ADP1052ACPZ-R7 datasheet(36/113 Pages) AD

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ADP1052

Data Sheet

Rev. B | Page 36 of 113

In the overvoltage detection block, there is an internal analog

comparator to detect the output voltage and generate the VOUT_

OV_FAULT flag when an overvoltage condition occurs. The over-

voltage reference voltage is set in Register 0x40. The debounce

time of the flag setting can be programmed for 0 μs, 1 μs, 2 μs, or

8 μs, using Register 0xFE26[7:6]. There is also a 40 ns propagation

delay, which is measured from the time when the OVP voltage

exceeds the threshold to the time when the comparator output

status is changed.

In the modulation flag triggering block, the real-time modulation

value is compared to the internal reference to generate the

LARGE_MODULATION flag. Register 0xFE6C[2] sets the

LARGE_MODULATION flag when the real-time modulation

value exceeds the modulation threshold set by Register 0xFE6B.

In the overvoltage responses block, there are two groups of over-

voltage protection responses: the VOUT_OV_FAULT_RESPONSE

PMBus command, set in Register 0x41, and the extended VOUT_

OV_FAULT_RESPONSE, set in Register 0xFE01[7:4].

There is a conditional OVP enable switch in Register 0xFE6C[0].

If the switch is cleared to 0, the conditional OVP function is

disabled and the OVP response always follows the VOUT_OV_

FAULT_RESPONSE PMBus command (Register 0x41).

If the switch is set to 1, the OVP response follows the

VOUT_OV_FAULT_RESPONSE command or the extended

VOUT_OV_FAULT_RESPONSE, depending on the status of

the LARGE_ MODULATION flag.

For example, when using a direct parallel system, if the VS+ pin

(Pin 2) and the VS− pin (Pin 1) in one power supply unit (PSU)

are shorted and this PSU experiences overvoltage failure, all the

PSUs detect the overvoltage signal. The LARGE_MODULATION

flag identifies the failed PSU. Typically, the failed PSU shuts down,

and the other PSUs continue to operate normally.

The modulation threshold is typically set with a value that is

slightly less than the modulation limit setting in Register 0xFE3C;

however, the modulation limit can change when the ADP1052

unit acts as a slave device to synchronize with an external clock

(see the Switching Frequency and Synchronization Registers

section for more information).

For more information about extended overvoltage protection,

see the Manufacturer Specific Protection Responses section and

the related register settings.

VOUT Undervoltage Protection (UVP)

The VOUT undervoltage protection feature follows PMBus specifi-

cations. The limits are programmed using the VOUT_UV_

FAULT_LIMIT command (Register 0x44), and the responses are

programmed in the VOUT_UV_FAULT_RESPONSE command

(Register 0x45). When the voltage reading in the READ_VOUT

command (Register 0x8B) falls below the VOUT_UV_FAULT_

LIMIT value, the VOUT_UV_FAULT flag in Register 0x7A[4]

is set.

During the period of the soft start ramp, the turn-on delay time

is specified by the TON_DELAY command (Register 0x60), and

the flag reenabled time is specified by Register 0xFE05[7:6]. The

VOUT_UV_FAULT flag is always blanked. Under these con-

ditions, an undervoltage condition never triggers the VOUT_

UV_FAULT flag.

IOUT Overcurrent Protection (OCP)

The IOUT overcurrent protection feature in the ADP1052 follows

PMBus specifications. The CS2 current sense information is used

for IOUT overcurrent protection. The limits are programmed in

the IOUT_OC_FAULT_LIMIT command (Register 0x46), and

the responses are programmed in the IOUT_OC_FAULT_

RESPONSE command (Register 0x47). The IOUT_OC_FAULT

flag in Register 0x78[4], Register 0x79[4], and Register 0x7B[7]

is set when the current reading in the READ_IIN command

exceeds the IOUT_OC_FAULT_LIMIT value.

When the IOUT overcurrent fault is triggered, the ADP1052 can

be programmed to enter constant current mode. Refer to the

Constant Current Mode section for more information.

OT_FAULT and OT_WARNING

The overtemperature protection feature in the ADP1052 follows

PMBus specifications. With the default setting, the OTP limit

is programmed using the OT_FAULT_LIMIT command in

OT_FAULT_RESPONSE command (Register 0x50).

There is an overtemperature warning flag, OT_WARNING,

in Register 0x7D[6]. The OT_WARNING limit is less than the

OT_FAULT_LIMIT, with an overtemperature hysteresis specified

by Register 0xFE2F[1:0].

When the temperature sensed at the RTD pin (Pin 23) exceeds the

OT_WARNING limit, the OT_WARNING flag (Register 0x7D[6])

is set. When the temperature sensed at RTD pin exceeds the

OT_FAULT_LIMIT, the OT_FAULT flag (Register 0x7D[7]) is set.

The OT_FAULT and OT_WARNING flags clear when the

temperature falls below the OT_WARNING limit (see Figure 39).

The OT_FAULT flag and the OT_WARNING flag can each be

separately set to trigger the PGOOD flag and drive the PG/ALT

pin (Pin 17) low.

TIME

OT_FAULT_LIMIT

OT_WARNING LIMIT

OT HYSTERESIS

OT_FAULT FLAG IS SET

OT_WARNING

FLAG IS SET

OT_FAULT AND OT_WARNING

FLAGS ARE CLEARED

OT_FAULT FLAG

OT_WARNING FLAG

Figure 39. OT Protection and OT Warning Operation

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