AD5170 Analog Devices, AD5170 Datasheet - Page 15

• Manufacturer Part Number: AD5170
• Description: 256-Position Two-Time Programmable I2C Digital Potentiometer
• Manufacturer: Analog Devices

For users who operate their systems at 2.7 V, use of the
bidirectional low threshold P-Ch MOSFETs is recommended
for the supply’s isolation. As shown in Figure 39, this assumes
that the 2.7 V system voltage is applied first, and that the P1 and
P2 gates are pulled to ground, thus turning on P1 and subse-
quently P2. As a result, V
When the AD5170 setting is found, the factory tester applies the
6 V to V
turn them off. The OTP command is executed at this time to
program the AD5170; the 2.7 V source is therefore protected.
Once the OTP is completed, the tester withdraws the 6 V and
the AD5170’s setting is fixed permanently.
AD5170 achieves the OTP function through blowing internal
fuses. Users should always apply the 6 V one time program
voltage requirement at the first program command. Failure to
comply with this requirement may lead to the change of fuse
structures, rendering programming inoperable.
2.7V
Figure 39. Isolate 6 V OTP Supply from 2.7 V Normal Operating Supply.
6V
10kΩ
DD
R1
The 6 V supply must be removed once OTP is completed
; the 6 V is also applied to the gates of P1 and P2 to
P1=P2=FDV302P, NDS0610
P1
APPLY FOR OTP ONLY
P2
DD
1µF
C1
of the AD5170 approaches 2.7 V.
1nF
C2
V
DD
AD5170
Rev. 0 | Page 15 of 24
LAYOUT CONSIDERATIONS
It is a good practice to employ compact, minimum lead length
layout design. The leads to the inputs should be as direct as
possible with a minimum conductor length. Ground paths
should have low resistance and low inductance.
Note that the digital ground should also be joined remotely to
the analog ground at one point to minimize the ground bounce.
V
DD
1µF
Figure 40. Power Supply Bypassing
C1
+
1nF
C2
V
DD
AD5170
GND
AD5170