LGA-THSK-KIT-045 EMERSON-NETWORKPOWER [Emerson Network Power], LGA-THSK-KIT-045 Datasheet - Page 7

• Manufacturer Part Number: LGA-THSK-KIT-045
• Description: Embedded Power Device
• Manufacturer: EMERSON-NETWORKPOWER [Emerson Network Power]

Technical Reference Note
Applications (cont'd)
Output Capacitance
The LGA C Series has output capacitors inside the converter. Limited output capacitance, 10uF for the
3 A/6A/10A and 50 uF for the 20A, is required for stable operation. When powering loads with large
dynamic current requirements, improved voltage regulation is obtained by inserting low ESR capacitors
as close as possible to the load. Low ESR ceramic capacitors will handle the short duration high
frequency components of the dynamic current requirement. In addition, higher values of electrolytic
capacitors should be used to handle the mid-frequency components.
It is equally important to use good design practices when configuring the dc distribution system. Low
resistance and low inductance PCB layout traces should be utilized, particularly in the high current output
section. Remember that the capacitance of the distribution system and the associated ESR are within the
feedback loop of the power capabilities, thus affecting the stability and dynamic response of the module.
Note that the maximum rated value of output capacitance varies between models and for each output
voltage setpoint. A stability vs. Load Capacitance calculator, (see your sales representative), details how
an external load capacitance influences the gain and phase margins of the LGA C Series modules.
Setting Margin Control
To margin the output voltage up, pull the margin control pin high. To margin down, pull the margin
control pin low. If the pin is left floating, the feature is disabled. The maximum margining range is ±33%
of the output voltage setting, with maximum output at 5.5 V. The equations for margining up and down
are as follows:
Note: The margin control pin cannot be pulled in the following range:
See Table 1 for suggested margining values.
V margin_up = 0.1182 * R margin * R trim + 2k
V margin_down = 0.1182 * R margin * R trim + 2k
If, Vin ≤ 5V then V margin (max) = Vin
If, Vin > 5V then V margin (max) = 5V
R ofs+
R ofs-
R trim
R trim
Embedded Power for
Business-Critical Continuity
Rev. 12.07.09
LGA C Series
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