 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LTC4216CMS Datasheet(PDF) 11 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LTC4216CMS Datasheet(HTML) 11 Page - Linear Technology |
|
|
11 / 24 page  LTC4216 4216f 11 Analog Current Limiting In addition to an electronic circuit breaker, the LTC4216 has included a novel analog current limit (ACL) amplifier that does not require an external compensation capacitor at the GATE pin. The amplifier’s stability is compensated by the large gate input capacitance (CISS) of the external MOSFET used. These MOSFETs usually have CISS ≥ 1nF. However, if the MOSFET’s gate input capacitance (CISS) is too small for loop stability, then connect an external capacitor between the GATE pin and ground to increase the total gate capacitance to ≥ 1nF. As given by Equation (4), the MOSFET current, IACL, is limited to the analog current limit voltage, ΔVACL(TH), 40mV typical, across the sense resistor, RSENSE, connected between SENSEP and SENSEN pins. I V R ACL ACL TH SENSE = ∆ () (4) The ΔVACL(TH) threshold is 1.6 times higher than the ΔVCB(TH)threshold(25mVtypical)toprovideduallevelcur- rent sensing. When the ACL amplifier servos the MOSFET current at ΔVACL(TH) across the sense resistor, it exceeds ΔVCB(TH) threshold causing the FILTER pin to charge C3 with 60µA pull-up. If the condition persists long enough for C3 to reach the VFILT(TH) threshold (1.253V), GATE is pulled low and ⎯F⎯A⎯U⎯L⎯T latched low. If the voltage across the sense resistor is greater than ΔVACL(TH) during an overload condition, the ACL amplifier will servo GATE downwards in an attempt to control the MOSFET current. Since the GATE pin voltage overdrives the MOSFET in normal operation, the ACL amplifier needs time to discharge the GATE to the threshold of the MOSFET for gate regulation. For mild overload, the ACL amplifier can control the MOSFET current, but in the event of a severe overload, the MOSFET current may overshoot as the MOSFET has large GATE overdrive initially. The GATE is quickly discharged to ground followed by the ACL ampli- fier taking control. For applications that require very fast analog current limit recovery from the GATE undershoot as it discharges, connect a series resistor, RZ, with an external capacitor, CZ, at the GATE pin as shown in Figure 17. Soft-Start The LTC4216 features a soft-start function that controls the di/dt of the inrush current during power-up. As large output load capacitors are commonly used in low-voltage applications, the normal inrush can be large enough to glitch the load supply. With the soft-start function, the gate of the external MOSFET is allowed to turn on very gradually to control the inrush current flowing into the load capacitor without causing a supply glitch. With an external capacitor, C2, connected between the SS pin and ground, the GATE is servoed by the ACL amplifier to track the rate of SS ramp-up during power-up. There are two slopes in the SS ramp-up profile: 10µA current source pull-up for a normal ramp rate; and 1µA current source pull-up for a slower ramp rate. Both the SS ramp rates are given as follows: Normal SS Ramp Rate: dV dt A C SS NOM () = µ 10 2 (5) Slower SS Ramp Rate: dV dt A C SS SLOW () = µ 1 2 (6) Figure 6. Circuit Breaker Filter Response for Intermittent Overload APPLICATIO S I FOR ATIO OVERLOAD DUTY CYCLE, D (%) 0 20406080 100 1 0.1 0.01 4216 F06 t/C3(s/ µF) = 1.253/[(60 • D) – 2.4] |
Similar Part No. - LTC4216CMS |
|
Similar Description - LTC4216CMS |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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
