LM25007MMX Datasheet, PDF (8/19 Pages) Texas Instruments – LM25007 42V, 0.5A Step-Down Switching Regulator

LM25007
SNVS401C – JANUARY 2006 – REVISED FEBRUARY 2013
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For applications where lower output voltage ripple is required the load can be connected directly to the low ESR
output capacitor, as shown in Figure 6. The series resistor (R5) will degrade the load regulation. Another
technique for enhancing the ripple voltage at the FB pin is to place a capacitor in parallel with the feedback
divider resistor R3. The addition of the capacitor reduces the attenuation of the ripple voltage from the feedback
divider.
High Voltage Bias Regulator (VCC)
The LM25007 contains an internal high voltage bias regulator. The input pin (Vin) can be connected directly to
line voltages from 9 to 42 Volts. To avoid supply voltage transients due to long lead inductances on the input pin
(VIN), it is always recommended to connect a low ESR ceramic chip capacitor (≊ 0.1µF) between VIN and RTN
pins located close to the LM25007. The regulator is internally current limited to 11mA. Upon power up, the
regulator is enabled and sources current into an external capacitor connected to the VCC pin. When the voltage
on the VCC pin reaches its UVLO level (6.3V), the controller output is enabled.
An external auxiliary supply voltage can be diode connected to the Vcc pin. If the auxiliary voltage is greater than
7 Volts the internal regulator will shutoff, thus reducing internal power dissipation. Do not exceed 14V at VCC.
See Figure 7.
V_IN
L
SW
LM25007
R3
FB
R4
REF
2.5V
R5
+
V_OUT
C_OUT
Figure 6. Low Ripple Output Configuration
8
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