Datasheet - LDF - 1 A very low drop voltage regulator
Document overview
- Manufacturer or author: STMICROELECTRONICS
- PDF pages: 17
Technical content
Features
- Input voltage from 2.6 to 16 V
- Very low-dropout voltage (500 mV max. at 1 A load)
- Low quiescent current (200 μA typ. @ 1 A load)
- Available in 1% precision in DFN6 package
- 1 A guaranteed output current
- Wide range of output voltages available on request: adjustable from 0.8 V
- Logic-controlled electronic shutdown
- Power Good DFN package
- Fast dynamic response to line and load changes
- Internal current and thermal protections
- Temperature range: -40 °C to 125 °C
Applications
- Computer and laptop
- Battery-powered equipments
- Industrial and medical equipment
- Consumer and set-top box
Description
The LDF is a fast, very low drop linear regulator which operates from an input supply voltage in the range of 2.6 V to 16 V. It is available in adjustable output voltage versions, from 0.8 V to 12 V. The LDF features are: high output precision, very low-dropout voltage, low noise, and low quiescent current, therefore suitable for low voltage microprocessors and memory applications. Enable logic control pin and Power Good output are featured on DFN package. Current and thermal protection are provided. Maturity status link LDF
1 A very low drop voltage regulator
DS10028 - Rev 3 - October 2024 For further information contact your local STMicroelectronics sales office.
1 Block diagram
Figure 1. Block diagram
2 Pin configuration
Figure 2. Pin connection (top view) Table 1. DFN6-2x2 and 3x3 pin description
2 ADJ For adjustable versions: error amplifier input pin
6 VIN Input voltage
1 VOUT Output voltage
5 EN Enable pin logic input: low = shutdown, high = active
3 PG Power-good output
4 GND Ground
3 Absolute maximum ratings
Table 2. Absolute maximum ratings operation under these conditions is not implied. All values are referred to GND. Table 3. Thermal data
4 Electrical characteristics
TJ = 25 °C, VIN = VOUT(NOM) + 1 V, CIN = 1 μF, COUT = 2.2 μF, ILOAD = 10 mA, VEN = 2 V, unless otherwise specified. Table 4. LDF (adjustable version) electrical characteristics
0.8 V 55
- Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value. This
specification does not apply to output voltages below 1.6 V.
Electrical characteristics
5 Application information
5.1 External capacitors
The LDF voltage regulator requires external ceramic capacitors to assure the control loop stability. These capacitors must be selected to meet the requirements of minimum capacitance and equivalent series resistance (see Section 6: Typical characteristics and Section 6: Typical characteristics. Input/output capacitors should be located as closer as possible to the relative pins.
5.1.1 Input capacitor
An input capacitor, whose minimum value is 1 μF, must not be located farther than 0.5" from the input pin of the device and returned to a clean analog ground.
5.1.2 Output capacitor
Ceramic capacitors could be used on the output, provided that they must meet the minimum amount of capacitance to guarantee the stability of the regulator. Anyway, other COUT values can be used according to the Section 6: Typical characteristics and Section 6: Typical characteristics showing the allowable ESR range as a function of the output capacitance. The output capacitor must maintain its ESR in the stable region over the full operating temperature range to assure stability. Besides, capacitor tolerance and temperature variation must be taken into account to assure the minimum amount of capacitance.
5.2 Output voltage setting for ADJ version
In the adjustable version, the output voltage can be set from 0.8 V up to the input voltage minus the voltage drop across the pass transistor (dropout voltage), by connecting a resistor divider between the ADJ pin and the output, thus allowing remote voltage sensing. The resistor divider could be selected by the following equation: V OU T = V AD J 1 + R 1 R 2 , w it ℎ V AD J = 0.8 V Ty p . (1) It is recommended to use resistors with values in the range of 10 kΩ to 100 kΩ. Lower values can also be suitable, but current consumption increases.
5.3 Enable pin operation
This pin can be used to turn OFF the regulator when it is pulled down, so to drastically reduce the current consumption. When the enable feature is not used, this pin must be tied to VIN to keep the regulator output in ON state every time. To assure the proper operation, the signal source, used to drive the EN pin, must be able to swing above and below the specified thresholds listed in the electrical characteristics (VEN). The EN pin must not be left floating because it is not internally pulled down/up.
5.4 Power Good
The LDF features an open drain PG pin to sequence either external supplies or loads and to provide fault detection. This pin requires an external resistor (RPG) to pull Power Good high when the output is within the power-good tolerance window. Typical values for this resistor range from 10 kΩ to 100 kΩ. LDF
Application information
6 Typical characteristics
CIN = COUT = 1 μF, VIN = VOUT +1 V, VEN to VIN, IOUT = 10 mA, unless otherwise specified. Figure 3. Line regulation vs. temperature Figure 4. Load regulation vs. temperature Figure 5. Short-circuit current vs. dropout Figure 6. Dropout voltage vs. temperature Figure 7. Quiescent current vs. temperature, IOUT = 10 mA Figure 8. Quiescent current vs. temperature, IOUT = 1 A
7 Package information
To meet environmental requirements, ST offers these devices in different grades of ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions, and product status are available at: www.st.com. ECOPACK is an ST trademark.
7.1 DFN6 (3x3) package information
Figure 17. DFN6 (3x3) package outline
Package information
DS10028 - Rev 3 page 10/17
Table 5. DFN6 (3x3) mechanical data Figure 18. DFN6 (3x3) recommended footprint DS10028 - Rev 3 page 11/17
7.3 DFN6 (2x2x0,90) package information
Figure 19. DFN6 (2x2) package outline DS10028 - Rev 3 page 12/17
Table 6. DFN6 (2x2) mechanical data DS10028 - Rev 3 page 13/17
Figure 20. DFN6 (2x2) recommended footprint DS10028 - Rev 3 page 14/17
8 Ordering information
Table 7. Order code
Ordering information
DS10028 - Rev 3 page 15/17
Revision history
Table 8. Document revision history 05-Dec-2013 1 Initial release. Added Section 6.2: "Output voltage setting for ADJ version". 08-Oct-2024 3 Updated Table 7. Order code.
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