LM5035CMHSLASHNOPB datasheet(28/43 Pages) TI2

28 / 43 page

1.25V x (R1 + RCOMBINED)

OVPoff

R3 =

RCOMBINED =

1.25V x R1

UVLOoff ± 1.25V

R1 =

UVLOon - UVLOoff

23 PA

UVLO

LM5035C

VPWR

STANDBY

OFF

STANDBY

1.25 V

0.4 V

23 PA

OVPoff = 1.25V x

R1 + R2 + R3

UVLOoff = 1.25V x

R1 + R2 + R3

R2 + R3

LM5035C

SNVS631D – JANUARY 2010 – REVISED OCTOBER 2016

www.ti.com

Product Folder Links: LM5035C

Submit Documentation Feedback

The impedance seen looking into the resistor divider from the UVLO and OVP pins determines the hysteresis

level. UVLO and OVP enable and disable thresholds are calculated using the equations in the table below for the

three-resistor divider illustrated in Figure 22.

Table 2. UVO/OVP Divider Formulas

DESCRIPTION

FORMULA

Outputs disabled due to VIN falling below UVLO threshold

(11)

Outputs enabled due to VIN rising above UVLO threshold

UVLOon = UVLOoff + (23 µA × R1)

Outputs disabled due to VIN rising above OVP threshold

(12)

Outputs enabled due to VIN falling below OVP threshold

OVPon = OVPoff - [23 µA × (R1 + R2)]

The typical operating ranges of undervoltage and overvoltage thresholds are calculated from the above

equations. For example, for resistor values R1 = 86.6 kΩ, R2 = 2.10 kΩ and R3 = 1.40 kΩ the computed

thresholds are:

•

UVLO turnoff = 32.2 V

•

UVLO turnon = 34.2 V

•

OVP turnon = 78.4 V

•

OVP turnoff = 80.5 V

Figure 23. Remote Standby and Disable Control

To maintain the threshold’s accuracy, TI recommends a resistor tolerance of 1% or better.

The design process starts with the choice of the voltage difference between the UVLO enabling and disabling

thresholds. This will also approximately set the difference between OVP enabling and disabling regulation:

(13)

Next, the combined resistance of R2 and R3 is calculated by choosing the threshold for the UVLO disabling

threshold:

(14)

Then R3 is determined by selecting the OVP disabling threshold:

(15)

Finally, R3 is subtracted from RCOMBINED to give R2:

R2 = RCOMBINED - R3

(16)

LM5035CMH/NOPB датащи(PDF) 28 Page - Texas Instruments

LM5035CMH/NOPB датащи(HTML) 28 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

датащи скачать

ссылки URL