ADN8820

Preliminary Technical Data

Rev. PrB | Page 6 of 9

PIN FUNCTIONS

Name

Pin

Function

Connections

AMPLIFIER INPUTS

IPDIN

3

Input to TIA for EDFA input photodiode

EDFA input photodiode and feedback resistor

LPDIN

6

Input to TIA for laser photodiode

Laser photodiode and feedback resistor

OPDIN

9

Input to TIA for EDFA output photodiode

EDFA output photodiode and feedback resistor

VB

2

Bias voltage for EDFA input and output photodiodes

External bias voltage required

VBLP

5

Bias voltage for laser photodiode

External bias voltage required

CSP

37

Non-inverting input of current sense amplifier

High-side of laser current sense resistor (50 m

Ω typ.)

CSN

38

Inverting input of current sense amplifier

Low-side of laser current sense resistor (50 m

Ω typ.)

LIMIT INPUTS

VLIM

1

Laser diode voltage will not exceed VLIM

External voltage required

ILIM

45

Limits output voltage if LIO > ILIM

External voltage or no connection (defaults to 2.5 V)

OPLIM

47

Limits output voltage if OPO > OPLIM

External voltage or no connection (defaults to 2.5 V)

LPLIM

46

Limits output voltage if LPO > LPLIM

External voltage or no connection (defaults to 2.5 V)

IPMIN

48

Limits output voltage if IPO is lower than IPMIN

External voltage required

ERROR (COMPENSATION) AMPLIFIER (EA)

EANLP

41

Compensation network for laser diode loop

Internally connects inverting input of EA to laser diode

compensation network

EANOP

40

Compensation network for EDFA loop

Internally connects inverting input of EA to EDFA

compensation network

EAOUT

39

Output of compensation amplifier

Internal connection to linear output amplifier

MUX

42

Allows separate compensation for EDFA and laser

diode

Connects to two external compensation networks: one

for EDFA loop, one for laser diode loop

OPCMP

44

Compensation for limiter section

R-C network to ground

SET

8

Sets output power or current based on MODE

settings

External voltage or DAC

POWER OUTPUT AMPLIFIERS

LINOUT

33

Linear amplifier output

Laser diode through 1

Ω series resistor

PGATE

30

PWM switching for PMOS

Gate of external PMOS for PWM output

NGATE

31

PWM switching for NMOS

Gate of external NMOS for PWM output

SWITCH

28

PWM amplifier output

Drains of external NMOS, PMOS, and input of L-C filter

FB

24

Feedback input for PWM amplifier

Output of L-C filter and laser diode

PWMCMP1

23

Compensation for PWM amplifier

Series R-C networks to FB and PWMCMP2

PWMCMP2

22

Compensation for PWM amplifier

Series R-C to PWMCMP1

SS/SB

25

Constant current charges external capacitor to soft-

start PWM output from 0% duty cycle

Optional external FET can pull down and to engage

standby mode

OUTPUT MONITOR VOLTAGES

IPO

4

Output of EDFA input photodiode TIA

Feedback resistor to IPDIN

OPO

10

Output of EDFA output photodiode TIA

Feedback resistor to OPDIN

LPO

7

Output of laser diode photodiode TIA

Feedback resistor to LPDIN

LIO

11

Output of current sense amplifier

DUAL

12

Compares LIO to 90% of ILIM

To SET pin of additional ADN8820 device in multi-

pump optical amplifier applications

EAOUT

39

Output of compesnation amplifier

Internal connection to linear output amplifier

OSCILLATOR SECTION

SYNCIN

27

Optional clock input signal for PLL

Ground or external clock

SYNCOUT

26

Follows rising edge of SYNCIN plus phase shift

Optional connection to SYNCIN of additional ADN8820

device

CMPOSC

16

Compensation for synchronizing PLL

R-C network to ground

PHASE

17

Sets rising edge phase shift of SYNCOUT

External voltage or no connection (default is 0.7V)

RT

15

Sets PWM clock frequency