Datasheet

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Startup Sequence
UDG−04031
EN/SYNC
BP5
VIN5
0.7V
1.0V
VOUT
PGOOD
POR
SSWAIT
SS
Differential Amplifier (U7)
8
7
GSNS
DIFFO
VOUT
+
Differential
Amplifier
TPS40130DBT
9
20 kΩ
20 kΩ
20 kΩ 20 kΩ
UDG−04081
TPS40130
SLUS602B – JUNE 2004 – REVISED SEPTEMBER 2005
FUNCTIONAL DESCRIPTION (continued)
Figure 1 shows a typical start up with the VIN5 and BP5 applied to the controller and then the EN/SYNC being
enabled. Shut down occurs when the VIN5 is removed
Figure 1. Startup and Shutdown Sequence
The unity gain differential amplifier with high bandwidth allows improved regulation at a user-defined point and
eases layout constraints. The output voltage is sensed between the VOUT and GSNS pins. The output voltage
programming divider is connected to the output of the amplifier (DIFFO). The differential amplifier input voltage
must be lower than (V
BP5
- 0.7 V).
If there is no need for a differential amplifer, the differential amplifier can be disabled by connecting the GSNS
pin to the BP5 pin and leaving VOUT and DIFFO open. The voltage programming divider in this case should be
connected directly to the output of the converter.
Figure 2. Differential Amplifier Configuration
Because of the resistor configuration of the differential amplifier, the input impedance must be kept very low or
there will be error in setting the output voltage.
10
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