AD9661A データシートの表示（PDF） - Analog Devices

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AD9661A

Laser Diode Driver with Light Power Control

Analog Devices 

AD9661A

Pin

OUTPUT

POWER LEVEL

CAL

HOLD

PULSE

PULSE 2

SENSE IN

GAIN

POWER MONITOR

DISABLE

VREF

+VS

GROUND

LEVEL SHIFT IN

LEVEL SHIFT OUT

Function

PIN DESCRIPTIONS

Analog laser diode current output. Connect to cathode of laser diode, anode connected to +VS externally.

Analog voltage input, VREF to VREF + 1.6 V. Output current is set proportional to the POWER LEVEL

during

calibration

as follows: IMONITOR

= VPOWER LEVEL – VREF

RGAIN + 50 Ω

TTL/CMOS compatible, feedback loop T/H control signal. Logic LOW enables calibration mode, and

the feedback loop T/H goes into track mode 13 ns after (the aperture delay) PULSE goes logic HIGH

(there is no aperture delay if PULSE goes high before CAL transitions to a LOW level). Logic HIGH dis-

ables the T/H and immediately places it in hold mode. PULSE should be held HIGH while calibrating.

Floats logic HIGH.

External hold capacitor for the bias loop T/H. Approximate droop in the output current while CAL is

logic HIGH is:

± ∆IOUT

= 18 × 10–9 tHOLD

CHOLD

E Bandwidth of the loop is:

BW

≈

2

π

(550

1

Ω)

CHOLD

TTL/CMOS compatible, current control signal. Logic HIGH supplies IOUT to the laser diode. Logic

T LOW turns IOUT off. Floats logic HIGH.

TTL/CMOS compatible, current control signal. Logic LOW supplies IOUT to the laser diode. Logic

HIGH turns IOUT off. Floats logic HIGH.

E Analog current input, IMONITOR, from PIN photo detector diode. SENSE IN should be connected to the

anode of the PIN diode, with the PIN cathode connected to +VS or another positive voltage. Voltage at

SENSE IN varies slightly with temperature and current, but is typically 1.0 V.

L External connection for the feedback network of the transimpedance amplifier. External feedback network,

RGAIN and CGAIN, should be connected between GAIN and POWER MONITOR. See text for choosing

values.

Output voltage monitor of the internal feedback loop. Voltage is proportional to feedback current from

photo diode, IMONITOR.

O TTL/CMOS compatible, current output disable circuit. Logic LOW for normal operation; logic HIGH

disables the current outputs to the laser diode, and drives the voltage on the hold capacitors close to VREF

(minimizes the output current when the device is re-enabled). DISABLE floats logic HIGH.

S Analog Voltage output, internal bandgap voltage reference, ~1.8 V, provided to user for power level offset.

Power Supply, nominally +5 V. All +VS connections should be tied together externally.

Ground reference. All GROUND connections should be tied together externally.

B Analog input to the on board level shift circuit. Input Range 0.1 V – 1.6 V.

Voltage output from on board level shift circuit. Connect to POWER LEVEL externally to use the on

board level shift circuit. Output voltage is VLEVEL SHIFT OUT = VLEVEL SHIFT IN +VREF.

O PIN ASSIGNMENTS

PULSE2 1

DNC 2

VREF 3

LEVEL SHIFT IN 4

GAIN 5

POWER MONITOR 6

SENSE INPUT 7

GROUND 8

+VS 9

GROUND 10

HOLD 11

POWER LEVEL 12

LEVEL SHIFT OUT 13

DISABLE 14

AD9661AKR

(Not to Scale)

–4–

28 +VS

27 GROUND

26 OUTPUT

25 GROUND

24 OUTPUT

23 GROUND

22 OUTPUT

21 GROUND

20 OUTPUT

19 GROUND

18 +VS

17 GROUND

16 CAL

15 PULSE1

REV. 0

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