SML2120

Pin Descriptions

Summit Microelectronics

2066 6.3 1/22/04

5

12

O

VBRIDGE

Connection to an external Full-Bridge Sensor when used with the Thermistor pin.

Two of the full-bridge resistors are internal. See the Bridge Circuit Diagram in

Figure 1 and 3. Voltage level is 0.2V with respect to VSS.

13

I/O

ILU0

Current output resulting from Lookup Table 0. User-programmable to either sink

(to VSS) or source (to VDD) up to 2.5mA.

14

I/O

ILU1

Current output resulting from Lookup Table 1. User-programmable to either sink

(to VSS) or source (to VDD) up to 2.5mA.

15

PWR

VDD

VDD is the positive rail for most internal functions.

16

I

C2

APC integrator.

17

I

C1

18

I

MPD

Monitor Photo Diode anode input. Connect a resistor between MPD and C1 to

19

I

VBURST

In burst mode, this input supplies a ballast current that allows the SML2120 to

quickly restart when ENA# is asserted.

20

I

BIAS

Supplies the main laser current as controlled by the APC circuit; capable of

sinking up to 100mA to VSS.

21

PWR

VSS

VSS must be tied to the lowest system voltage potential.

22

I/O

VAPC

APC Override pin.

23

I

EXT_TEMP

This input can be configured to sense either a voltage or current generated from

an external temperature monitoring device.

24

PWR

VDD

VDD is the positive rail for most internal functions.

25

PWR

VHI

In dual-voltage rail systems, VHI is tied to the system logic high potential. It is the

logic high reference for all pins marked with an asterisk (*).

26

O

Analog output voltage indicating the state of the Monitor Photo Diode (MPD)

input.

27

O

Analog output voltage proportional to the temperature as sensed by the

EXT_TEMP or THERMISTOR input.

28

O

Analog output voltage proportional to BIAS current.

* See VLOW and VHI pin descriptions.

Pin Number Pin Type

Pin Name

Description