IN

F

BGW

2

F

F

C

C

f

324 kHz

2

R

C

t

t

u S u

u

IN

PD

CM

D

C

C

C

C

47 pF 5 pF 1 pF

53 pF

F

F

3dB

1

1

C

10.3 pF

10 pF

2

R

f

2

309 k

50 kHz

|

u S u

u

u S u

: u

OUT

REF

F

IN

V

V

3.2 V

0.1 V

kV

R

310

309 k

I

10 A

A

|

:

P

REF

V

0.1 V

0.0303

V

3.3 V

1

2

REF

1

2

R

R

V

V

R

R

§

·

u

u ¨

¸

©

¹

OUT

IN

F

REF

V

I

R

V

u

19

LMV321A, LMV358A, LMV324A

www.ti.com

SBOS923B – DECEMBER 2017 – REVISED JUNE 2018

Product Folder Links: LMV321A LMV358A LMV324A

Submit Documentation Feedback

Copyright © 2017–2018, Texas Instruments Incorporated

Typical Application (continued)

8.2.2.1 Design Requirements

The design requirements for this design are:

•

Supply Voltage: 3.3 V

•

Input: 0 µA to 10 µA

•

Output: 0.1 V to 3.2 V

•

Bandwidth: 50 kHz

8.2.2.2 Detailed Design Procedure

is defined in Equation 5.

(5)

Where:

(6)

calculated in Equation 7.

(7)

The closest resistor ratio to meet this ratio sets R1 to 11.5 kΩ and R2 to 357 Ω.

The required feedback resistance can be calculated based on the input current and desired output voltage.

(8)

Calculate the value for the feedback capacitor based RF and the desired –3-dB bandwidth, (f-3dB) using

Equation 9.

(9)

capacitance on the IN– pin of the LMV358A which is equal to the sum of the photodiode shunt capacitance,

(CPD) the common-mode input capacitance, (CCM) and the differential input capacitance (CD) as Equation 10

shows.

(10)

The minimum op amp bandwidth is calculated in Equation 11.

(11)

The 1-MHz bandwidth of the LMV3xxA meets the minimum bandwidth requirement and remains stable in this

application configuration.