DD320

DD350

DD420

DD450

DD620

DD650

Three, Four, and Six Channel High Current

Drivers

M ultiple independent medium speed drivers w ith

separate input logic mode controls. Logic inputs

are true TTL unit loads.

1.

Inputs are inverting w hen M ode control has a logic

high input.

2.

Inputs are non-inverting w hen M ode control has a

logic low input.

3.

M ode control and input pins are interchangeable

w ithin any one channel.

4.

The negative output current does not vary w ith \/ee

w hich should not exceed -5V w hen driving

grounded anode diodes to avoid high pow er dissi-

pation in the drivers.

5.

The last tw o digits of the part number signif y out-

put current. Other currents are available on

special order.

APPLICATION NOTES

PIN Diode Sw itching Times

PIN diodes are used as RF sw itches because of their

low of f -capacitance/on-resistance product. How ever,

they store a signif icant charge during conduction that

must be removed bef ore they w ill turn of f . Typically,

this is specif ied as storage time (TS), w hich is made to

look better than it might be by rating it w ith a high ratio

of reverse (IR) to f orw ard (IF) current. W hen sw itching

these diodes w ith a non-spiking driver, the typical TS

w ill be multiplied by the specif ied ratio. For example,

the M A 47120 has a TS of 12 ns w ith IF=20 mA and IR=

200 mA . W ith symmetrical currents as delivered by

high current drivers, the TS becomes 120 ns. High

speed drivers supply a spike of several hundred mA at

turn-on and turn-of f to shorten the TS of the PIN diode.

Heat Sinking

The pow er dissipated in PIN diode sw itches is conducted

to the bottom of the package. The thin walls leading to

the top of the package represent a high thermal resistance.

The total pow er in the hybrid is the sum of it own current

drain multiplied by the voltage of each supply plus the output

current of each driver multiplied by the supply voltage less

the V F of the PIN diode.

The total can be substantial especially in the multiple

high current drivers. If your calculations show that the

hybrid should be heat sunk, you may f ind it convenient

to place it top dow n on the PC board so that the bottom

of the hybrid may be mounted directly to the metal

case of your package.

Other Diode Drivers

+5V

Output #1

M ode Control #1

Input #1

Output #2

M ode Control #2

Input #2

Output #3

M ode Control #3

Input #3

Ground

1

11

22

12

645

SQ

M A X

DD320/420/620

DD320/420/620

X X X X

TOP V IEW

V ee (-SV to – 15V )

Output #6

M ode Control #6

Input #6

Output #5

M ode Control #5

Input #5

Output #4

M ode Control #4

Input #4

Ground

500 M IN

TY P

.015

Pkg

Bottom

.067

.150

M A X

M ETA L W ELDED PA CK A GE

In addition to these standard circuits, Spectrum Microwave produces a wide range of custom-designed drivers. These include a dual

ECL-input driver (DD212) and a 28-channel 50 mA driver (DD2850). Spectrum Microwave is also one of the largest custom hybrid

manufacturers in the United States. Please contact the factory or your local representative for a quote on your driver requirements or

your own custom hybrid circuit.