REF193 AD [Analog Devices], REF193 Datasheet - Page 17

• Manufacturer Part Number: REF193
• Description: Precision Micropower, Low Dropout Voltage References
• Manufacturer: AD [Analog Devices]

APPLICATIONS SECTION
Output Short Circuit Behavior
The REF19x family of devices is totally protected from damage
due to accidental output shorts to GND or to V+. In the event
of an accidental short circuit condition, the reference device will
shut down and limit its supply current to 40 mA.
Device Power Dissipation Considerations
The REF19x family of references is capable of delivering load
currents to 30 mA with an input voltage that ranges from 3.3 V
to 15 V. When these devices are used in applications with large
input voltages, care should be exercised to avoid exceeding
these devices’ maximum internal power dissipation. Exceeding
the published specifications for maximum power dissipation or
junction temperature could result in premature device failure.
The following formula should be used to calculate a device’s
maximum junction temperature or dissipation:
In this equation, T
tures, respectively, P
the device package thermal resistance.
REV. E
100
0%
TPC 12. Line Transient Response
90
10
Figure 1. Simplified Schematic
200mV
J
5V
and T
D
is the device power dissipation, and θ
A
P
are the junction and ambient tempera-
D
=
T – T
J
θ
J
A
A
+V
V
GND
SLEEP (SHUTDOWN)
OUT
200 s
JA
is
–17–
Output Voltage Bypassing
For stable operation, low dropout voltage regulators and refer-
ences generally require a bypass capacitor connected from their
V
references is capable of stable operation with capacitive loads
exceeding 100 µF, a 1 µF capacitor is sufficient to guarantee rated
performance. The addition of a 0.1 µF ceramic capacitor in parallel
with the bypass capacitor will improve load current transient
performance. For best line voltage transient performance, it is
recommended that the voltage inputs of these devices be bypassed
with a 10 µF electrolytic capacitor in parallel with a 0.1 µF
ceramic capacitor.
Sleep Mode Operation
All REF19x devices include a sleep capability that is TTL/CMOS
level compatible. Internally, a pull-up current source to V
connected at the SLEEP pin. This permits the SLEEP pin to be
driven from an open collector/drain driver. A logic LOW or a 0 V
condition on the SLEEP pin is required to turn the output stage
OFF. During sleep, the output of the references becomes a high
impedance state where its potential would then be determined
by external circuitry. If the sleep feature is not used, it is recom-
mended that the SLEEP pin be connected to V
Basic Voltage Reference Connections
The circuit in Figure 2 illustrates the basic configuration for the
REF19x family of references. Note the 10 µF/0.1 µF bypass net-
work on the input and the 1 µF/0.1 µF bypass network on the
output. It is recommended that no connections be made to Pins 1,
5, 7, and 8. If the sleep feature is not required, Pin 3 should be
connected to V
OUT
Figure 2. Basic Voltage Reference Configuration
pins to their GND pins. Although the REF19x family of
10 F
35
30
25
20
15
10
TPC 13. Dropout Voltage vs. Load Current
5
0
0
0.1
IN
0.1 F
.
0.2
V
SLEEP
IN
REF195 DROPOUT VOLTAGE – V
NC
0.3
NC = NO CONNECT
1
3
4
2
REF19x
0.4
0.5
REF19x Series
8
7
6
5
NC
NC
NC
0.6
0.7
OUTPUT
TANT
1 F
IN
(Pin 2).
0.8
0.1 F
0.9
IN
is