Datasheet

V
OUT
V
REF
- 1 R = R
1 2
V
OUT
R + R
1 2
³ 5 Am, where
Where:
V
OUT
R + R
1 2
³ 5 A, andm
V
OUT
V
REF
- 1R = R
1 2
TPS7A3301
OUT
FB
GND
C
10 F
IN
m
C
1 F
NR/SS
m
R
1
1.24 MW
R
2
105 kW
C
10 nF
FF
C
47 F
OUT
m
IN
EN
NR/SS
V
IN
V
OUT
= 15 V-
TPS7A33
www.ti.com SBVS169C –DECEMBER 2011–REVISED FEBRUARY 2013
THEORY OF OPERATION
GENERAL DESCRIPTION
The TPS7A33 belongs to a family of new-generation linear regulators that use an innovative bipolar process to
achieve ultralow-noise and very high PSRR levels at a wide input voltage and current range. These features,
combined with the external heatsink-capable, high thermal performance TO-220 package, make this device ideal
for high-performance analog applications.
ADJUSTABLE OPERATION
The TPS7A3301 has an output voltage range of –1.182 V to –33 V. The nominal output voltage of the device is
set by two external resistors, as shown in Figure 28.
Figure 28. Adjustable Operation for Maximum AC Performance
R
1
and R
2
can be calculated for any output voltage range using Equation 1. To ensure stability under no load
conditions at V
OUT
> V
REF
, this resistive network must provide a current equal to or greater than 5 μA.
(1)
If greater voltage accuracy is required, take into account the output voltage offset contributions because of the
feedback pin current and use 0.1% tolerance resistors.
Table 1 shows the resistor combination to achieve a few of the most common rails using commercially-available,
0.1%-tolerance resistors to maximize nominal voltage accuracy while abiding to the formula shown in Equation 1:
Table 1. Suggested Resistors for Common Voltage Rails
V
OUT
R
1
R
2
V
OUT
/(R
1
+R
2
) NOMINAL ACCURACY
–1.171 V 0 Ω ∞ 0 μA ±1.5%
–1.8 V 76.8 kΩ 143 kΩ 8.18 μA ±(1.5% + 0.08%)
–3.3 V 200 kΩ 110 kΩ 10.64 μA ±(1.5% + 0.13%)
–5 V 332 kΩ 102 kΩ 11.48 μA ±(1.5% + 0.50%)
–10 V 1.62 MΩ 215 kΩ 5.44 μA ±(1.5% + 0.23%)
–12 V 1.5 MΩ 162 kΩ 7.22 μA ±(1.5% + 0.29%)
–15 V 1.24 MΩ 105 kΩ 11.15 μA ±(1.5% + 0.18%)
–18 V 3.09 MΩ 215 kΩ 5.44 μA ±(1.5% + 0.19%)
–24 V 1.15 MΩ 59 kΩ 19.84 μA ±(1.5% + 0.21%)
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