APPLICATION NOTES
BREAKDOWN VOLTAGE
The breakdown voltage of the MSK 110RH can be optimized to
meet the applications circuit requirement and/or adjust for the initial
voltage tolerance. As shown in Figure 1, a 10K potentiometer is
added in parallel with the V+ and V- of the voltage reference with
the potentiometer adjust pin connected to ADJ of the voltage refer-
ence. The output voltage trim range for the circuit is approximately
±5%. Leave the adjust pin unconnected if the adjust feature is not
used.
Figure 3 shows the MSK 110RH configured with the MSK 5977RH
to provide the same accuracy improvement benefits as the circuit
above but require less voltage overhead and it does not require the
load to sink the divider current. This configuration is limited to an
output operating range of 0V to 2.5V. For 2.5V output R1 would be
zero ohms leaving the set pin of the regulator connected directly to
the V+ terminal of the reference; R2 can also be omitted (left open)
in the 2.5V configuration. Select Rs or a current source to maintain
between one and ten milliamps in the reference and supply the re-
sistor divider current under all operating conditions. The resistor
divider current should be 1mA or greater to swamp out the effects
of the set pin current except in the 2.5V (no divider) case. As above,
R1 and R2 tolerance should be 0.1% or better tolerance with low
and/or matching TCR for best accuracy.
FIGURE 1
PRECISION REFERENCE FOR LINEAR REGULA-
TOR
The MSK 110RH provides increased initial accuracy and reduced
drift due to temperature and irradiation to the output accuracy of the
MSK 5976RH, MSK 5977RH and the MSK 5953RH radiation hard-
ened linear regulators. The MSK 5977RH is used in the provided
examples. Refer to the respective data sheets for more specific
information on each device. Figure 2 shows the MSK 110RH con-
figured to set a precision current in a resistor divider network set-
ting the final output voltage of the MSK 5977RH. This configuration
allows the output voltage of the MSK 5977 to be adjusted between
0V and the maximum range of the MSK 5977RH. The current in R1
is equal to the reference voltage divided by R1. The current in R2 is
equal to the current in R1 plus the 10uA nominal set pin current. By
setting the current in R1 to 1mA or greater the accuracy error of the
set pin current is swamped out by the higher accuracy of the MSK
110RH reference. To maintain high accuracy R1 and R2 tolerance
should be 0.1% or better with low and/or matching TCR. This con-
figuration swamps out initial accuracy error, temperature drift, drift
due to irradiation, line regulation and load regulation error of the set
pin current. The MSK 110RH may be biased from Vin, Vcontrol or a
separate source but it must be greater than Vout by 2.5V plus the
drop across R
S
; V
MIN
=V
OUT
+2.5V
REF
+V
RS
. The minimum output
load must sink the minimum load current from the MSK 5977RH
plus the current passing through the MSK 110RH to maintain regu-
lation. The source used to bias the reference must also supply the
divider current set by the reference and the R1.
To maintain high accuracy R1 and R2 tolerance should be 0.1% or
better with low and/or matching TCR
FIGURE 3
TOTAL DOSE RADIATION TEST
PERFORMANCE
Radiation performance curves for TID testing have been generated
for all radiation testing performed by MS Kennedy. These curves
show performance trends throughout the TID test process and are
located in the MSK 110RH radiation test report. The complete radia-
tion test report is available in the RAD HARD PRODUCTS section on
the MSK website.
ADDITIONAL APPLICATION INFORMATION
For additional applications information, please reference Linear Tech-
nology Corporation's® LT1009 and RH1009 data sheets.
To maintain high accuracy R1 and R2 tolerance should be 0.1% or
better with low and/or matching TCR. For clarity, �½ of MSK 110RH
shown.
FIGURE 2
3
PRELIMINARY Rev. - 2/11
MSK [ M.S. KENNEDY CORPORATION ]
