Datasheet - LDFM - 500 mA very low drop voltage regulator

Document overview

  • Manufacturer or author: STMICROELECTRONICS
  • PDF pages: 24

Technical content

Datasheet sections

  • 1 Block diagram
  • 2 Pin configuration
  • 3 Typical application
  • 4 Absolute maximum ratings
  • 5 Electrical characteristics
  • 6 Application information
  • 6.1 External capacitors
  • 6.1.1 Input capacitor
  • 6.1.2 Output capacitor
  • 6.2 Enable pin operation
  • 6.3 Power Good
  • 7 Typical performance characteristics
  • 8 Package information
  • 8.1 DFN6 (2x2) packing information
  • 8.2 DFN6 (3x3) package information
  • 8.3 DFN6 (3x3 mm) packing information
  • 9 Ordering information

Features

  • Input voltage from 2.5 to 16 V
  • Very low dropout voltage (300 mV max. at 500 mA load)
  • Low quiescent current (200 µA typ. @ 500 mA load)
  • Available in 1 % precision
  • 500 mA guaranteed output current
  • Wide range of output voltages available on request: adjustable from 0.8 V, fixed up to 12 V in 100 mV steps
  • Logic-controlled electronic shutdown
  • Power Good
  • Fast dynamic response to line and load changes
  • Internal current and thermal protection
  • Temperature range: - 40 °C to 125 °C

Applications

  • PCs and laptop computers
  • Battery-powered equipment
  • Industrial and medical equipment
  • Portable equipment

Description

The LDFM is a fast, very low drop linear regulator which operates from an input supply voltage in the range of 2.5 V to 16 V. It is available in fixed and adjustable output voltage versions, from 0.8 V to 12 V. The LDFM features 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. Current and thermal protection are provided. Maturity status link LDFM 500 mA very low drop voltage regulator LDFM Datasheet DS9220 - Rev 7 - August 2024 For further information contact your local STMicroelectronics sales office.

1 Block diagram

Figure 1. Block diagram (generic version)

2 Pin configuration

Figure 2. Pin connection (top view) Table 1. Pin description DFN6-2x2 and 3x3

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 Typical application

Figure 3. Adjustable version (PPAK and DFN6 packages only)

4 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

5 Electrical characteristics

TJ = 25 °C, VIN = VOUT(NOM) + 1 V ( For VOUT < 1.5 V; VIN = 2.5 V.), CIN = 1 µF, COUT = 2.2 µF, ILOAD = 10 mA, VEN = 2 V, unless otherwise specified. Table 4. Electrical characteristics for LDFM (fixed versions)

Electrical characteristics

Symbol Parameter Test conditions Min. Typ. Max. Unit TSHDN Thermal shutdown 170 Hysteresis 10 1. For VOUT < 1.5 V; VIN = 2.5 V. 2. 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 for output voltages below 1.5 V. TJ = 25 °C, VIN = VOUT(NOM) + 1 V( For VOUT < 1.5 V; VIN = 2.5 V.), CIN = 1 µF, COUT = 2.2 µF, ILOAD = 10 mA, VEN = 2 V, unless otherwise specified. Table 5. Electrical characteristics for LDFM (adjustable version)

Symbol Parameter Test conditions Min. Typ. Max. Unit PG Power Good output voltage low VISINK = 6 mA, open drain output 0.4 SVR Supply voltage rejection VIN = VOUT+1 V +/- 0.5 VRIPPLE Freq. = 120 Hz, VOUT = 0.8 V dB VIN = VOUT+1 V +/- 0.5 VRIPPLE Freq. = 10 kHz, VOUT = 0.8 V eN Output noise voltage Bw = 10 Hz to 100 kHz, ILOAD = 100 mA. COUT = 2.2 µF 50 µVRMS/ VOUT TSHDN Thermal shutdown 170 Hysteresis 10 1. For VOUT < 1.5 V; VIN = 2.5 V. 2. 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 for output voltages below 1.5 V. LDFM

6 Application information

6.1 External capacitors

The LDFM requires external capacitors for regulator stability. These capacitors must be selected to meet the requirements of minimum capacitance and equivalent series resistance (see and ). It is advisable to locate the input/output capacitors as close as possible to the relative pins.

6.1.1 Input capacitor

An input capacitor with a minimum value of 1 µF is required with the LDFM. This capacitor must be located a distance of not more than 0.5" from the input pin of the device and returned to a clean analog ground. Any good quality ceramic capacitors can be used for this capacitor.

6.1.2 Output capacitor

It is possible to use ceramic capacitors but the output capacitor must meet the requirements for minimum amount of capacitance and E.S.R. (equivalent series resistance) value. A minimum capacitance of 2.2 µF is a good choice to guarantee the stability of the regulator. However, other COUT values can be used according to and , 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. Also, capacitor tolerance and variation with temperature must be kept in consideration in order to assure the minimum amount of capacitance at all times.

6.2 Enable pin operation

The Enable pin can be used to turn OFF the regulator when pulled down, so drastically reducing the current consumption. When the enable feature is not used, this pin must be tied to VIN to keep the regulator output ON at all times. To assure proper operation, the signal source used to drive the Enable pin must be able to swing above and below the specified thresholds listed in the electrical characteristics section (VEN). The Enable pin must not be left floating because it is not internally pulled down/up.

6.3 Power Good

The LDFM features an open drain Power Good (PG) pin to sequence external supplies or loads and to provide fault detection. This function is active when enable is high. This pin requires an external resistor (RPG) to pull PG high when the output is within the PG tolerance window. Typical values for this resistor range from 10 kΩ to 100 kΩ. LDFM

Application information

7 Typical performance characteristics

CIN = COUT = 1 µF, VIN = VOUT +1 V, VEN to VIN, IOUT = 10 mA, unless otherwise specified. Figure 4. Output voltage vs temperature

5 V version, V IN = V

Figure 5. Output voltage vs temperature for adjustable Figure 6. Line regulation vs temperature Figure 7. Load regulation vs temperature Figure 8. Short-circuit current vs drop voltage Figure 9. Dropout voltage vs temperature

Figure 22. SVR vs frequency (VOUT = 5 V) Figure 23. SVR vs frequency (VOUT = VADJ) Figure 24. Stability plane adj (COUT, ESR) Figure 25. Stability plane 3.3 V (COUT, ESR)

3.3 V version, V IN = V EN ; CIN = 1 µF

8 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.

8.1 DFN6 (2x2) packing information

Figure 26. DFN6 (2 x 2 mm) reel outline Table 6. DFN6 (2 x 2 mm) tape and reel mechanical data

Package information

Dim. mm Min. Typ. Max. B0 2.4 K0 1.3 P0 4 P 4

8.2 DFN6 (3x3) package information

Figure 27. DFN6 (3x3) package outline

Table 7. DFN6 (3x3) mechanical data Figure 28. DFN6 (3x3) recommended footprint

8.3 DFN6 (3x3 mm) packing information

Figure 29. DFN6 (3x3) tape outline

Figure 30. DFN6 (3x3 mm) reel outline Table 8. DFN6 (3x3) tape and reel mechanical data

9 Ordering information

Table 9. Order code

Ordering information

Revision history

Table 10. Document revision history 28-Aug-2012 1 Initial release. Part numbers LDFM and LDFM50 have been unified under LDFM. Updated the Features and the Description in cover page. Cancelled Table1: Device summary. 6: Electrical characteristics for LDFM (adjustable version). Updated Section 9: "Ordering information". Updated Section 9: "Ordering information". Added unit ΔVOUT in Table 6. Updated Figure 6 and Figure 14.

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