LT8609/LT8609A 42V, 2A Micropower Synchronous Step-Down Regulator Demonstration circuit 2195B is a 42V, 2A micropower
synchronous step-down regulator featuring the LT8609/ LT8609A.
There are two assembly versions. DC2195B-A is for the LT8609A and DC2195B-B is for the LT8609.
The difference is the LT8609A has slower edge speeds forimproved EMI at the expense of a small efficiency loss. The demo board is designed for 5V output from a 5.5V to 42V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The LT8609/LT8609A is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 2.5μA of quiescent current when output is regulated at 5V. Top and bottom power switches, compensationcomponents andothernecessary circuits are inside of the LT8609EMSE#TRPBF to minimize externalcomponents and simplify design.
The SYNC pin on the demo board is grounded by default for low ripple burst mode operation. Move JP1 to PULSE SKIPPINGposition can change the operation mode to pulse skipping operation. Once JP1 is on SPREAD SPECTRUM position, VCC is applied to theSYNCpin forlowEMI spread move JP1 to SYNC and apply the external clock to the SYNC turret. Figure 1 shows the efficiency of the circuit. The demo board has an EMI filter installed. Under spread spectrum operation, the radiated EMI performances of the board (with EMI filter) are shown in Figures 2 and 3. The red lines in Figures 2 and 3 are CISPR25 Class 5
peak limit. To use the EMI filter, the input should be tied to VEMI, not VIN. An inductor L2, which is a 0Ω jumper on the board by default now, can be added in the EMI filter to further reduce the conducted emission.
This board is suitable for a wide range of automotive, telecom, industrial, andothergeneralpurposeapplications.
TheLT8609/LT8609Adata sheetgives a completedescription ofthe part, operation and application information. The data sheet must be read in conjunction with this demo manual for DC2195B.
Feature
- Wide Input Voltage Range: 3.0V to 42V
- Ultralow Quiescent Current Burst Mode® Operation:
- <2.5µA IQ Regulating 12VIN to 3.3VOUT
- Output Ripple <10mVP-P
- High Efficiency 2MHz Synchronous Operation:
- >93% Efficiency at 1A, 5VOUT from 12VIN
- 3A Maximum Continuous Output
- Fast Minimum Switch-On Time: 45ns
- Adjustable and Synchronizable: 200kHz to 2.2MHz
- Spread Spectrum Frequency Modulation for Low EMI
- Allows Use of Small Inductors
- Low Dropout
- Peak Current Mode Operation
- Accurate 1V Enable Pin Threshold
- Internal Compensation
- Output Soft-Start and Tracking
- Small 10-Lead or 16-Lead MSOP Package
Applications
- GSM Transceivers
- General Purpose Step Down
- Low EMI Step Down
(Picture:Pinout / Diagram)
