Home >> AD5170 Search >> Analog Devices AD5170 Datasheet
AD5170 Datasheet
I2C Digital Potentiometer
Analog Devices
Analog Devices


No Preview Available !

AD5170 pdf
ESD PROTECTION
All digital inputs, SDA, SCL, AD0, and AD1, are protected with
a series input resistor and parallel Zener ESD structures, as shown
in Figure 37 and Figure 38.
340
LOGIC
GND
Figure 37. ESD Protection of Digital Pins
A, B, W
GND
Figure 38. ESD Protection of Resistor Terminals
TERMINAL VOLTAGE OPERATING RANGE
The AD5170 VDD-to-GND power supply defines the boundary
conditions for proper 3-terminal digital potentiometer opera-
tion. Supply signals present on Terminal A, Terminal B, and
Terminal W that exceed VDD or GND are clamped by the internal
forward-biased diodes (see Figure 39).
VDD
A
W
B
GND
Figure 39. Maximum Terminal Voltages Set by VDD and GND
POWER-UP SEQUENCE
Because the ESD protection diodes limit the voltage compliance
at Terminal A, Terminal B, and Terminal W, it is important to
power VDD/GND before applying any voltage to Terminal A,
Terminal B, and Terminal W (see Figure 39). Otherwise, the
diode is forward-biased such that VDD is powered unintentionally
and may affect the rest of the user’s circuit. The ideal power-up
sequence is GND, VDD, the digital inputs, and then VA/VB/VW.
The relative order of powering VA, VB, VW, and the digital inputs
is not important as long as they are powered up after GND/VDD.
POWER SUPPLY CONSIDERATIONS
To minimize the package pin count, both the one-time pro-
gramming and normal operating voltage supplies share the
same VDD terminal of the AD5170. The AD5170 employs fuse
link technology that requires 5.6 V to 5.8 V for blowing the
internal fuses to achieve a given setting, but normal VDD can be
anywhere between 2.7 V and 5.5 V after the fuse programming
process. As a result, dual voltage supplies and isolation are needed if
system VDD is lower than the required VDD_OTP. The fuse program-
ming supply (either an on-board regulator or rack-mount power
supply) must be rated at 5.6 V to 5.8 V and be able to provide a
100 mA current for 400 ms for successful OTP.
AD5170
When the fuse programming is complete, the VDD_OTP supply
must be removed to allow normal operation at 2.7 V to 5.5 V,
and the device consumes current in the μA range.
5.7V
R1
APPLY FOR OTP ONLY
10k
2.7V
VDD
C1 C2
P1 P2 10µF 0.1µF
AD5170
P1 = P2 = FDV302P, NDS0610
Figure 40. Isolate 5.7 V OTP Supply from 2.7 V Normal Operating Supply
For example, for those who operate their systems at 2.7 V, use of
the bidirectional, low threshold, P-Channel MOSFETs is recom-
mended for the isolation of the supply. As shown in Figure 40,
this assumes that the 2.7 V system voltage is applied first, and
the P1 and P2 gates are pulled to ground, thus turning on P1 and,
subsequently, P2. As a result, VDD of the AD5170 approaches 2.7 V.
When the AD5170 setting is found, the factory tester applies the
VDD_OTP to both the VDD and the MOSFETs gates, turning off P1
and P2. The OTP command is executed at this time to program the
AD5170 while the 2.7 V source is protected. When the fuse pro-
gramming is complete, the tester withdraws the VDD_OTP and the
setting for the AD5170 is permanently fixed.
The AD5170 achieves the OTP function by blowing internal
fuses. Users should always apply the 5.6 V to 5.8 V one-time-
program voltage requirement at the first fuse programming
attempt. Failure to comply with this requirement can lead to a
change in the fuse structures, rendering programming inoperable.
Care should be taken when SCL and SDA are driven from a low
voltage logic controller. Users must ensure that the logic high
level is between 0.7 V × VDD and VDD + 0.5 V. Refer to the Level
Shifting for Different Voltage Operation section.
Poor PCB layout introduces parasitics that can affect the fuse
programming. Therefore, it is recommended to add a 10 μF
tantalum capacitor in parallel with a 1 nF ceramic capacitor as
close as possible to the VDD pin. The type and value chosen for
both capacitors are important. This combination of capacitor
values provides both a fast response and larger supply current
handling with minimum supply droop during transients. As a
result, these capacitors increase the OTP programming success
by not inhibiting the proper energy needed to blow the internal
fuses. Additionally, C1 minimizes transient disturbance and low
frequency ripple, and C2 reduces high frequency noise during
normal operation.
Rev. G | Page 17 of 24

AD5170 Datasheet PDF



Related Start with AD517*

[ AD5170 Analog Devices ]     [ AD5171 Analog Devices ]     [ AD5172 Analog Devices ]     [ AD5173 Analog Devices ]     [ AD5174 Analog Devices ]     [ AD5175 Analog Devices ]     [ AD510 Analog Devices ]     [ AD5100 Analog Devices ]     [ AD5110 Analog Devices ]     [ AD5111 Analog Devices ]     [ AD5112 Analog Devices ]     [ AD5113 Analog Devices ]     [ AD5114 Analog Devices ]     [ AD5115 Analog Devices ]     [ AD5116 Analog Devices ]     [ AD5121 Analog Devices ]    


Searches related to AD5170 part

Find Chips CBC RS online RUTRONIK 24
Component Distributors NexGen Digital Richardson RFPD ICC
Beyond Components NAC PEI-Genesis Powell Electronics
TME Ameya 360 Power & Signal Datasheets360
Freelance Electronics Sager Electronics Terminals & Connectors TTI

0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z
@ 2014 :: DatasheetsPDF.com :: Semiconductors Datasheet Search & Download Site