LP2975IMMX-12 National Semiconductor, LP2975IMMX-12 Datasheet - Page 9

• Manufacturer Part Number: LP2975IMMX-12
• Description: IC DRIVER/CONTR MOSFET LDO 8MSOP
• Manufacturer: National Semiconductor
• Type: Positive Fixedr

Specifications of LP2975IMMX-12

• Number Of Outputs: 1
• Voltage - Output: 12V
• Current - Supply: 180µA
• Voltage - Input: 1.8 ~ 24 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LP2975IMMX-12

Reference Designs
Load Regulation
Load regulation is defined as the maximum change in output
voltage as the load current is varied. It is measured by
changing the load resistance and recording the minimum/
maximum output voltage. The measured change in output
voltage is divided by the nominal output voltage and ex-
pressed as a percentage. V
Line Regulation
Line regulation is defined as the maximum change in output
voltage as the input voltage is varied. It is measured by
changing the input voltage and recording the minimum/
maximum output voltage. The measured change in output
voltage is divided by the nominal output voltage and ex-
pressed as a percentage. I
Output Noise Voltage
Output noise voltage was measured by connecting a wide-
band AC voltmeter (HP 400E) directly across the output
capacitor. V
Transient Response
Transient response is defined as the change in output volt-
age which occurs after the load current is suddenly changed.
V
The load resistor is connected to the regulator output using a
switch so that the load current increases from 0 to 5A
abruptly. The change in output voltage is shown in the scope
photo below (the vertical scale is 200 mV/division and the
horizontal scale is 10 µs/division). The regulator nominal
output (5V) is located on the center line of the photo.
The output shows a maximum change of about −600 mV
compared to nominal. This is due to the relatively small
output capacitor chosen for this design. Increasing C
greatly improves transient response (see Designs #2 and
#3).
IN
= 5.6V for this test.
5 mA ≤ I
5.4V ≤ V
0 ≤ I
Transient Response for 0–5A Load Step
IN
L
≤ 5A: LOAD REGULATION = 0.135%
L
= 6V and I
IN
≤ 5A: LOAD REGULATION = 0.012%
≤ 10V: LINE REGULATION = 0.03%
NOISE = 75 µV (rms)
L
= 5A for this test.
L
IN
= 5A for this test.
= 5.6V for this test.
(Continued)
10003437
OUT
9
DESIGN #2: V
Application Circuits, Adjustable Voltage Regulator)
Components
C
C
C
R1 = 237 kΩ, 1%
R2 = NOT USED
R
Tie feedback pin to V
P-FET = NDT452P
Heatsink: Tab of N-FET is soldered down to 0.6 in
area on PC board.
Output Voltage Adjustment: For this application, a 3.3V part
is “trimmed” down to 3V by using a single external 237 kΩ
resistor at R1, which parallels the internal 39.9 kΩ resistor
(reducing the effective resistance to 34.2 kΩ).
Because the tempco of the external resistor will not match
the tempco of the internal resistor (which is typically 3000
ppm), this method of adjusting V
tor is only recommended in cases where the output voltage
is adjusted ≤ 10% away from the nominal value.
Performance Data
Dropout Voltage
Dropout voltage is defined as the minimum input-to-output
differential voltage required by the regulator to keep the
output in regulation. It is measured by reducing V
output voltage drops below the nominal value (the nominal
value is the output voltage measured with V
0.5A for this test.
Load Regulation
Load regulation is defined as the maximum change in output
voltage as the load current is varied. It is measured by
changing the load resistance and recording the minimum/
maximum output voltage. The measured change in output
voltage is divided by the nominal output voltage and ex-
pressed as a percentage. V
Line Regulation
Line regulation is defined as the maximum change in output
voltage as the input voltage is varied. It is measured by
changing the input voltage and recording the minimum/
maximum output voltage. The measured change in output
voltage is divided by the nominal output voltage and ex-
pressed as a percentage. I
Output Noise Voltage
Output noise voltage was measured by connecting a wide-
band AC voltmeter (HP 400E) directly across the output
capacitor. V
Transient Response
Transient response is defined as the change in output volt-
age which occurs after the load current is suddenly changed.
V
IN
IN
OUT
C
SC
= 470 pF
= 3.5V for this test.
= 68 µF Tantalum
= 0.1Ω
3.5V ≤ V
= 2 X 68 µF Tantalum
0 ≤ I
L
IN
≤ 0.5A: LOAD REGULATION = 0.034%
DROPOUT VOLTAGE = 141 mV
= 5V and I
IN
OUT
≤ 6V: LINE REGULATION = 0.017%
NOISE = 85 µV (rms)
= 3V
OUT
@
L
= 0.5A for this test.
L
0.5A (Refer to Typical
IN
= 0.5A for this test.
= 3.5V for this test.
OUT
by using a single resis-
IN
www.national.com
= 5V). I
IN
2
until the
copper
L
=