AD5252BRUZ1 Analog Devices Inc, AD5252BRUZ1 Datasheet - Page 25

• Manufacturer Part Number: AD5252BRUZ1
• Description: IC DGTL POT DUAL 1K I2C 14-TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD5252BRUZ1

• Taps: 256
• Resistance (ohms): 1K
• Number Of Circuits: 2
• Temperature Coefficient: 650 ppm/°C Typical
• Memory Type: Non-Volatile
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V, ±2.25 V ~ 2.75 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 14-TSSOP
• Resistance In Ohms: 1.00K
• End To End Resistance: 1kohm
• Track Taper: Linear
• Resistance Tolerance: ± 30%
• No. Of Steps: 256
• Supply Voltage Range: 2.7V To 5.5V, ± 2.25V To ± 2.75V
• Control Interface: I2C, Serial
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AD5252EVAL - BOARD EVAL FOR AD5252
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

APPLICATIONS INFORMATION
LCD PANEL V
Large LCD panels usually require an adjustable V
centered around 6 V to 8 V with ±1 V swing and small steps
adjustment. This example represents common DAC appli-
cations where the window of adjustments is small and centered
at any level. High voltage and high resolution DACs can be
used, but it is far more cost-effective to use low voltage digital
potentiometers with level shifting, such as the AD5251 or
AD5252, to achieve the objective.
Assume a V
step adjustment, as shown in Figure 44. The AD5252 can be
configured in voltage divider mode with an op amp gain. With
±20% tolerance accounted for by the AD5252, this circuit can
still be adjusted from 5 V to 7 V with an 8 mV/step in the
worst case.
CURRENT-SENSING AMPLIFIER
The dual-channel, synchronous update, and channel-to-channel
resistance matching characteristics make the AD5251/AD5252
suitable for current-sensing applications, such as LED
brightness control. In the circuit shown in Figure 45, when
RDAC1 and RDAC3 are programmed to the same settings, it
can be shown that
As a result, the current through a sense resistor connected
between V
The circuit can be programmed for use with systems that require
different sensitivities. If the op amp has very low offset and low
bias current, the major source of error comes from the digital
potentiometer channel-to-channel resistance mismatch, which
is typically 0.15%. The circuit accuracy is about 9 bits, which is
adequate for LED control and other general-purpose applications.
Figure 44. Apply 5 V Digital Potentiometer AD5251 in a 6 V ± 1 V Application
V
+5V
o
=
2
1
COM
and V
N
U1
AD5252
V
D
−
DD
voltage requirement of 6 V ± 1 V with a ±20 mV
18.5kΩ
350kΩ
D
COM
10kΩ
2
(
R1
R2
R3
V
+14.4V
can be determined.
B
2
ADJUSTMENT
−
±1%
±20%
V
1
)
+
V
1kΩ
R5
REF
6kΩ
+14.4V
R4
V+
V–
2.2pF
C1
U2
COM
6V ± 1V
voltage
V
COM
(8)
Rev. B | Page 25 of 28
ADJUSTABLE HIGH POWER LED DRIVER
Figure 46 shows a circuit that can drive three or four high power
LEDs. The ADP1610 is an adjustable boost regulator that provides
adequate headroom and current for the LEDs. Because its FB pin
voltage is 1.2 V, the digital potentiometer AD5252 and the op amp
form an average gain of 12 feedback networks that servo the
sensing and feedback voltages. As a result, the voltage across
R
setting. An adjustable LED current is
R
to limit the maximum LED current. R3 should be used in parallel
with the AD5252 to limit the LED current to an achievable range.
+5V
SET
SET
should be small enough to conserve power, but large enough
is regulated around 0.1 V, depending on the AD5252’s
I
R
LED
SENSE
0.1kΩ
V
V
C2
10μF
1
2
=
V
R
Figure 46. High Power, Adjustable LED Driver
R
390pF
SET
PWM
100kΩ
SET
U1
C
Figure 45. Current-Sensing Amplifier
R
C
O
RDAC1
AD5252
RDAC3
10kΩ
10kΩ
U2
SD
FB
COMP
SS
B
B
10nF
ADP1610
C
SS
RT
1.1kΩ
GND
IN
SW
R2
0.1μF
U1
C8
AD8628
AD8591
+5V
V–
V+
AD5251/AD5252
V+
V–
L1
10μF
U1
+5V
B
U3
W
10kΩ
200Ω
U2
R3
D1
10μF
AD5252
C3
A
V
VREF
0.25kΩ
100Ω
O
R1
R
SET
(9)
D1
D2
D3
V
OUT