LM3678SD-1.2EV National Semiconductor, LM3678SD-1.2EV Datasheet - Page 3

• Manufacturer Part Number: LM3678SD-1.2EV
• Description: BOARD EVAL FOR LM3678SD-1.2
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3678SD-1.2EV

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 0.8V or 1.2V
• Current - Output: 1.5A
• Voltage - Input: 2.5 ~ 5.5V
• Regulator Topology: Buck
• Frequency - Switching: 3.3MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM3678
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

Powering the LM3678 for Bench
Measurements
When powering the LM3678 with a bench power supply, it is
recommended to place a 100µF tantalum capacitor across
the VIN and GND supply terminals of the bench power supply.
This capacitor will reduce the input spike caused by the power
supply and long power cables. The combination of the power
supply and inductance within the power cables produce a
large voltage spike that may damage the device. In addition,
consideration must be given to the enable pin of the device.
The enable should never be taken high, until minimum guar-
anteed operating voltage of 2.7V is reached. The enable pin
should also never exceed the input voltage.
Operating Information
The LM3678 evaluation board is set for the following default
positions:
Mid Layer 1
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Top Layer
3
•
•
•
Evaluation Board Layout
LM3678 is a four-layer board designed to maximize the per-
formance. Top layer consists of high-current path and bottom
layer for low-current and logic signals path. Inner layer 1 and
layer 2 are dedicated for PGND (power GND) and SGND
(analog and logic GND). For optimum performance, it is rec-
ommended to separate the PGND and SGND pins and join
them together at the start GND on the PCB.
V
Mode = H (PWM Mode), for Auto Mode, set Mode = Low
(move jumper to inner position).
EN pin is tied to V
OUT
= 1.2V, for 0.8V, set VSELECT pin to low via jumper
IN
Mid Layer 2
via a jumper
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