PM6652 datasheet(40/53 Pages) STMICROELECTRONICS

40 / 53 page

Device description

PM6652

40/53

Doc ID 16867 Rev 5

Figure 42.

Valley current limit detection

If the overload is not removed, the output capacitor keeps discharging until the UV fault is

detected.

In order to set the right valley current limit threshold, the PM6652 internal parameters and

also external component accuracy must be considered.

A complete computation of the valley current limit threshold worst case variation can be

found in

Equation 22.

Equation 22

The “key parameter” is the low-side MOSFET ON-resistance,

δR

DS,ON, which takes into

account the maximum ON-resistance value and its thermal drift. The other parameters, with

the exception of RILIM (typical accuracy 1%), are all internal parameters: δIILIM<0.5 µA is the

current reference variation and VOFFSET<4 mV is the current limit comparator offset.

8.10.7

SVCC undervoltage protection

The PM6652 can detect an SVCC undervoltage (threshold 3.9 V typ.). When this fault

occurs, the high-side MOSFET is turned off and the low-side MOSFET is turned on. The

device is turned on again if the SVCC voltage is higher than 4.4 V (typ.). This fault protection

is always active.

8.10.8

Thermal protection

If the device internal temperature is greater than 150 °C, the thermal shutdown is

performed. The internal discharge MOSFET is turned on until VOUT is lower than about 100

mV, then the low-side MOSFET is turned on.

A COREON or SVCC toggle is required to turn on again the device. This fault detection is

masked during VID transitions and, during soft-start, until the power good signal is released.

⎟

⎠

⎞

⎜

⎝

⎛ δ

⎟⎟⎠

⎞

⎜⎜⎝

⎛

⋅

⎟⎟⎠

⎞

⎜⎜⎝

⎛ δ

⎟⎟⎠

⎞

⎜⎜⎝

⎛ δ

ILIM

OFFSET

ILIIM

ILIM

VALL

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