IR36021 datasheet(28/41 Pages) IRF

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IR36021

DIGITAL POL BUCK CONTROLLER with I2C AND PMBus

Interface

February 27, 2013 | Rev 3.5

Note that when EN is pulled low, the device ramps down

Vout. During this time OVP level is equal to the reference

voltage (which is ramping down) plus the selected

threshold (Table 15). When the soft‐stop is done, the level

is switched to fixed OVP level.

OVP is disabled whenever Vout is ramped down using I2C

or PMBus commands.

TABLE 14: OVP OPTIONS

OVP_when‐disabled setting

When active

IC disabled & IC enabled

Off

IC enabled

Figure 33: External bias caused OVP2, which shuts down both

loops (EN2=low), Low‐side MOSFET latched ON for loop2

Figure 34: External bias caused OVP2, which shuts down both

loops (EN2=low), MOSFET released when output<0.3V for loop2

Output Under‐voltage Protection (UVP)

The IR36021 detects an output under‐voltage condition

if the sensed voltage at the CPU is below the user‐

programmable UVP threshold (Table 15) or a fixed 248mV

as defined by the VID setting and with or without the load

line (Using the fixed or programmable threshold, and the

load line term is user selectable). Upon detecting an

output under‐voltage condition, the IR36021 responds in

the same manner as the OCP, according to the setting

selected in Table 16.

TABLE 15: OVP/UVP THRESHOLDS

Value

Threshold

150mV

200mV

250mV

325mV

350mV

375mV

400mV

500mV

Over‐current Protection (OCP)

The IR36021 provides a user defined output over‐current

protection limit up to a maximum value of 62A per phase

per loop. For example, with 2 phases, the OCP maximum

would be 62A*2 phases = 124A. To set the OCP current

threshold, the current handeling capability of the power

stages, the inductor and the input supply should be

considered.

The controller action in OCP is configurable as shown in

Table 16.

TABLE 16: OCP & UVP MODE SELECTION

OCP/UVP Behavior Mode

Per phase OCP Threshold (0 to 62A)

Shutdown immediately

(cycle power or enable to restart)

Hiccup 2X before Shutdown

Hiccup indefinitely

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