REF198FSZ Analog Devices Inc, REF198FSZ Datasheet - Page 21

• Manufacturer Part Number: REF198FSZ
• Description: IC MCRPWR LDO V-REF 4.096V 8SOIC
• Manufacturer: Analog Devices Inc
• Series: REF19r

Specifications of REF198FSZ

• Temperature Coefficient: 10ppm/°C
• Reference Type: Series
• Voltage - Output: 4.096V
• Tolerance: ±5mV
• Voltage - Input: 3 ~ 15 V
• Number Of Channels: 1
• Current - Quiescent: 45µA
• Current - Output: 30mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Topology: Series
• Input Voltage: 4.5V To 15V
• Reference Voltage: 4.096V
• Reference Voltage Tolerance: 2mV
• Voltage Reference Case Style: SOIC
• No. Of Pins: 8
• Fixed / Adjust / Prog: Precision
• Output Voltage (max): 4.096V
• Reference Voltage Accuracy (max): 2
• Line Regulation: 8ppm/V
• Load Regulation: 8ppm/mA
• Input Voltage (max): 18V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC N
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Cathode: -
• Lead Free Status / Rohs Status: Compliant

SOLDER HEAT EFFECT
The mechanical stress and heat effect of soldering a part to a
PCB can cause output voltage of a reference to shift in value.
The output voltage of REF195 shifts after the part undergoes the
extreme heat of a lead-free soldering profile, like the one shown
in Figure 23. The materials that make up a semiconductor device
and its package have different rates of expansion and contraction.
The stress on the dice has changed position, causing shift on the
output voltage, after exposed to extreme soldering temperatures.
This shift is similar but more severe than thermal hysteresis.
Typical result of soldering temperature effect on REF19x output
value shift is shown in Figure 24. It shows the output shift due
to soldering and does not include mechanical stress.
6
5
4
3
2
1
0
Figure 24. Output Shift due to Solder Heat Effect
SHIFT DUE TO SOLDER HEAT EFFECT (%)
T
T
25
P
L
T
MAXIMUM RAMP DOWN RATE = 6°C/s
T
SMAX
SMIN
MAXIMUM RAMP UP RATE = 3°C/s
SUPPLIER
SUPPLIER
T
P
PREHEAT AREA
≥ T
C
Figure 23. Classification Profile (Not to Scale)
TIME 25°C TO PEAK
t
t
S
P
Rev. K | Page 21 of 28
T
C
TIME
= –5°C
T
C
CURRENT-BOOSTED REFERENCES WITH CURRENT
LIMITING
Whereas the 30 mA rated output current of the REF19x series is
higher than is typical of other reference ICs, it can be boosted to
higher levels, if desired, with the addition of a simple external
PNP transistor, as shown in Figure 25. Full-time current limiting is
used to protect the pass transistor against shorts.
(SEE TEXT)
COMMON
In this circuit, the power supply current of reference U1 flowing
through R1 to R2 develops a base drive for Q1, whose collector
provides the bulk of the output current. With a typical gain of 100
in Q1 for 100 mA to 200 mA loads, U1 is never required to furnish
more than a few mA, so this factor minimizes temperature-related
drift. Short-circuit protection is provided by Q2, which clamps
the drive to Q1 at about 300 mA of load current, with values as
shown in Figure 25. With this separation of control and power
functions, dc stability is optimum, allowing most advantageous
use of premium grade REF19x devices for U1. Of course, load
V
+V
C
TO 9V
V
S
100µF
S
= 6V
25V
C2
t
Figure 25. Boosted 3.3 V Referenced with Current Limiting
L
+
1N4148
(SEE TEXT
ON SLEEP)
2N3906
t
T
P
D1
USER
P
≤ T
Q2
USER
C
3
2Ω
R4
t
P
(SEE TABLE)
REF196
T
C
U1
2
4
= –5°C
R1
1kΩ
R2
1.5kΩ
1.82kΩ
(SEE TEXT)
6
TIP32A
R3
Q1
(TANTALUM)
C3
0.1µF
10µF/25V
S
C1
S
F
REF19x Series
F
+
U1
REF192
REF193
REF196
REF194
REF195
R1
+V
3.3V
@ 150mA
V
COMMON
OUTPUT TABLE
OUT
OUT
V
2.5
3.0
3.3
4.5
5.0
OUT
(V)