 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
L6246 Datasheet(PDF) 7 Page - STMicroelectronics |
|
||||||||||||||||||||||||||||||
L6246 Datasheet(HTML) 7 Page - STMicroelectronics |
|
|
7 / 12 page  POWER SUPPLY MONITOR This circuit monitors the logic supply (5V) and the power supply (12V) and activates the power on reset output (POR) and the VCM PARK circuit. After both logic and power supply reach their nominal value a timing capacitor (T_CAP) has to be charge before the POR output change from low to high level. POR delay = C ⋅ V I where: C is the capacitor value connected at pin T_CAP V is delta voltage that capacitor have to be charged (2.3V) I is the costant current charging the capacitor (4 µA typ.) At the two input pins, +12 FILTER CAP and + 5 FILTER CAP, can be connected two capacitors for filtering the noise on the power supply, avoid- ing in this case undesired commutations of the POR signal because of some fast negative spikes on the line. BRAKE AND PARKING CIRCUITS The voice coil driver is switched into the parking condition through the VCM PARK input or when the POR signal is low. In such condition immedi- ately the output stage turns on the two lower DMOS of the power bridge to activate the BRAKE of the voice coil motor. After a delay generated by the capacitor at the BRAKE DELAY pin, only one of the two lower DMOS stays on while the opposite half bridge is tristated. BRAKE delay = C ⋅ V I where: C is the capacitor value connected at pin BRAKE DELAY V is delta voltage that capacitor have to be charged (3V) I is the costant current charging the capacitor (5 µA typ.) The parking voltage is then supplied by the PARKING circuit connected to the output that has been tristated. The value of such a voltage is set by connecting an external resistor between the RPARK pin and ground. Vr = Vbandgap ⋅ 104 Rpark where: Vr is the retract voltage for parking the heads Vbandgap is the internal bandgap reference voltage of 1.4V Rpark is value of the resistor connected at RPARK pin The parking circuit takes the power supply from the spindle driver through the VBEMF pin, so that in case of power fail the retract of the heads is possible using the rectified BEMF voltage coming from the spindle motor. CHARGE PUMP The charge pump circuit is used as a means of al- most doubling the power supply voltage (12V) in order to drive the upper DMOS of the power bridge. The energy stored in the in the capacitor con- nected at VCP pin is also used to drive the gate of the external N-MOSFET. GATE DRIVER This circuit provide the voltage driving the gate of the external isolation N-MOSFET, and it is con- trolled by the POR signal. THERMAL The thermal protection circuit has two threshold, the first if the pre shut down alarm that activates the THERMAL SD signal and the second is the shut down temperature that tristates the output stage when the junction temperature increases over this level. APPLICATION INFORMATION Example of calculation of the error amplifier com- pansation for the stability of the current control loop. As can be seen from the draw of the current control loop circuit of the next page, the voltage across the load is: #1 VL =ACPW ⋅ ACERR ⋅ (ACINP ⋅ VIN -ACENSE ⋅ Vsense) Vsense =Rs ⋅ IL VL =(ZL + Rs) ⋅ IL where AC... is the closed loop gain of Power, Er- ror, Sense and Input Amplifier. Changing in the #1 the transfer function between the load current and the VIN is: #2 IL VIN = ACPW ⋅ ACERR ⋅ ACINP ZL + RS + ACPW ⋅ ACERR ⋅ ACSENSE ⋅ RS L6246 7/12 |
Similar Part No. - L6246 |
|
Similar Description - L6246 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.NET |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
