IMON
CS
V
K
R
V
=
CS
CSINT
IMON
IMON2
IMON
8
V
A
R
V
=
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SLUS956A – JUNE 2009 – REVISED FEBRUARY 2010
The OCP values refer to the voltage between the current sense inputs. Refer to the parameter table to choose
the appropriate TRIPSEL value. The value of RSLEW changes depending on the termination. See the Voltage
Slewing section for details.
In OCP, the voltage droops until the UVP limit is reached. After the UPC limit is reached (approximately 80 ms
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.
Thermal Shutdown
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.
Current Monitor
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
KIMON is given in the parameter table
VCS is the differential voltage at the inputs to the current sense amplifiers
(6)
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.
After determining the full-scale voltage on the IMON output (VIMON) and selecting RIMON, the value of RIMON2
where
ACSINT is the gain of the internal current sense amplifier (given in the parameter table)
8 is the internal current mirror ratio
(7)
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
≥0.1mF connected to GND.
VID Table
The TPS51513 belongs to a family of power management devices 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 2009–2010, Texas Instruments Incorporated
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