ZHCSN51J june 2007 – april 2023 TPS74901
PRODUCTION DATA
The TPS74901 offers very low dropout performance, making the device designed for high-current low VIN and low VOUT applications. The low dropout of the TPS74901 allows the device to be used in place of a DC/DC converter and still achieve good efficiencies. This capability provides designers with the power architecture for applications to achieve the smallest, simplest, and lowest-cost solution.
There are two different specifications for dropout voltage with the TPS74901. The first specification (see Figure 8-1) is referred to as VIN dropout and is used when an external bias voltage is applied to achieve low dropout. This specification assumes that VBIAS is at least 3.25 V above VOUT, which is the case for VBIAS when powered by a 5-V rail with 5% tolerance and with VOUT = 1.5 V (3.25 V is a test condition of this device and can be adjusted by referring to Figure 6-6). If VBIAS is higher than VOUT + 3.25 V, VIN dropout is less than specified.
The second specification (shown in Figure 8-2) is referred to as VBIAS dropout and is applied to applications
where IN and BIAS are tied together. This option allows the device to be used in
applications where an auxiliary bias voltage is not available or low dropout is not
required. Dropout is limited by BIAS in these applications because VBIAS
provides the gate drive to the pass transistor; therefore, VBIAS must
be
1.75 V above VOUT. Because of this
usage, IN and BIAS tied together easily consume a huge amount of power. Pay
attention not to exceed the power rating of the device package.