Thermal Shutdown

Current Monitor

IMON

IMON

IMON

CS

V

K

R

V

=

´

´

(6)

CS

CSINT

IMON

IMON2

IMON

8

V

A

R

R

V

´

´

´

=

(7)

VID Table

TPS51513

The OCP values refer to the voltage between the current sense inputs. Refer to the parameter table to choose

Slewing section for details.

In OCP, the voltage droops until the UVP limit is reached. After the UPC limit is reached (approximately 80

µs

later) the converter sets PGOOD and PG signals inactive, performs the soft-stop sequence, and then latches

OFF. The converter remains in this state until the device is reset.

Negative Overcurrent Protection

The negative OCP circuit acts when the converter is sinking current. The converter continues to act in a “valley”

mode, so to have a similar negative DC limit, the absolute value of the negative OCP set point is typically 50%

higher than the positive one.

The TPS51513 has an internal temperature sensor. When the temperature reaches a nominal 160°C, the device

shuts down until the temperature cools approximately 10°C. Then, the converter latches off until either EN or

V5IN is cycled.

The TPS51513 includes a current monitor function. The current monitor puts out an analog voltage proportional

to the output power on the IMON pin. The equation is shown in Equation 6.

where

• K

• V

In order to increase the accuracy of the current monitor over temperature the IMON2 pin is provided to match the

temperature coefficients of two critical resistors in the circuit. Connect a resistor from IMON2 to VREF.

resistor can be calculated as shown in Equation 7.

where

• A

• 8 is the internal current mirror ratio

The IMON output requires a ceramic capacitor

≥3.3 nF connected to GSNS (or GND) for stable operation.

IMON Clamp Function

The IMON function also includes a clamp to prevent overvoltage of the device reading the IMON voltage. The

clamp voltage is set by the voltage applied at the IMONC pin (pin 12). IMONC is intended to be connected to the

same supply voltage as the downstream A/D converter, but other implementations are possible. To meet the

specified tolerances, a minimum headroom voltage for the IMON clamp must be observed. The V5FILT voltage

needs to be higher than the IMONC voltage by a minimum amount specified in the parameter table. Bypass

IMONC with a ceramic capacitor

≥0.1

µF connected to GND.

The TPS51513 belongs to a family of power management devicess that can be programmed to any eight VID

values. These values are from 0.3 V to 1.5 V in 12.5 mV steps. The specific VID selections for the TPS51513 are

given in Table 4. Other VID selections are possible, and are provided under a different device number. Contact

your TI field support team for details.

Copyright © 2009, Texas Instruments Incorporated

Submit Documentation Feedback

17

Product Folder Link(s) :TPS51513