9

9122F–AUTO–03/10

ATA6833/ATA6834 [Preliminary]

Example:

Using an external resistor R

T

t

t

t

Hence, the minimum time the external microcontroller has to wait before pin WD can be trig-

gered is in worst case t

WD pin is t

t

Other values can be set up by picking a different resistor value for R

on the value of R

Figure 3-5.

T

3.5

Charge Pump

A charge pump has been implemented in order to provide sufficient voltage to operate the exter-

nal high-side power-NMOS transistors and the VG regulator, which drives the low-side

Power-NMOS transistors. The charge pump output voltage at CPOUT pin is controlled to settle

typically about 15V above the voltage at pin PBAT. A built-in supervisor circuit checks if the out-

put voltage is sufficient to operate the VG regulator and external Power-NMOS transistors. The

output voltage is accepted as good when it rises above VCP

flagged at DG2 if this minimum can not be reached or if the output voltage drops below the lower

threshold of VCP

The two shuffle capacitors should have the same value. The value of the reservoir capacitor

should be at least twice the value of one shuffle capacitor. Two external shuffle capacitors and

an external reservoir capacitor have to be provided. The typical values for the two shuffle

capacitor is 100 nF, and for the reservoir capacitor is 470 nF. All capacitors should be ceramic. It

is advisable to pick a reservoir capacitor with twice or three-times the size of the two

equally-sized shuffle capacitors. The greater the capacitors, the greater the output current

capability.

T

0

5

10

15

20

25

30

35

40

45

10

20

30

40

50

60

70

80

90

10 0

T

T