Motore di ricerca datesheet componenti elettronici
  Italian  ▼
ALLDATASHEETIT.COM

X  

L6997D Scheda tecnica(PDF) 11 Page - STMicroelectronics

Il numero della parte L6997D
Spiegazioni elettronici  STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS
Download  23 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Produttore elettronici  STMICROELECTRONICS [STMicroelectronics]
Homepage  http://www.st.com
Logo STMICROELECTRONICS - STMicroelectronics

L6997D Scheda tecnica(HTML) 11 Page - STMicroelectronics

Back Button L6997D Datasheet HTML 7Page - STMicroelectronics L6997D Datasheet HTML 8Page - STMicroelectronics L6997D Datasheet HTML 9Page - STMicroelectronics L6997D Datasheet HTML 10Page - STMicroelectronics L6997D Datasheet HTML 11Page - STMicroelectronics L6997D Datasheet HTML 12Page - STMicroelectronics L6997D Datasheet HTML 13Page - STMicroelectronics L6997D Datasheet HTML 14Page - STMicroelectronics L6997D Datasheet HTML 15Page - STMicroelectronics Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 23 page
background image
11/23
L6997
1.6 Protection and fault
Sensing VSENSE pin voltage performs output protection. The nature of the fault (that is, latched OV or latched
UV) is given by the PGOOD and OVP pins. If the output voltage is between the 89% (typ.) and 110% (typ) of
the regulated value, PGOOD is high. If a hard overvoltage or an undervoltage occurs, the device is latched: low
side MOSFET and, high side MOSFET are turned off and PGOOD goes low. In case the system detects an
overvoltage the OVP pin goes high.
To recover the functionality the device must be shut down and restarted thought the SHDN pin, or the supply
has to be removed, and restart with the correct sequence.
These features are useful to protect against short-circuit (UV fault) as well as high side MOSFET short (OV
fault).
1.7 Drivers
The integrated high-current drivers allow using different size of power MOSFET, maintaining fast switching tran-
sition. The driver for the high side MOSFET uses the BOOT pin for supply and PHASE pin for return (floating
driver). The driver for the low side MOSFET uses the VDR pin for the supply and PGND pin for the return. The
main feature is the adaptive anti-cross-conduction protection, which prevents from both high side and low side
MOSFET to be on at the same time, avoiding a high current to flow from VIN to GND. When high side MOSFET
is turned off the voltage on the pin PHASE begins to fall; the low side MOSFET is turned on only when the volt-
age on PHASE pin reaches 250mV. When low side is turned off, high side remains off until LGATE pin voltage
reaches 500mV. This is important since the driver can work properly with a large range of external power MOS-
FETS.
The current necessary to switch the external MOSFETS flows through the device, and it is proportional to the
MOSFET gate charge and the switching frequency. So the power dissipation of the device is function of the ex-
ternal power MOSFET gate charge and switching frequency.
Eq 14
The maximum gate charge values for the low side and high side are given from:
Eq 15
Eq 16
Where fSW0 = 500Khz. The equations above are valid for TJ = 150°C. If the system temperature is lower the QG
can be higher.
For the Low Side driver the max output gate charge meets another limit due to the internal traces degradation;
in this case the maximum value is QMAXLS = 125nC.
The low side driver has been designed to have a low resistance pull-down transistor, around 0.5 ohms. This
prevents the voltage on LGATE pin raises during the fast rise-time of the pin PHASE, due to the Miller effect.
Because the driver voltage can be very low it should be considered also the ULTRA LOW VOLTAGE MOSFET.
This kind of MOSFET has very low threshold voltage, so the overdrive voltage can be enough to ensure correct
transition and low enough RDSON.
P
drive r
V
cc
Q
gTO T
F
SW
⋅⋅
=
Q
MAX H S
f
SW 0
f
SW
------------- 75n C
=
Q
MAX LS
f
SW0
f
SW
------------- 125 nC
=


Codice articolo simile - L6997D

Produttore elettroniciIl numero della parteScheda tecnicaSpiegazioni elettronici
logo
STMicroelectronics
L6997S STMICROELECTRONICS-L6997S Datasheet
515Kb / 30P
   STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS
L6997STR STMICROELECTRONICS-L6997STR Datasheet
515Kb / 30P
   STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS
More results

Descrizione simile - L6997D

Produttore elettroniciIl numero della parteScheda tecnicaSpiegazioni elettronici
logo
STMicroelectronics
L6997S STMICROELECTRONICS-L6997S Datasheet
515Kb / 30P
   STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS
logo
Sipex Corporation
SP6121CN-L SIPEX-SP6121CN-L Datasheet
1Mb / 42P
   Low Voltage, Synchronous Step Down PWM Controller
logo
Maxim Integrated Produc...
MAX1637 MAXIM-MAX1637 Datasheet
211Kb / 20P
   Miniature, Low-Voltage, Precision Step-Down Controller
19-1321; Rev 1; 2/98
logo
Texas Instruments
TPS53124 TI-TPS53124 Datasheet
719Kb / 22P
[Old version datasheet]   Dual Synchronous Step-Down Controller For Low-Voltage Power Rails
TPS53127 TI-TPS53127 Datasheet
482Kb / 23P
[Old version datasheet]   DUAL SYNCHRONOUS STEP-DOWN CONTROLLER FOR LOW VOLTAGE POWER RAILS
TPS53126 TI-TPS53126 Datasheet
979Kb / 30P
[Old version datasheet]   DUAL SYNCHRONOUS STEP-DOWN CONTROLLER FOR LOW VOLTAGE POWER RAILS
TPS53125 TI-TPS53125 Datasheet
462Kb / 22P
[Old version datasheet]   DUAL SYNCHRONOUS STEP-DOWN CONTROLLER FOR LOW VOLTAGE POWER RAILS
TPS53015 TI-TPS53015_15 Datasheet
855Kb / 22P
[Old version datasheet]   Single Synchronous Step-down Controller for Low Voltage Power Rails
TPS53114 TI-TPS53114 Datasheet
789Kb / 20P
[Old version datasheet]   SINGLE SYNCHRONOUS STEP-DOWN CONTROLLER FOR LOW VOLTAGE POWER RAILS
TPS53015 TI-TPS53015 Datasheet
864Kb / 21P
[Old version datasheet]   Single Synchronous Step-down Controller for Low Voltage Power Rails
More results


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


Scheda tecnica Scarica

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEETIT.COM
Lei ha avuto il aiuto da alldatasheet?  [ DONATE ] 

Di alldatasheet   |   Richest di pubblicita   |   contatti   |   Privacy Policy   |   scambio Link   |   Ricerca produttore
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
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