LM5009EVAL National Semiconductor, LM5009EVAL Datasheet - Page 3

• Manufacturer Part Number: LM5009EVAL
• Description: BOARD EVALUATION LM5009
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM5009EVAL

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 10V
• Current - Output: 150mA
• Voltage - Input: 12 ~ 95V
• Regulator Topology: Buck
• Frequency - Switching: 240Hz
• Board Type: Fully Populated
• Utilized Ic / Part: LM5009
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -
• Lead Free Status / Rohs Status: Not Compliant

B) Intermediate Ripple Level Configuration: This configu-
ration generates more ripple at V
uration, but uses one less capacitor. If some ripple can be
R4 is chosen to generate
minimum ripple current in this circuit is 32 mAp-p at minimum
V
tion of the feedback resistors. C6's minimum value is calcu-
lated from:
where t
R2//R3 is the equivalent parallel value of the feedback resis-
tors. For this evaluation board t
ns, and R2//R3 = 1.875 kΩ, and C6 calculates to a minimum
D) Alternate Low Ripple Configuration: A low ripple output
can be obtained by connecting the load to V
of options B or C above. Since R4 degrades load regulation,
this alternative may be viable for applications where the load
IN
. C6 couples that ripple to the FB pin without the attenua-
ON(max)
is the maximum on-time (at minimum V
≥
25 mV at V
FIGURE 3. Intermediate Ripple Level Configuration Using C6 and R4
ON(max)
OUT1
than the above config-
OUT1
is approximately 3540
, knowing that the
OUT2
FIGURE 4. Minimum Cost Configuration
in the circuits
IN
), and
3
tolerated in the application, this configuration is slightly more
economical, and simpler. R4 and C6 are used instead of R6,
C7, and C8, as shown in Figure 3.
of 1900 pF. The resulting ripple at V
mVp-p to 140 mVp-p over the input voltage range with the
circuit in continuous conduction mode. The ripple amplitude
is higher if the load current is low enough to force the circuit
into discontinuous conduction mode.
C) Minimum Cost Configuration: This configuration is the
same as option B above, but without C6. Since 25 mVp-p are
required at the FB pin, R4 is chosen to generate 100 mvp-p
at V
cuit is 32 mAp-p at minimum V
3.3Ω is used for R4. The resulting ripple at V
≊
the application can accept this ripple level, this is the most
economical solution. The circuit is shown in Figure 4.
current is relatively constant. If this method is used, ensure
R4’s power rating is appropriate for the load current.
105 mVp-p to
OUT1
, knowing that the minimum ripple current in this cir-
≊
580 mVp-p over the input voltage range. If
20181109
20181107
IN
. To allow for tolerances,
OUT1
ranges from
OUT1
ranges from
www.national.com
≊
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