MAX999AAUKT Ver la hoja de datos (PDF) - Maxim Integrated

Número de pieza

componentes Descripción

Fabricante

MAX999AAUKT

Single/Dual/Quad, Ultra-High-Speed, +3V/+5V, Beyond-the-Rails Comparators

Maxim Integrated 

MAX961–MAX964/

MAX997/MAX999

Single/Dual/Quad, Ultra-High-Speed, +3V/+5V,

Beyond-the-Rails Comparators

VCC

ISOURCE

MAX961–MAX964

MAX997

MAX999

Q, Q

GND

ISINK

Figure 4. Output Stage Circuitry

Figure 5. MAX961 PCB Layout

Output Stage Circuitry

The MAX961–MAX964/MAX997/MAX999 contain a cur-

rent-driven output stage, as shown in Figure 4. During an

output transition, ISOURCE or ISINK is pushed or pulled to

the output pin. The output source or sink current is high

during the transition, creating a rapid slew rate. Once the

output voltage reaches VOH or VOL, the source or sink

current decreases to a small value, capable of maintain-

ing the VOH or VOL in static condition. This decrease in

current conserves power after an output transition has

occurred.

One consequence of a current-driven output stage is a

linear dependence between the slew rate and the load

capacitance. A heavy capacitive load slows down the volt-

age output transition.

Shutdown Mode

When SHDN is high, the MAX961/MAX963/MAX964/

MAX997 shut down. When shut down, the supply current

drops to 270μA per comparator, and the outputs become

high impedance. SHDN has a high input impedance.

Connect SHDN to GND for normal operation. Exit shut-

down with LE low; otherwise, the output is indeterminate.

Applications Information

Circuit Layout and Bypassing

The MAX961–MAX964/MAX997/MAX999’s high band-

width requires a high-speed layout. Follow these layout

guidelines:

1) Use a PCB with a good, unbroken, low-inductance

ground plane.

2) Place a decoupling capacitor (a 0.1μF ceramic sur-

face-mount capacitor is a good choice) as close to

VCC as possible.

3) On the inputs and outputs, keep lead lengths short to

avoid unwanted parasitic feedback around the com-

parators. Keep inputs away from outputs. Keep imped-

ance between the inputs low.

4) Solder the device directly to the printed circuit board

rather than using a socket.

5) Refer to Figure 5 for a recommended circuit layout.

6) For slow-moving input signals, take care to prevent

parasitic feedback. A small capacitor (1000pF or less)

placed between the inputs can help eliminate oscil-

lations in the transition region. This capacitor causes

negligible degradation to tPD when the source imped-

ance is low.

www.maximintegrated.com

Maxim Integrated │  10

Share Link: