacitor terminals.

Figure 1. Proper Measurement Equipment Setup

PARTS LIST

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

Required Circuit Components

C0805C475K8RACAUTO
9| 2| C10, C23| CAP., 10µF, X5R, 50V, 10%, 1206| TAIYO YUDEN, UMK316BBJ106KL-T
10| 1| C14| CAP., 4.7pF, C0G/NP0, 50V, ±0.25pF, 0603| MURATA, GRM1885C1H4R7CA01D
11| 3| C15, C18, C21| CAP., 47µF, X5R, 4V, 20%, 0603| MURATA, GRM188R60G476ME15D
12| 1| C17| CAP., 10pF, C0G, 50V, 5%, 0603| AVX, 06035A100JAT2A
13| 1| C20| CAP., 39pF, C0G, 50V, 5%, 0603| AVX, 06035A390JAT2A
14| 1| FB1| IND., 100Ω AT 100MHz, FERRITE BEAD, 25%, 2A, 40mΩ, 0603| TDK, MPZ1608Y101BTA00
15| 1| L1| IND., 2.2µH, PWR, SHIELDED, 20%, 7.8A, 22.1mΩ, 4.3mm × 4.3mm, XEL4030, AEC-Q200| COILCRAFT, XEL4030-222MEB
16| 1| L2| IND., 1.8µH, POWER SHIELDED, 20%, 2.9A, 24.1mΩ, 3.2mm × 3.5mm, AEC-Q200| COILCRAFT, XGL3520-182MEB
17| 1| L3| IND., 1.5µH, POWER SHIELDED, 20%, 3.1A, 19.8mΩ, 3.2mm × 3.5mm, AEC-Q200| COILCRAFT, XGL3520-152MEB
18| 1| L4| IND., 1.2µH, POWER SHIELDED, 20%, 3.5A, 15.8mΩ, 3.2mm × 3.5mm, AEC-Q200| COILCRAFT, XGL3520-122MEB
19| 1| L5| IND., 0.22µH, PWR, SHIELDED, 20%, 6.5A, 11.4mΩ, 1212BZ, IHLP-11 SERIES| VISHAY, IHLP1212BZERR22M11
20| 4| R1, R3, R11, R14| RES., 1M, 1%, 1/10W, 0603, AEC-Q200| NIC, NRC06F1004TRF
21| 1| R2| RES., 191k, 1%, 1/10W, 0603| VISHAY, CRCW0603191KFKEA
22| 1| R4| RES., 340k, 1%, 1/10W, 0603| VISHAY, CRCW0603340KFKEA
23| 1| R5| RES., 316k, 1%, 1/10W, 0603, AEC-Q200| NIC, NRC06F3163TRF
24| 1| R6| RES., 19.1k, 1%, 1/10W, 0603, AEC-Q200| PANASONIC, ERJ3EKF1912V
25| 9| R10, R21, R22, R26-R31| RES., 100k, 1%, 1/10W, 0603| STACKPOLE ELECTRONICS, INC., RMCF0603FG100K
26| 1| R12| RES., 806k, 1%, 1/10W, 0603, AEC-Q200| NIC, NRC06F8063TRF
27| 1| R13| RES., 499k, 1%, 1/10W, 0603, AEC-Q200| VISHAY, CRCW0603499KFKEA
28| 1| U1| IC, QUAD MONOLITHIC SYNCHRONOUS STEP DOWN REGULATOR, LQFN-20| ANALOG DEVICES, LT8692SIV#TRPBF

Additional Demo Board Circuit Components

Hardware: For Demo Board Only

1| 17| E1-E10, E14, E16, E17, E19-E22| TEST POINT, TURRET, 0.094″ MTG. HOLE, PCB 0.062″ THK| MILL-MAX, 2501-2-00-80-00-00-07-0
---|---|---|---|---
2| 6| JP1-JP6| CONN., HDR, MALE, 1×3, 2mm, VERT, ST, THT, NO SUBS. ALLOWED| WURTH ELEKTRONIK, 62000311121
3| 1| JP7| CONN., HDR, MALE, 2×4, 2mm, VERT, ST, THT| WURTH ELEKTRONIK, 62000821121
4| 4| MP1-MP4| STANDOFF, NYLON, SNAP-ON, 0.50″| KEYSTONE, 8833
5| 7| XJP1-XJP7| CONN., SHUNT, FEMALE, 2-POS, 2mm| WURTH ELEKTRONIK, 60800213421

SCHEMATIC DIAGRAM

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor any infringements of patents or other rights of third parties that may result from its use. Specifications are subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high-energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.

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