+

FB

REF

2.5V

SW

L

R3

R4

R5

VIN

LM25007

COUT

VOUT

LM25007

SNVS401C – JANUARY 2006 – REVISED FEBRUARY 2013

www.ti.com

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.

Figure 6. Low Ripple Output Configuration

8

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