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P0024-03

GND

VCC

MOD–

MOD+

VCC

BIAS

18

17

16

15

14

13

1

2

3

4

5

6

GND

VCC

DIN+

DIN–

VCC

GND

24 23 22 21 20 19

7

8

9

10 11

12

RGE PACKAGE

(TOP VIEW)

ONET4201LD

SLLS677 – NOVEMBER 2005

Figure 3. Pinout of the ONET4201LD in a 4-mm

× 4-mm, 24-Lead QFN Package (Top View)

TERMINAL FUNCTIONS

TERMINAL

I/O

DESCRIPTION

NAME

NO.

APCSET

23

Analog-in

Set photodiode reference current with resistor to GND.

BIAS

13

Analog-out

Laser diode bias current sink. Connect to laser cathode.

CAPC

20

Analog

APC loop capacitor

DIN+

3

CML-in

Noninverted data input. On-chip, 50-

Ω terminated to VCC.

DIN–

4

CML-in

Inverted data input. On-chip, 50-

Ω terminated to VCC.

DISABLE

24

LVTTL-in

Disable modulation and bias current outputs.

FLTMODE

10

CMOS-in

Fault mode selection input. If a low level is applied to this pin, any fault event is latched and the

bias and modulation currents are disabled in a fault condition. Toggling of DISABLE or VCC

resets the fault condition. If pin is set to a high level, fault events are flagged at the SDOWN

output but not latched. The bias and modulation currents are not disabled. SDOWN is reset

once the fault condition disappears.

GND

1, 6, 18, EP

Supply

Circuit ground. The exposed die pad (EP) must be grounded.

IBMAX

21

Analog-in

Set maximum laser diode current with resistor to GND.

MOD+

15

Analog-out

Laser modulation current output. Connect to laser cathode. Avoid usage of vias on board.

MOD–

16

Analog-out

Complementary laser modulation current output. Connect to VCC adjacent to anode of laser

diode. Avoid usage of vias on board.

MODSET

11

Analog-in

Set temperature-independent modulation current with resistor to GND.

MODTC

12

Analog-in

Set modulation-current temperature compensation with resistor to GND.

MONB

8

Analog-out

Bias current monitor sources 1/68 of the bias current

MONP

7

Analog-out

Photodiode current monitor sources a current identical to the photodiode current

OUTPOL

22

LVTTL-in

Alters modulation current output polarity. Open or high: normal polarity, low: inverted polarity.

OUTPOL is pulled up internally. Normal polarity: when DIN+ is high, current is sunk into MOD+.

PD

19

Analog-in

Monitor photodiode input. Connect to photodiode anode for APC. Sinks the photodiode current

to GND.

SDOWN

9

LVTTL-out

Fault detection flag

VCC

2, 5, 14, 17

Supply

3.3 V

±10% supply voltage

7

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