MP230 查看數據表（PDF） - Cirrus Logic

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MP230

Power Operational Amplifier

Cirrus Logic 

MP230

Product Innova tionFrom

required. See Q1 and Q2 in Figure 1. In either case the differential

input voltage will be clamped to ±0.7V. This is sufficient overdrive

+Vs Z1

to produce the maximum power bandwidth. Some applications will

also need over-voltage protection devices connected to the power

supply rails. Unidirectional zener diode transient suppressors are

recommended. The zeners clamp transients to voltages within -IN

1

42

+Vs

+Vb

2

the power supply rating and also clamp power supply reversals

GND

to ground. Whether the zeners are used or not the system power

supply should be evaluated for transient performance including Q1

power-on overshoot and power-off polarity reversals as well as

Q2

OUT

line regulation. See Z1 and Z2 in Figure 1.

POWER SUPPLY BYPASSING

+IN

Bypass capacitors to power supply terminals +VS and -VS must

be connected physically close to the pins to prevent local para-

41

GND

-Vb

-Vs

40

38

sitic oscillation in the output stage of the MP230. Use electrolytic

capacitors at least 10µF per output amp required. Bypass the

electrolytic capacitors with high quality ceramic capacitors 0.1µF

Z2

-Vs

or greater. In most applications power supply terminals +VB and

-VB will be connected to +VS and -VS respectively. Although +VB

FIGURE 1: OVERVOLTAGE PROTECTION

and -VB are bypassed internally it is recommended to bypass +VB and -VB with 0.1µF externally. Additionally, ground

pins 2 and 40 must be connected to the system signal ground.

CURRENT LIMIT

The two current limit sense lines are to be connected directly

RF

across the current limit sense resistor. For the current limit to work

correctly pin 36 must be connected to the amplifier output side and IN RIN 42

pin 35 connected to the load side of the current limit resistor RLIM

as shown in Figure 2. This connection will bypass any parasitic re-

35

-ILIM 36

+ILIM

OUT

sistances RP, formed by socket and solder joints as well as internal

41

amplifi er losses.The current limiting resistor may not be placed

RP RLIM

RL

anywhere in the output circuit except where shown in Figure 2.

The value of the current limit resistor can be calculated as follows:

RLIM = .65/ILIMIT

FIGURE 2: 4 WIRE CURRENT LIMIT

BOOST OPERATION

With the boost feature the small signal stages of the amplifier are operated at a higher supply voltages than the

amplifier’s high current output stage. +VB (pin 1) and -VB (pin 38) are connected to the small signal stages. An addi-

tional 10V on the +VB and -VB pin is sufficient to allow the small signal stages to drive the output stage into the triode

region and improve the output voltage swing for extra efficient operation when required. When the boost feature

is not needed +VS and -VS are connected to +VB and -VB respectively. +VB and -VB must not be operated at supply

voltages less than +VS and -VS respectively.

SHUTDOWN

The output stage is turned off by applying a 5V level to HSD (pin 8) relative to LSD (pin 7). This is a non-latching

circuit. As long as HSD remains high relative to LSD the output stage will be turned off. LSD will normally be tied to

signal ground but LSD may float from -VB to +VB - 15V. Shutdown can be used to lower quiescent current for standby

operation or as part of a load protection circuit.

BIAS CLASS OPTION

Normally pin 5 (Iq) is left open. But when pin 5 is connected to pin 6 (Cc1) the quiescent current in the output stage

is disabled. This results in lower quiescent power, but also class C operation of the output stage and the resulting

crossover distortion. In many applications, such as driving motors, the distortion may be unimportant and lower

standby power dissipation is an advantage.

6

MP230U

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