AD1580BRTZ-REEL7 Analog Devices Inc, AD1580BRTZ-REEL7 Datasheet - Page 9

• Manufacturer Part Number: AD1580BRTZ-REEL7
• Description: IC V-REF 1.225V SOT-23
• Manufacturer: Analog Devices Inc

Specifications of AD1580BRTZ-REEL7

• Temperature Coefficient: 50ppm/°C
• Reference Type: Shunt
• Voltage - Output: 1.225V
• Tolerance: ±0.1%
• Number Of Channels: 1
• Current - Cathode: 50µA
• Current - Output: 10mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-3, TO-236-3, Micro3™, SSD3, SST3
• Topology: Shunt
• Reference Voltage: 1.225V
• Reference Voltage Tolerance: 1mV
• Voltage Reference Case Style: SOT-23
• No. Of Pins: 3
• Fixed / Adjust / Prog: Precision
• Output Voltage (max): 1.225V
• Reference Voltage Accuracy (max): 0.1
• Load Regulation: 6mV
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 3
• Package Type: SOT-23
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Current - Quiescent: -
• Lead Free Status / Rohs Status: Compliant
• Other names: AD1580BRTZ-REEL7TR

TRANSIENT RESPONSE
Many ADC and DAC converters present transient current
loads to the reference. Poor reference response can degrade
the converter’s performance.
Figure 22 displays both the coarse and fine settling characteristics
of the device to load transients of ±50 μA.
Figure 22a shows the settling characteristics of the device for
an increased reverse current of 50 μA. Figure 22b shows the
response when the reverse current is decreased by 50 μA.
The transients settle to 1 mV in about 3 μs.
Attempts to drive a large capacitive load (in excess of 1000 pF) may
result in ringing, as shown in the step response (see Figure 23).
This is due to the additional poles formed by the load capacit-
ance and the output impedance of the reference. A recommended
method of driving capacitive loads of this magnitude is shown
in Figure 20. A resistor isolates the capacitive load from the
output stage, while the capacitor provides a single-pole low-pass
filter and lowers the output noise.
1.8V
2.0V
Figure 23. Transient Response with Capacitive Load
20mV/DIV
20mV/DIV
10mV/DIV
Figure 22. Transient Settling
1mV/DIV
1mV/DIV
V
I
I
IN
R
R
= 100µA + 50µA STEP
= 100µA – 50µA STEP
50µs/DIV
1µs/DIV
C
L
= 0.01µF
(a)
(b)
Rev. D | Page 9 of 12
PRECISION MICROPOWER LOW DROPOUT
REFERENCE
The circuit in Figure 24 provides an ideal solution for making
a stable voltage reference with low standby power consumption,
low input/output dropout capability, and minimum noise output.
The amplifier both buffers and optionally scales up the AD1580
output voltage, V
1 mA of load current. A one-pole filter connected between the
AD1580 and the OP193 input can be used to achieve low output
noise. The nominal quiescent power consumption is 200 μW.
3V
USING THE AD1580 WITH 3 V DATA CONVERTERS
The AD1580 low output drift (50 ppm/°C) and compact submi-
niature SOT-23 package make it ideally suited for today’s high
performance converters in space critical applications.
One family of ADCs for which the AD1580 is well suited is the
AD7714-3 and AD7715-3. The AD7714/AD7715 are charge-
balancing (∑-Δ) ADCs with on-chip digital filtering intended for
the measurement of wide dynamic range, low frequency signals
such as those representing chemical, physical, or biological
processes. Figure 25 shows the AD1580 connected to the
AD7714-3/AD7715-3 for 3 V operation.
AD1580
AD1580
34.8kΩ
34.8kΩ
Figure 25. Reference Circuit for the AD7714-3 and AD7715-3
3V
205Ω
Figure 24. Micropower Buffered Reference
REFIN(+)
REFIN(–)
R
. Output voltages as high as 2.1 V can supply
4.7µF
SWITCHING
FREQUENCY DEPENDS
ON
R3
f
CLKIN
(3pF TO 8pF)
5kΩ (TYP)
R2
AD7714-3 AND AD7715–3
R
OP193
SW
C
REF
V
OR
V
OUT
OUT
IMPEDANCE
HIGH
>1GΩ
= +1.225V
= +1.225 (1 + R2/R3)
AD1580