Electronic Components Datasheet Search |
|
ISL6341EVAL1Z Datasheet(PDF) 10 Page - Intersil Corporation |
|
ISL6341EVAL1Z Datasheet(HTML) 10 Page - Intersil Corporation |
10 / 17 page 10 FN6538.2 December 2, 2008 4ms during the sampling; that could discharge a pre-biased output. Therefore, to avoid that case, but still come close to disabling OCP, a resistor (>60k Ω) is recommended. Note that conditions during power-up may look different than normal operation. For example, during power-up in a 12V system, the IC starts operation just above 4V; if the supply ramp is slow, the soft-start ramp might be over well before 12V is reached. So with lower gate drive voltages, the rDS(ON) of the MOSFETs will be higher during power-up, effectively lowering the OCP trip. In addition, the ripple current will likely be different at lower input voltage. Another factor is the digital nature of the soft-start ramp. On each discrete voltage step, there is in effect a small load transient and a current spike to charge the output capacitors. The height of the current spike is not controlled; it is affected by the step size of the output, the value of the output capacitors, as well as the IC error amp compensation. So it is possible to trip the overcurrent with in-rush current, in addition to the normal load and ripple considerations. OCP is always enabled during soft-start, so there is protection starting up into a shorted load. Undervoltage Protection The output is protected against undervoltage conditions by monitoring the VOS pin. An external resistor divider (similar ratio to the one on the FB pin) makes the voltage equal the 0.8V internal reference under normal operation. If the output goes too low (25% below 0.8V = 0.6V nominal on VOS), the output will latch off, with UGATE and LGATE both forced low. This requires toggling VCC (power-down and up) to restart (toggling COMP/EN will NOT restart it). The UV protection is not enabled until the end of the soft-start ramp (as shown in Figure 2). Figure 7 shows a case where VOUT (and thus VOS) is pulled down to the 75% point; both gate drivers stop switching, and the VOUT is pulled low by the disturbance, as well as the load, at a rate determine by the conditions, and the output components. The ISL6341C version does not have UVP; it relies on the OCP for shorted loads. The PGOOD UV comparator is separate, and is still active. Overvoltage Protection The output is protected against overvoltage conditions by monitoring the VOS pin, similar to undervoltage. If the output goes too high (25% above 0.8V = 1.0V nominal on VOS), the output will latch off. As shown in Figure 8, UGATE will be forced low, but LGATE will be forced high (to try to pull-down the output) until the output drops to 1/2 of the normal voltage (50% of 0.8V = 0.4V nominal on VOS). The LGATE will then shut off, but will keep turning back on whenever the output goes too high again. Overvoltage latch-off requires toggling VCC (power-down and up) to restart (toggling COMP/EN will NOT restart it). The OV protection is not enabled until the rising VCC POR trip point is exceeded. The OV protection is active during soft-start at the fixed 25% above the final expected voltage. The OVP is not gated off by tripping OCP (but the UVP is gated off if OCP trips first). If the VOS pin is disconnected, a small bias current on-chip will force an overvoltage condition. FIGURE 7. UNDERVOLTAGE PROTECTION UGATE (24V/DIV) GND> VOUT (0.25V/DIV) LGATE (12V/DIV) GND> GND> 75% FIGURE 8. OVERVOLTAGE PROTECTION UGATE (24V/DIV) GND> VOUT (0.5V/DIV) LGATE (12V/DIV) GND> GND> 125% 50% ISL6341, ISL6341A, ISL6341B, ISL6341C |
Similar Part No. - ISL6341EVAL1Z |
|
Similar Description - ISL6341EVAL1Z |
|
|
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 |