STEF033.fm
Document overview
- Manufacturer or author: STMICROELECTRONICS
- PDF pages: 25
Technical content
Datasheet sections
- 1 Device block diagram
- 2 Pin configuration
- 3 Maximum ratings
- 4 Electrical characteristics
- 5 Typical application
- 5.1 Operating modes
- 5.1.1 Turn-on
- 5.1.2 Normal operating condition
- 5.1.3 Output voltage clamp
- 5.1.4 Current limiting
- 5.1.5 Thermal shutdown and Auto-retry function
- 5.2 R Limit calculation
- 5.3 C dv/dt calculation
- 5.4 Enable-Fault pin
- 6 Typical performance characteristics
- 7 Package information
- 7.1 DFN10 (3x3 mm) package information
- 7.2 QFNxx/DFNxx (3x3 mm) packing information
- 7.3 Flip Chip 9 package information
- 8 Order codes
- 9 Revision history
Features
- Continuous current typ.: 3.6 A (DFN), 2.5 A (Flip Chip)
- N-channel on resistance (typ): 40 m Ω (DFN), 25 m Ω (Flip Chip)
- Enable/Fault functions
- Output clamp voltage (typ): 4.5 V
- Undervoltage lockout
- Short-circuit limit
- Overload current limit
- Controlled output voltage ramp
- Thermal latch (typ): 160 °C
- Uses tiny capacitors
- Latching and auto-retry versions
- Operative junction temp. - 40 °C to 125 °C
- Available in DFN10 3x3 and Flip Chip 9 bumps
Applications
- Hard disk drives
- Solid state drives (SSD)
- Hard disk and SSD arrays
- Computer
- DVD and Blu-Ray disc drivers
Description
The STEF033 is an integrated electronic fuse optimized for monitoring output current and the input voltage. Connected in series to the 3.3 V rail, it is able to protect the electronic circuitry on its output from overcurrent and overvoltage. The STEF033 has controlled delay and turn-on time. When an overload condition occurs, the device limits the output current to a predefined safe value. If the anomalous overload condition persists, it goes into an open state, disconnecting the load from the power supply. If a continuous short-circuit is present on the board, when the power is re-applied the eFuse initially limits the output current to a safe value and then goes again into the open state. The voltage clamping circuit prevents the output voltage from exceeding a fixed value, if the input voltage goes beyond this threshold. The device is equipped with a thermal protection circuit. Intervention of thermal protection is signaled to the board-monitoring circuits through an appropriate signal on the Fault pin. Unlike mechanical fuses, which must be physically replaced after a single event, the eFuse does not degrade in its performances following short-circuit/thermal protection intervention and is reset either by re-cycling the supply voltage or using the appropriate Enable pin. The STEF033 is also available in an auto-retry version; in case of thermal fault it automatically attempts to re- apply power to the load when the die temperature returns to a safe value. DFN10 (3 x 3 mm) Flip Chip 9
1 Device block diagram
Figure 1. STEF033 block diagram
2 Pin configuration
Figure 2. Pin configuration (top view) Table 1. Pin description
8 A2 En/Fault
cause a simultaneous shutdown during thermal events. turn-on. The internal capacitor allows a ramp-up time of around 1.4 ms. An external capacitor can be added to this pin to increase the ramp time. If an additional capacitor is not required, this pin should be left open. This feature is not available on the Flip Chip version.
10 A3 GND Ground pin
CC Exposed pad. Positive input voltage must be connected to V CC .
3 Maximum ratings
Note: Absolute maximum ratings are those values beyo nd which damage to the device may occur. Functional operation under these conditions is not implied. Table 2. Absolute maximum ratings
- The thermal limit is set above the maximum therma l rating. It is not recommended to operate the devi ce at
temperatures greater than the maximum ratings for e xtended periods of time. Table 3. Recommended operating conditions Table 4. Thermal data
Table 5. ESD performance
4 Electrical characteristics
Table 6. Electrical characteristics
3 Units
- Guaranteed by design, but not tested in productio n
Table 6. Electrical characteristics (continued)
5 Typical application
Figure 3. Application circuit, STEF033 and STEF033A (DFN10 package) Figure 4. Application circuit with Kelvin current sensing, STEF033J and STEF033JA
5.1 Operating modes
5.1.1 Turn-on
the internal control circuitry. value is around 1.6 ms (refer to Figure 5 , and Figure 15 ).
Typical application STEF033
5.1.2 Normal operating condition
The STEF033 eFuse behaves like a mechanical eFuse, buffering the circuitry on its output with the same voltage shown at its input, with a small voltage fall due to the N-channel MOSFET R DS(on) .
5.1.3 Output voltage clamp
This internal protection circuit clamps the output voltage to a maximum safe value, typically 4.5 V, if the input voltage exceeds this threshold.
5.1.4 Current limiting
When an overload event occurs, the current limiting circuit reduces the conductivity of the power MOSFET, in order to clamp the output current at the value selected externally by means of the limiting resistor R Limit ( Figure 3 ).
5.1.5 Thermal shutdown and Auto-retry function
If the device temperature exceeds the thermal latch threshold, typically 160 °C, the thermal shutdown circuitry turns the power MOSFET off, thus disconnecting the load. The EN/Fault pin of the device is automatically set to an intermediate voltage, in order to signal the overtemperature event. The STEF033 latch version can be reset from this condition either by cycling the supply voltage or by pulling down the EN pin below the V il threshold and then releasing it. On the STEF033A auto-retry version, the power MOSFET will remain in an OFF state until the die temperature drops below the hysteresis value. Once this happens, the internal auto- retry circuit attempts to reset the device, pulling up the EN/Fault pin to the operative value.
5.2 R Limit calculation
As shown in Figure 1 the device uses an internal N-channel Sense FET with a fixed ratio, to monitor the output current and limit it at the level set by the user. The R Limit value for achieving the requested current limitation can be estimated by using the “Current limit vs R Limit ”, graph in Figure 12 . The device has two levels of current limitation, depending on the load condition. The short-circuit current limit (I Short ) is the current level that is imposed when the output voltage decreases sharply, as in the case of a short-circuit on the output. The overload current limit (I Lim ), also described as “Current limit trip-point”, re presents the current level that is recognized by the device as an overload condition. Following this, the current limit trip point is reached the device enters into current limitation, and the current to the load is limited to the I Short value, which is generally lower than the trip-point value. The overload current limit (I Lim ) is dependent on the device reaction time, so it is influenced by the load current slew-rate. The faster the current increase, the higher the current limit trip point.
5.3 C dv/dt calculation
which the output voltage goes from 10% to 90% of the nominal voltage, is typically 1.4 ms. the C dv/dt pin can be selected using the following table. Figure 5. Delay time and V OUT rise time
5.4 Enable-Fault pin
same time, of providing information about the device status to the application. is pulled at low logic level, it will turn the output of the eFuse off. ON in normal operating conditions. This pin should never be biased to a voltage higher than 3.6 V. Table 7. Typical rise time values vs. dv/dt capacitor
application, in order to achieve a simultaneous enable/disable feature. by pulling down the Enable pin below the V il threshold and then releasing it. Figure 6. Enable/Fault pin status
6 Typical performance characteristics
Figure 7. Clamping voltage vs. temperature Figure 8. Short-circuit current vs. temperature Figure 9. Bias current vs. temperature (device Figure 10. Bias current vs. temperature (device Figure 11. ON-resistance vs. temperature Figure 12. Current limit vs. R Limit (IOUT ramp )
7 Package information
In order 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 DFN10 (3x3 mm) package information
Figure 23. DFN10 (3x3 mm) outline
Table 8. DFN10 (3x3 mm) mechanical data
Figure 24. DFN10 (3x3 mm) recommended footprint
7.2 QFNxx/DFNxx (3x3 mm) packing information
Figure 25. QFNxx/DFNxx (3x3 mm) tape and reel outline Table 9. QFNxx/DFNxx (3x3 mm) tape and reel mechanical data
7.3 Flip Chip 9 package information
Figure 26. Flip Chip 9 package outline
Figure 27. Flip Chip 9 recommended footprint (dimen sions in mm) Table 10. Flip Chip 9 mechanical data
8 Order codes
Table 11. Order codes
9 Revision history
Table 12. Document revision history 06-Aug-2013 1 Initial release. Section 7: Package information . 28-Jun-2020 3 Text minor changes. 24-Nov-2020 4 Updated Figure 9 and Figure 10 .