MAX9636EVKIT+ - Maxim Integrated

_______________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

MAX9636 Evaluation Kit

Evaluates: MAX9636

General Description

The MAX9636 evaluation kit (EV kit) is an assembled

and tested PCB used to evaluate the MAX9636 low-

power, low-noise, CMOS input op amp, which is suitable

for photodiode transimpedance front-ends in portable

medical instruments. The EV kit is preconfigured for

a transimpedance amplifier (TIA). Additionally, an on-

board LED driver circuit provides a controlled light

source to help evaluate the performance of the MAX9636

TIA circuit. The EV kit can easily be adapted to act as

noninverting, inverting, or differential amplifier by chang-

ing a few components. Another EV kit is offered for the

MAX9638 dual version of this op amp to enable evalua-

tion in an active filter circuit configuration.

The EV kit comes with a MAX9636AXT+ installed.

Features

S Accommodates Multiple Op-Amp Configurations

S On-Board LED Driver

S Accommodates Multiple Wavelength LEDs

S Proven PCB Layout

S Fully Assembled and Tested

Ordering Information

19-5287; Rev 0; 5/10

+Denotes lead(Pb)-free and RoHS compliant.

Component List

Component Suppliers

Note: Indicate that you are using the MAX9636 when contacting these component suppliers.

PART TYPE

MAX9636EVKIT+ EV Kit

DESIGNATION QTY DESCRIPTION

C1 1

18pF Q5%, 50V C0G ceramic

capacitor (0603)

TDK C1608C0G1H180J

C2, C7, C8, C9 4

0.1FF Q10%, 16V X7R ceramic

capacitors (0603)

Murata GRM188R71C104K

C3, C6 0 Not installed, ceramic capacitors

(0603)

C4 0 Not installed, ceramic capacitor

(0805)

C5 1

4.7FF Q10%, 25V X5R ceramic

capacitor (0805)

Murata GRM21BR61E475K

D1 1

Red side LED

(4mm x 3.6mm x 4mm)

OSRAM LS A676-R1S1

DESIGNATION QTY DESCRIPTION

D2 1 Photodiode

Vishay BPW46

JU1, JU2 2 3-pin headers

M1 1 n-channel MOSFET (6 SC70)

Fairchild FDG410NZ

R1, R6, R7 3 0I Q5% resistors (0603)

R2 1 10kI Q1% resistor (0603)

R3, R9, R12 0 Not installed, resistors (0603)

R4 1 100kI Q1% resistor (0603)

R5 1 249I Q1% resistor (0603)

R8, R10, R11 3 976I Q1% resistors (0603)

TP1 1 Red test point

U1, U2 2 Low-power op amps (6 SC70)

Maxim MAX9636AXT+

— 2 Shunts

— 1 PCB: MAX9636 EVALUATION

KIT+

SUPPLIER PHONE WEBSITE

Fairchild Semiconductor 888-522-5372 www.fairchildsemi.com

Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com

TDK Corp. 847-803-6100 www.component.tdk.com

Vishay 402-563-6866 www.vishay.com

MAX9636 Evaluation Kit

Evaluates: MAX9636

2 ______________________________________________________________________________________

Quick Start

Required Equipment

• MAX9636 EV kit

• 2.1V to 5.5V DC power supply (e.g., Agilent E3620A)

• Function generator (e.g., Agilent 33220A)

• Digital oscilloscope (e.g., Tektronix TDS3014)

Procedure

The EV kit is fully assembled and tested. Follow the

steps below to verify board operation. Caution: Do

not turn on power supply until all connections are

completed.

1) Since the photodiode on the EV kit is sensitive to

ambient and infrared light, it is recommended that

the EV kit be placed in a suitable dark environment

to minimize the idling current.

2) Verify that a shunt is installed in the 1-2 position

of both jumpers JU1 and JU2. See Table 1 for a

description of the jumper settings.

3) Set the DC power supply to 5V and connect the

positive terminal to the VDD and INP pads on the EV

kit. Connect the negative terminal to the GND pad.

4) Set the function generator for a square-wave

frequency of 1kHz, and amplitude to 2VP-P with a

DC offset of 1V.

5) Disable the function generator.

6) Connect the function generator across the

VCONTROL and GND pads on the EV kit.

7) Connect an oscilloscope channel across the VOUT

and GND pads on the EV kit.

8) Turn on the DC power supply.

9) Enable the function generator.

10) Verify that the red LED (D1) turns on. At 1kHz, the

LED pulsing cannot be seen due to persistence of

vision. Verify that the oscilloscope screen shows

a square waveform with an approximate 1kHz

frequency.

Detailed Description of Hardware

The MAX9636 EV kit is an assembled and tested PCB

used to evaluate the MAX9636 low-power op amp, which

is suitable for photodiode transimpedance front-ends in

portable medical instruments. The EV kit is preconfig-

ured for a TIA, but can easily be adapted to other topolo-

gies by changing a few components.

Transimpedance Amplifier (TIA)

By default, the EV kit is set up for a TIA. The output volt-

age of the TIA is the photodiode current multiplied by the

feedback resistor:

OUT PD OS

V (I x R4) + V=

where R4 comes installed as a 100kI resistor, IPD is

defined as photodiode current, and VOS is the input off-

set voltage of the op amp. Use capacitor C1 to stabilize

the op amp by rolling off high-frequency gain due to the

photodiode capacitance.

For ease of evaluation of the TIA circuit, LED D1 is

provided on-board to emit light from the side. A second

op amp (U2), MOSFET M1, and resistors R8, R10, and

R11 form a controlled current-sink circuit to regulate

the LED current. Due to the negative feedback action,

the voltage at test point TP1 is the same as the control

voltage (VCONTROL). The LED current is given by the

following equation:

LED VCONTROL

I(R8 R10 R12)

=

Table 1. Jumper Descriptions (JU1, JU2)

*Default position.

JUMPER SHUNT POSITION DESCRIPTION

JU1 1-2* Connects the SHDN pin of the MAX9636 (U1) to VDD for normal operation.

2-3 Connects the SHDN pin of the MAX9636 (U1) to GND to put the part in shutdown mode.

JU2

1-2* Powers LED D1 using the supply applied at the VDD pad of the EV kit.

2-3 Powers LED D1 and its LED driver circuit using a separate power supply applied at the

VLED pad on the EV kit.

MAX9636 Evaluation Kit

Evaluates: MAX9636

_______________________________________________________________________________________ 3

Table 2. List of LEDS With the Same

Footprint as D1

Since the forward-voltage drop across the LED is

approximately 2V, the applied control voltage ranges

from 0V to VDD1 - 2V.

The silicon pin photodiode (BPW46) has a spectral

bandwidth that ranges from 430nm to 1100nm. Hence,

the EV kit can also be used with LEDs that range from

visible light to infrared light. Table 2 gives a list of LEDs

that have the same footprint as installed LED D1, but with

different wavelengths. When changing D1, replace R8,

R10, R11, and R12 with the appropriate resistor values.

Noninverting Configuration

The EV kit can also be configured as a noninverting

amplifier. Remove D2, R5, C1, and C2 from the EV kit.

Replace R2 with a 0I resistor. The gain is set by the

ratio of R4 and R1 when a voltage (VINP) is applied at

the INP pad and the INM pad is connected to ground by

installing 0I on R9 on the EV kit. The output voltage for

the noninverting configuration is given by the following

equation:

OUT INP OS

R4

V (1 )(V V )

R1

= + +

Inverting Configuration

The EV kit can also be configured as an inverting

amplifier. Remove D2, R2, R5, and R6 from the EV

kit. Install a 0I resistor across R5 and R3. Install the

decoupling capacitors between C4 and C6. The board

is operated in dual supply (Q1.05V to Q2.75V). The gain

is set by the ratio of R4 and R1 when a voltage (VINM) is

applied at the INM pad. The output voltage for the invert-

ing configuration is given by the following equation:

OUT INM OS

R4

V ( )(V V )

R1

= − +

Differential Amplifier

To configure the EV kit as a differential amplifier, remove

D2 and replace R1, R2, R4, and R5 with the appropri-

ate resistors. Remove or choose appropriate equal

capacitors for C1 and C5. When R1 = R2 and R4 = R5,

the CMRR of the differential amplifier is determined by

matching of ratios R1/R2 and R4/R5.

OUT V INP INM

V A (V V )= −

where:

V

R4 R5

AR1 R2

= =

Shutdown (SHDN)

The MAX9636 (U1) is operational when a shunt is placed

in the 1-2 position on jumper JU1. By placing a shunt in

the 2-3 position, U1 is disabled.

LED Supply

By default, the LED D1 supply uses the same supply

applied at the VDD pad on the EV kit. To use a separate

supply for the LED circuit, move the shunt of jumper JU2

to the 2-3 position and apply a voltage from 2.1V to 5.5V

on the VLED pad on the EV kit.

LED MANUFACTURER

PART NUMBER

WAVELENGTH

(nm) COLOR

OSRAM LB A6SG-S1T2-35 470 Blue

OSRAM LT A673-Q1R2-25 532 Green

OSRAM LY A676-R1S2-26 587 Yellow

OSRAM LO A676-R1S2-24 606 Orange

OSRAM LA A676-R1S2-1 615 Amber

OSRAM SFH426 880 Infrared

OSRAM SFH425 950 Infrared

MAX9636 Evaluation Kit

Evaluates: MAX9636

4 ______________________________________________________________________________________

Figure 1. MAX9636 EV Kit Schematic

MAX9636 Evaluation Kit

Evaluates: MAX9636

_______________________________________________________________________________________ 5

Figure 2. MAX9636 EV Kit Component Placement Guide—

Component Side

Figure 3. MAX9636 EV Kit PCB Layout—Component Side

Figure 4. MAX9636 EV Kit PCB Layout—Solder Side

1.0’’ 1.0’’

1.0’’

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.

Maxim reserves the right to change the circuitry and specifications without notice at any time.

6 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

MAX9636 Evaluation Kit

Evaluates: MAX9636

Revision History

REVISION

NUMBER

REVISION

DATE DESCRIPTION PAGES

CHANGED

0 5/10 Initial release —