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CONFIGURATION SETTINGS
Demonstration circuit SCP-LT3094-EVALZ features the
LT3094, an ultralow noise, ultrahigh power supply
rejection ratio (PSRR) negative low dropout (LDO)
regulator. The board operates over an input range of –3.8V
to –20V, and can deliver up to 500mA output current.
The output of the SCP-LT3094-EVALZ is resistor-program-
mable from –0.8V to –19.5V.
OUTPUT VOLTAGE PROGRAMMING
−V
= 100µA •R3
OUT
Table 2. Resistor Selection Guide for Common Output Voltages
|V
| (V)
R3 (Ω)
OUT
0.8
8.06k
0.9
9.09k
1.0
10.0k
1.2
12.1k
1.5
15.0k
1.8
18.2k
2.0
20.0k
2.5
24.9k
3.0
30.1k
3.5
34.8k
4.0
40.2k
4.5
45.3k
5.0
49.9k
5.5
54.9k
6.0
60.4k
6.5
64.9k
7.0
69.8k
7.5
75.0k
8.0
80.6k
8.5
84.5k
9.0
90.9k
EN/UV PIN CONFIGURATION
The EN/UV pin is tied to the optional SCP Run/Sequence
header P1. To create a harness for this function, use Molex
part 0510650300 with crimp pin 50212-8000.
To use an active run signal, use a 100k resistor for either
pull-up or pull-down resistors R2 and R4, short R8 with
0W, and use the drive signal from connector P1.
DEMO MANUAL SCP-LT3094-EVALZ
V
(V)
R3 (Ω)
OUT
9.5
95.3k
10.0
100k
10.5
105k
11.0
110k
11.5
115k
12.0
121k
12.5
124k
13.0
130k
13.5
133k
14.0
140k
14.5
143k
15.0
150k
15.5
154k
16.0
158k
16.5
165k
17.0
169k
17.5
174k
18.0
182k
18.5
187k
19.0
19.1k
19.5
196k
If precision undervoltage lockout (UVLO) operation is de-
sired, program enable divider R2 and R4 such that:
R4 = 1 0 k − 1 0 0 k, n o min al
⎛
− 1 .2 6 V
⎞
V
IN
TH
R2 = R4 •
⎝ ⎜
⎠ ⎟
1 .2 6 V
TH
The hysteresis threshold on the falling edge is typically
200mV above GND, 215mV below GND, and scales by the
factor:
R4 + R2
V
= 1 3 0 (mV)
HYST
R2
ILIM PIN CONFIGURATION
Resistor R7 programs a current limit according to the
scale factor:
1 5 0 mA(kΩ)
I
=
L IM
R7 (kΩ)
Table 3. ILIM Pin Configuration
I
(mA)
R7 (Ω)
LIMIT
10
15.0k
20
7.50k
25
6.04k
30
4.99k
40
3.74k
50
3.01k
60
2.49k
70
2.15k
75
2.00k
80
1.87k
I
(mA)
R7 (Ω)
LIMIT
90
1.65k
100
1.50k
150
1.00k
200
750
250
604
300
499
350
432
400
374
450
453
500
300
Rev. 0
3
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