ST1S14PHR STMicroelectronics, ST1S14PHR Datasheet
ST1S14PHR
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ST1S14PHR Summary of contents
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Features ■ output current ■ Operating input voltage from 5 ■ 850 kHz internally fixed switching frequency ■ Internal soft start ■ Power good open collector output ■ Current mode architecture ■ Embedded ...
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Contents Contents 1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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ST1S14 7.1.2 7.1.3 7.2 Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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Pin settings 1 Pin settings 1.1 Pin connection Figure 2. Pin connection (top view) 1.2 Pin description Table 1. Pin description N Pin 1 BOOT EN1 GND E.p. ...
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ST1S14 2 Electrical data 2.1 Maximum ratings Table 3. Absolute maximum ratings Symbol V Power supply input voltage IN V Enable 1 voltage EN1 V Enable 2 voltage EN2 PG Power good BOOT Bootstrap pin SW Switching node V Feedback ...
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Electrical characteristics 3 Electrical characteristics All the population tested at T specified. The specification is guaranteed from (-40 to +125) T characterization and statistical correlation. Table 6. Electrical characteristics Symbol Parameter Operating input V IN voltage range MOSFET on R ...
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Table 6. Electrical characteristics (continued) Symbol Parameter Inhibit V Enable 1 levels EN1 Enable 1 biasing I EN1 current V Enable 2 levels EN2 Enable 2 biasing I EN2 current Thermal shutdown Thermal shutdown T SHDWN temperature Thermal shutdown T ...
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Functional description 4 Functional description The ST1S14 is based on a “peak current mode”, constant frequency control consequence the intersection between the error amplifier output and the sensed inductor current generates the control signal to drive the power ...
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ST1S14 4.1 Power supply and voltage reference The internal regulator circuit consists of a start-up circuit, an internal voltage pre-regulator, the bandgap voltage reference and the bias block that provides current to all the blocks. The starter supplies the start-up ...
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Functional description Figure 5. soft start phases PHASE 1 VREF_OUT VFB SHORT During normal operation a new soft start cycle takes place in case of: ● HICCUP mode current protection ● thermal shutdown event ● UVLO event ● the device ...
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ST1S14 4.4 Error amplifier The voltage error amplifier is the core of the loop regulation transconductance operational amplifier whose non inverting input is connected to the internal voltage reference (1.222 V), while the inverting input (FB) is ...
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Additional features and limitations 5 Additional features and limitations 5.1 Maximum duty cycle The bootstrap circuitry charges cycle by cycle the external bootstrap capacitor to generate a voltage higher than V An internal linear regulator charges the C free wheeling ...
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ST1S14 5.2 Minimum output voltage over V The minimum regulated output voltage at a given input voltage is limited by the minimum conduction time of the power element, that is 90nsec typical for the ST1S14: Equation 1 which is plotted ...
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Closing the loop 6 Closing the loop Figure 9. Block diagram of the loop PWM control Current sense - - + + PWM comparator 14/ switch L C compensation network Doc ...
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ST1S14 6.1 G (s) Control to output transfer function CO The accurate control to output transfer function for a buck peak current mode converter can be written as: Equation where R represents the load resistance ...
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Closing the loop 6.2 Error amplifier compensation network The ST1S14 embeds (see network which is effective to stabilize the system in most of the application conditions Figure 10. Transconductance embedded error amplifier and C introduce a pole ...
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ST1S14 Equation 9 Equation 10 whereas the zero is defined as: Equation 11 The embedded compensation network is R considered negligible, so the singularities are: Equation 12 6.3 Voltage divider The contribution of a simple voltage divider is: Equation 13 ...
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Closing the loop A small signal capacitor in parallel to the upper resistor (see divider implements a leading network (f system phase margin: Equation 14 where: 6.4 Total loop gain In summary, the open loop gain can be expressed as: ...
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ST1S14 Figure 12. Module plot Figure 13. Phase plot The cut-off frequency and the phase margin are: Equation kHz = = 12V f 71 kHz = = 48V ...
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Application information 7 Application information 7.1 Component selection 7.1.1 Input capacitor The input capacitor must be able to support the maximum input operating voltage and the maximum RMS input current. Since step-down converters draw current from the input in pulses, ...
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ST1S14 Ceramic capacitors: If available for the required value and voltage rating, these capacitors usually have a higher RMS current rating for a given physical dimension (due to very low ESR). The drawback is the considerably high cost. Tantalum capacitors: ...
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Application information Equation 21 A list of some tantalum capacitor manufacturers is provided in selection. Table 9. Output capacitor selection Manufacturer Nippon Chemicon (2) Sanyo POSCAP AVX 1. see Chapter 6: Closing the loop 2. POSCAP capacitors have some characteristics ...
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ST1S14 7.2 Layout considerations The layout of switching DC-DC converters is very important to minimize noise and interference. Power-generating portions of the layout are the main cause of noise and so high switching current loop areas should be kept as ...
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Application information 7.3 Thermal considerations The dissipated power of the device is tied to three different sources: ● Conduction losses due to the not insignificant R Equation 24 Where D is the duty cycle of the application. Note that the ...
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ST1S14 Example: – – OUT – OUT R has a typical value of 0.2Ω °C and increases to a maximum value of 0.4Ω @ DS(on) 125 ...
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Application information The inductor current ripple during ON and OFF phases can be written as: ● ON phase Equation 29 ● OFF phase Equation 30 where V is the voltage drop across the diode, DCR D The pulse by pulse ...
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ST1S14 Equation 34 The Equation 29 Equation 35 considering T ON Equation 36 ( – Δ I --------------------------------------------------------------------- - TOFF where T =1 The voltage divider introduces a gain factor K between the ...
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Application information Figure 16. Minimum consequence for VIN > 12V the pulse by pulse current protection (in the worst case scenario which is minimum V peak current limitation over entire FB range 300mV < fact ...
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ST1S14 Whenever the current escalates, a second level current protection called “hiccup mode” is enabled. In case the hiccup current level (6.2A typical) is triggered the switching activity is prevented for 16ms and then a new soft start phase takes ...
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Application information The content given in Equation 40 The Figure 19 plots the (1.45A) given in Table 6: Electrical characteristics on page Equation 40 expresses the worst case scenario as it considers the minimum K gain of the voltage divider ...
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ST1S14 Figure 20. Short-circuit current V Figure 21 shows the operation of the constant current protection when a short circuit is applied at the output at the maximum input voltage. Accordingly to inductor current escalates over the foldback current limitation. ...
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... Nippon Chemicon (size 8 x 11.5 mm) NOT MOUNTED 4.7 KΩ (size 0603) 2.7 KΩ (size 0603) 47 KΩ (size 0603) 3A 60V STMicroelectronics (size SMB) 8.5μH =4.5A, I =4A Wurth SAT RMS ST1S14 PGOOD PGOOD TP7 TP7 ...
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ST1S14 Figure 23. PCB layout (component side) Figure 24. PCB layout (bottom side) Doc ID 17977 Rev 1 Application information 33/42 ...
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Typical characteristics 8 Typical characteristics Figure 25. Line regulation Figure 27 temperature (V DSon Figure 29 temperature SW 34/42 Figure 26. Load regulation = 12 V) Figure 28 Figure 30. Quiescent current vs ...
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ST1S14 Figure 31. Shutdown current vs temperature Figure 33. Efficiency vs I OUT Figure 35. Efficiency vs I OUT Figure 32. Duty cycle max vs temperature ( Figure 34 Figure 36 ...
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Typical characteristics Figure 37. Efficiency vs I OUT Figure 39 load transient (V Figure 41. Zoom - rising edge load transient ( 36/ Figure ...
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ST1S14 Figure 43. Zoom - rising edge load transient ( Figure 45 load transient (V Figure 47. Zoom - falling edge load ...
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Package mechanical data 9 Package mechanical data 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 ...
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ST1S14 Table 12. HSOP8 mechanical data Dim. Min ccc Figure 48. Package dimensions mm Typ. Max. 1.70 0.00 0.10 1.25 0.31 0.51 0.17 0.25 4.80 4.90 ...
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... Order code 10 Order code Table 13. Ordering information 40/42 Order code ST1S14PHR Doc ID 17977 Rev 1 ST1S14 Package HSOP8 - exposed pad ...
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ST1S14 11 Revision history Table 14. Document revision history Date 27-Oct-2010 Revision 1 Initial release Doc ID 17977 Rev 1 Revision history Changes 41/42 ...
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