LTC1696HS6 データシートの表示（PDF） - Linear Technology

部品番号

コンポーネント説明

メーカー

LTC1696HS6

Overvoltage Protection Controller

Linear Technology 

LTC1696

APPLICATIONS INFORMATION

Feedback Inputs

The LTC1696 has two feedback inputs that allow monitor-

ing of two output voltages. The trip point of the internal

comparator is set by an internal reference of 0.88V with

± 2% accuracy. The output voltage, VS, is sensed through

an external resistor divider network (Figure 1). The resis-

tors R1 and R2 values are calculated with the typical trip

point of 0.88V.

R1

R1+ R2

•

VS

=

0.88

R2 = (VS − 0.88) • R1

0.88

As an example, let’s calculate values for R1 and R2 for a

3.3V supply in which an overvoltage indication is required

at +10% (3.63V). First, a value for R1 is chosen based on

the allowable resistor divider string current. This is de-

termined by power dissipation requirements and possible

sensitivity to noise coupling into the resistor divider. In

this exercise, assume the resistor divider current is 20µA.

R1 is calculated from:

R1= VFB = 0.88V = 44k

IDIVIDER 20µA

The nearest 1% value for R1 is 44.2k. Now, calculating

for R2 yields:

R2 = 44.2k • (3.63v − 0.88V) = 138.1k

0.88V

Choosing the nearest 1% value yields 137k.

VS

R2

R1

LTC1696

FB1 +

–

+– VREF = 0.88V

Figure 1

The chosen values for R1 and R2 yield an overvoltage

threshold of 3.608V (+ 9.3%). With worst-case tolerances

applied, the minimum overvoltage threshold is 3.481V

(+5.5%) and the maximum overvoltage threshold is

3.738V (+13.3%).

Reset Function

In the event of an overvoltage condition, the OUT pin of

the LTC1696 is latched into an active high state. The in-

ternal latch is reset by pulling the TIMER/RESET pin low

through an external N-channel MOSFET switch or pulling

VCC voltage below the UVLO trip point of 1.94V.

For more information www.linear.com/LTC1696

1696fb

9

Share Link: