LP38693-Q1 datasheet(13/34 Pages) TI

13 / 34 page

LP38691, LP38693, LP38691-Q1, LP38693-Q1

www.ti.com

SNVS321N – JANUARY 2005 – REVISED MARCH 2015

8.3 Feature Description

8.3.1 Enable (EN)

The LP38693 has an Enable pin (EN) which allows an external control signal to turn the regulator output On and

Off. The Enable On/Off threshold has no hysteresis. The voltage signal must rise and fall cleanly, and promptly,

through the ON and OFF voltage thresholds. The EN pin voltage must be higher than the VEN(MIN) threshold to

ensure that the device is fully enabled under all operating conditions. The EN pin voltage must be lower than the

VEN(MAX) threshold to ensure that the device is fully disabled. The EN pin has no internal pullup or pulldown to

establish a default condition and, as a result, this pin must be terminated either actively or passively. If the EN

pin is driven from a source that actively pulls high and low, the drive voltage should not be allowed to go below

ground potential or higher than VIN. If the application does not require the Enable function, the pin should be

connected directly to the IN pin.

8.3.2 Thermal Overload Protection (TSD)

Thermal Shutdown disables the output when the junction temperature rises to approximately 160°C which allows

the device to cool. When the junction temperature cools to approximately 150°C, the output circuitry enables.

Based on power dissipation, thermal resistance, and ambient temperature, the thermal protection circuit may

cycle on and off. This thermal cycling limits the dissipation of the regulator and protects it from damage as a

result of overheating. The Thermal Shutdown circuitry of the LP38693 has been designed to protect against

temporary thermal overload conditions.

The Thermal Shutdown circuitry was not intended to replace proper heat-sinking. Continuously running the

LP38693 device into thermal shutdown degrades device reliability.

8.3.3 Foldback Current Limiting

Foldback current limiting is built into the LP38691 and LP38693 devices which reduces the amount of output

current the part can deliver as the output voltage is reduced. The amount of load current is dependent on the

differential voltage between the IN and OUT pins. Typically, when this differential voltage exceeds 5 V, the load

current will limit at about 350 mA. When the VIN – VOUT differential is reduced below 4 V, load current is limited to

about 850 mA.

8.4 Device Functional Modes

8.4.1 Enable (EN)

The EN pin voltage must be higher than the VEN(MIN) threshold to ensure that the device is fully enabled under all

operating conditions.

8.4.2 Minimum Operating Input Voltage (VIN)

The LP38691 and LP38693 do not include any dedicated UVLO circuitry. Neither device internal circuitry is fully

functional until VIN is at least 2.7 V. The output voltage is not regulated until VIN ≥ (VOUT + VDO), or 2.7 V,

whichever is higher.

Submit Documentation Feedback

Product Folder Links: LP38691 LP38693 LP38691-Q1 LP38693-Q1

LP38693-Q1 数据表(PDF) 13 Page - Texas Instruments

LP38693-Q1 数据表(HTML) 13 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

数据表下载