SGLS247B September 2011 – March 2016 TPS763-Q1
PRODUCTION DATA.
- 1 Features
- 2 Applications
- 3 Description
- 4 Revision History
- 5 Voltage Options
- 6 Pin Configuration and Functions
- 7 Specifications
- 8 Detailed Description
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
9.1 Application Information
The TPS763xx-Q1 low-dropout (LDO) regulators are new families of regulators which have been optimized for use in battery-operated equipment and feature low dropout voltages, low quiescent current (140 μA), and an enable input to reduce supply currents to less than 2 μA when the regulator is turned off.
The TPS763xx-Q1 uses a PMOS pass element to dramatically reduce both dropout voltage and supply current over more conventional PNP pass element LDO designs. The PMOS pass element is a voltage-controlled device that, unlike a PNP transistor, does not require increased drive current as output current increases. Supply current in the TPS763xx-Q1 is essentially constant from no-load to maximum load.
Current limiting and thermal protection prevent damage by excessive output current and/or power dissipation. The device switches into a constant-current mode at approximately 1 A; further load reduces the output voltage instead of increasing the output current. The thermal protection shuts the regulator off if the junction temperature rises above 165°C. Recovery is automatic when the junction temperature drops approximately 25°C below the high temperature trip point. The PMOS pass element includes a back diode that safely conducts reverse current when the input voltage level drops below the output voltage level.
A logic low on the enable input, EN shuts off the output and reduces the supply current to less than 2 μA. EN should be tied high in applications where the shutdown feature is not used.
9.2 Typical Application
A typical application circuit is shown in Figure 20.
NOTE:
TPS76316-Q1, TPS76318-Q1, TPS76325-Q1, TPS76301-Q1 TPS76333-Q1, TPS76350-Q1 (fixed-voltage options)9.2.1 Design Requirements
Table 2 lists the design requirements.
Table 2. Design Parameters
| PARAMETER | DESIGN REQUIREMENTS |
|---|---|
| Input voltage | 2.7 to 10 V |
| Output voltage | 2.5 to 6.45 V |
| Output current | 0 to 150 mA |
9.2.2 Detailed Design Procedure
9.2.2.1 External Capacitor Requirements
Although not required, a 0.047 μF or larger ceramic bypass input capacitor, connected between IN and GND and located close to the TPS763xx-Q1, is recommended to improve transient response and noise rejection. A higher-value electrolytic input capacitor may be necessary if large, fast-rise-time load transients are anticipated and the device is located several inches from the power source.
Like all low dropout regulators, the TPS763xx-Q1 requires an output capacitor connected between OUT and GND to stabilize the internal loop control. The minimum recommended capacitance value is 4.7 μF and the ESR (equivalent series resistance) must be between 0.3 Ω and 10 Ω. Capacitor values of 4.7 μF or larger are acceptable, provided the ESR is less than 10 Ω. Solid tantalum electrolytic, aluminum electrolytic, and multilayer ceramic capacitors are all suitable, provided they meet the requirements described above. Most of the commercially available 4.7-μF surface-mount solid tantalum capacitors, including devices from Sprague, Kemet, and Nichico, meet the ESR requirements stated above.
Table 3. Capacitor Selection
| PART NO. | MFR. | VALUE | MAX ESR | SIZE (H × L × W) |
|---|---|---|---|---|
| T494B475K016AS | KEMET | 4.7 μF | 1.5 Ω | 1.9 × 3.5 × 2.8 |
| 195D106x0016x2T | SPRAGUE | 10 μF | 1.5 Ω | 1.3 × 7.0 × 2.7 |
| 695D106x003562T | SPRAGUE | 10 μF | 1.3 Ω | 2.5 × 7.6 × 2.5 |
| TPSC475K035R0600 | AVX | 4.7 μF | 0.6 Ω | 2.6 × 6.0 × 3.2 |
9.2.2.2 Output Voltage Programming
The output voltage of the TPS76301-Q1 adjustable regulator is programmed using an external resistor divided as shown in figure 21. The output voltage is calculated using Equation 1.
where
- VREF = 1.192 V typical (the internal reference voltage)
- 0.995 is a constant used to center the load regulator (1%)
Resistors R1 and R2 should be chosen for approximately 7-μA divider current. Lower value resistors can be used, but offer no inherent advantage and waste more power. Higher values should be avoided as leakage currents at FB increase the output voltage error. The recommended design procedure is to choose R2 = 169 kΩ to set the divider current at 7 μA and then calculate R1 using Equation 2.
Figure 21. TPS76301-Q1 Adjustable LDO Regulator Programming
Table 4. Output Voltage Programming Guide
| OUTPUT VOLTAGE (V) | DIVIDER RESISTANCE (kΩ)(1) | |
|---|---|---|
| R1 | R2 | |
| 2.5 | 187 | 169 |
| 3.3 | 301 | 169 |
| 3.6 | 348 | 169 |
| 4 | 402 | 169 |
| 5 | 549 | 169 |
| 6.45 | 750 | 169 |
9.2.3 Application Curves
