Datasheet

Ex_UVP

PVDD_LD

InternalPVDD

AMP Enable

1.25 V

Bandgap

Comparator

23PVDD_HP

Ex _UVP

External

sense

Voltage

1.25V

Bandgap

Comparator

DRV604

5uA

Component Selection

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This topology demands a unity gain stable opamp, if that's not the case, a capacitor from inverting input to

GND of the same value as C1 is used. That increases the high frequency gain to 2.

The component values can be calculated with the help of the TI FilterPro™ program available on:

http://focus.ti.com/docs/toolsw/folders/print/filterpro.html

In Table 3 various proposals for the filter and gain settings can be found.

Table 3. DRV604PWPEVM Filter Specifications

C10, C15, C7, C12 C9, C14, R8, R18 R11, R21 R12, R22

EVM Reference Designators

C20, C23 C17, C22 C19, C21 R26, R7 R29, R9 R30, R10

Gain High Pass Low Pass C1 C2 C3 R1 R2 R3

–1 V/V 1.6 Hz 40 kHz 100 pF 680 pF 10 mF 10 kΩ 10 kΩ 24 kΩ

–1.5 V/V 1.3 Hz 40 kHz 68 pF 680 pF 15 mF 8.2 kΩ 12 kΩ 30 kΩ

–2 V/V 1.6 Hz 40 kHz 33 pF 330 pF 6.8 mF 15 kΩ 30 kΩ 47 kΩ

–2 V/V 1.6 Hz 30 kHz 47 pF 470 pF 6.8 mF 15 kΩ 30 kΩ 43 kΩ

–3.33 V/V 1.2 Hz 40 kHz 33 pF 470 pF 10 mF 13 kΩ 43 kΩ 43 kΩ

–10 V/V 0.6 Hz 30 kHz 22 pF 1 nF 22 mF 4.7 kΩ 47 kΩ 27 kΩ

The resistor values should be low value to achieve low noise, but should be of high enough value to

obtain a small size ac-coupling capacitor.

4.4 Internal and External Under Voltage Detection and RESET Output

The DRV604 contains an internal precession band gap reference voltage and 2 comparators, one is used

to monitor the supply voltage, PVDD_AB and PVDD_CD, the other to monitor an external user selectable

voltage on pin 25. The internal PVDD monitor is set at 2.8V with 200mV hysteresis.

The external under voltage detection can be used to shutdown the DRV604 before an input device can

make a pop. The shutdown threshold at the UVP pin is 1.25V. A resistor divider is used to obtain the

shutdown threshold and hysteresis desired for the application.

DRV604PWPEVM SLOU288–February 2010

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