ADP1055ACPZ-R7 datasheet(40/140 Pages) AD

40 / 140 page

ADP1055

Data Sheet

Rev. A | Page 40 of 140

Using the priority of faults (see the Priority of Faults section),

the fault that causes the ADP1055 to shut down is the one stored

in the FFID. For example, a configuration includes these faults:



OVP fault with a delay of 100 ms and five retry times



OCP fault with an action to shut down immediately with a

0 ms delay

If the OVP fault occurs and after the third retry attempt, the

OCP fault occurs, the OCP fault is stored in the FFID register.

On the other hand, if all five OVP retries occur before the OCP

fault occurs, the OVP fault is stored in the FFID. This statement

is true only if Register 0xFE_48[1:0] is set to 01. If it is set to 10,

the FFID is set to OVP on the first retry time.

Note that warning flags such as IOUT_OC_WARN and

VOUT_OV_WARN do not have debounce times.

The ADP1055 has a fault handler that can detect and track

faults and, in the case where a fault is programmed to shut

down and retry (restart) the system, the fault handler cycles the

ADP1055 through a shutdown and soft start procedure.

Throughout the soft start ramp, the fault handler continues to

monitor the device for any faults that can trigger a fault

response. Soft start blanking can be configured to ignore faults

during the soft start ramp.

If a fault condition triggers a shutdown-retry cycle, the fault

handler tracks the number of retry attempts of the programmed

fault response and permanently shuts down the device when the

configured number of retry times is reached. A shutdown-retry

cycle is considered successful if the triggering fault is cleared at

the end of the soft start ramp, at which point voltage regulation

is achieved. Following a successful retry attempt, the fault handler

removes the fault from its queue, clears all retry attempt counters,

and monitors the device for the next highest priority fault.

Debounce times can be added to a flag condition to effectively

delay the fault condition beyond the end of the soft start ramp.

Note that the fault handler considers this a successful retry

attempt (because no fault is seen when transitioning from soft

start to normal operation). The fault handler clears the fault and

resets the retry counters. For example, consider a TON_RISE

time of 10 ms, with a fault response set to shut down and retry

three times, and a flag condition that occurs during the soft

start ramp (t1 < 10 ms). If the debounce time (td) is small

enough such that t1 + td < TON_RISE, the fault condition is

latched before the end of the soft start ramp, and the ADP1055

shuts down and retries accordingly, while incrementing the

retry counter.

After three retries, the ADP1055 shuts down, requiring a

power-up to start again. However, if the debounce time (td) is

large enough such that t1 + td > TON_RISE, the fault condition

is latched after the ADP1055 transitions from soft start to

normal operation. In this scenario, the fault condition is cleared

and the retry counter is reset at the end of the soft start ramp.

The delayed fault initiates another set of three shutdown-retry

cycles. This behavior effectively causes the system to retry

indefinitely, even though the fault response is programmed to

retry only three times.

A notable exception is TON_MAX_FAULT when overshoot

protection is enabled. If the ADP1055 detects an out-of-

regulation condition for x consecutive switching cycles during

the soft start ramp (that is, the output voltage does not track the

desired ramp-up voltage), the ADP1055 tries to remedy the

situation by exiting soft start and retrying. As a result, the soft

start ramp ends prematurely, which has the effect of resetting

the retry counter.

Table 9 provides a summary of faults and respective debounce

times.

FAULT CONDITION DURING SOFT START AND

SOFT STOP

If a fault condition occurs during soft start, the controller responds

as programmed unless the flag is blanked. Flag blanking during

soft start and soft stop is programmed in Register 0xFE46 and

If a fault (for example, TON_MAX or IIN_OC) occurs at any

time during the soft start process with an action set to a value

other than shutdown, the remainder of the soft start ramp

continues at the transition rate specified by the PMBus

command VOUT_TRANSITION_RATE (Register 0x27).

During soft start, the TON_MAX fault is valid; after output

regulation is reached, the UVP fault is valid. This means that

the system does not start monitoring for UVP fault until after

the soft-start ramp-up.

WATCHDOG TIMER

In the case where the voltage fault response is set to disable the

outputs and wait for the faults to clear (Bits[7:6] = 11), the

ADP1055 disables the PWM outputs but does not immediately

shut down and restart through a soft start cycle. The ADP1055

keeps the PWM outputs disabled until the fault is cleared, after

which the PWM outputs are reenabled.

If the fault is not cleared, the system can potentially remain in a

dormant condition for an infinitely long time. To prevent this

condition, a watchdog timer can be set to time out the fault

condition. The WDT_SETTING command (Register 0xFE3F)

is used to set a timeout of 0 sec, 1 sec, 5 sec, or 10 sec, after

which the system shuts down, captures the FFID, and requires a

power-up (CTRL pin or OPERATION command) to restart.

ADP1055ACPZ-R7 датащи(PDF) 40 Page - Analog Devices

ADP1055ACPZ-R7 датащи(HTML) 40 Page - Analog Devices

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 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL