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ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - LDO voltage regulator Positivbe, adjustable TO 220 5
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DETAILED DESCRIPTION
Pin Functions
Enable (EN)
Feedback (FB)
Input Voltage (IN)
Output Voltage (OUTPUT)
APPLICATION INFORMATION
Programming the TPS75801 Adjustable LDO Regulator
V
O
+ V
REF
ǒ
1)
R1
R2
Ǔ
(1)
R1 +
ǒ
V
O
V
REF
*1
Ǔ
R2
(2)
TPS75801 , , TPS758A01
TPS75815 , TPS75818
TPS75825 , TPS75833
SLVS330F – JUNE 2001 – REVISED APRIL 2007
The TPS758xx family includes four fixed-output voltage regulators (1.5V, 1.8V, 2.5V, and 3.3V), and an
adjustable regulator, the TPS75801 (adjustable from 1.22V to 5V). The bandgap voltage is typically 1.22V.
The EN terminal is an input which enables or shuts down the device. If EN is a low voltage level (< 0.7V), the
device will be in shutdown or sleep mode. When EN goes to a high voltage level (> 2V), the device will be
enabled.
FB is an input terminal used for the adjustable-output option and must be connected to the output terminal either
directly, in order to generate the minimum output voltage of 1.22V, or through an external feedback resistor
divider for other output voltages. The FB connection should be as short as possible. It is essential to route the
terminal so that it minimizes/avoids noise pickup. Adding RC networks between the FB terminal and V
OUT
to
filter noise is not recommended because it may cause the regulator to oscillate.
The V
IN
terminal is an input to the regulator.
The V
OUTPUT
terminal is an output from the regulator.
The output voltage of the TPS75801 adjustable regulator is programmed using an external resistor divider as
shown in Figure 20 . The output voltage is calculated using:
Where:
V
REF
= 1.224V typ (the internal reference voltage).
Resistors R1 and R2 should be chosen for approximately 40 µ A divider current. Lower value resistors can be
used but offer no inherent advantage and waste more power. Higher values should be avoided as leakage
currents at FB increase the output voltage error. The recommended design procedure is to choose R2 = 30.1k Ω
to set the divider current at 40 µ A and then calculate R1 using:
10
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