8.1 Overview

The TPS7H1101-SP is 3-A, 1.5-V to 7-V LDO linear regulator that uses PMOS pass element configuration.

It uses TI’s proprietary process to achieve low noise, high PSRR combined with high thermal performance in a 16-pin ceramic flatpack package (HKR).

A number of features are incorporated in the design to provide high reliability and system flexibility. Current foldback, current limit, and thermal protection are incorporated in the design to make it viable for harsh environments.

The device also has a current sense monitoring feature. A resistor connected from the current sense (CS) terminal to VIN indicates voltage proportional to the output current. When CS is held high, foldback current limit is enabled. Shorting CS low disables the foldback current limit.

A resistor connected from the programmable current limit (PCL) terminal to ground sets the over current limit activation point. When overcurrent limit activation point is reached, it results in LDO going into current foldback mode. Output current is reduced to approximately 50% of the current limit set point. PCL section provides a detailed description of this feature.

TPS7H1101-SP incorporates thermal protection, which disables the output when the junction temperature rises approximately 185°C, allowing the device to cool. Cycling limits the dissipation of the regulator, protecting it from damage as a result of overheating.

A resistor connected from the CS terminal to VIN indicates voltage proportional to the output load current.

To provide system flexibility for demanding current needs, the LDO can be configured in parallel operation as indicated in Figure 22. Current Sharing section provides detailed parallel operation information.

An enable feature is incorporated in the design allowing the user to enable or disable the LDO. Power Good, an open-drain connection, indicates the status of the output voltage. These provide the customers system flexibility in monitoring and controlling the LDO operation. When using the Enable function, V_IN voltage must be > 3.5 V. For V_IN from 1.5 V to 7 V, TPS7H1101-SP can be disabled using the soft-start (SS) terminal as described in Enable/Disable section.

8.2 Functional Block Diagram

Figure 8. Block Diagram

8.3 Feature Description

8.3.1 Soft Start

Connecting a capacitor from the SS terminal to GND (C_SS) slows down the output voltage ramp rate. The soft-start capacitor charges up to 1.2 V.

Equation 1.

where

• t_ss = Soft-start time
• I_ss = 2.5 µA
• V_FB = V_REF / 2 = 0.605 V

8.3.2 Power Good (PG)

Power Good terminal (9) is an open-drain connection and can be used to sequence multiple LDOs. Figure 9 shows typical connection for V_IN > 3.5 V. The PG terminal will be pulled low until the output voltage reaches 90% of its maximum level. At that point, the PG pin will be pulled up. Since the PG pin is open drain, it can be pulled up to any voltage as long as it does not exceed the absolute max of 7.5 V listed in the Electrical Characteristics table.

Figure 9. Sequencing LDOs with Power Good

NOTE

For PSpice models, WEBENCH, and mini-POL reference design, see the Tools & Software tab.

1. PSpice average model (stability – bode plot)
2. PSpice transient model (switching waveforms)
3. WEBENCH design tool (www.ti.com/product/TPS7H1101-SP/toolssoftware)

8.4 Device Functional Modes

8.4.1 Enable/Disable

For V_IN from 1.5 V to 7 V, TPS7H1101-SP can be disabled using the SS terminal. The minimum soft-start pulldown current is 10 μA, with soft start to ground voltage of 400 mV or lower. External voltage applied to the SS terminal must be limited to 1.2-V maximum. Removing the logic-low condition on soft start enables the device allowing the soft-start capacitor to get charged by the internal current source. Alternatively, for V_IN > 3.5 V, the device can be disabled by pulling the enable terminal to logic low. In all other cases, the enable terminal should be connected to VIN.

Figure 10. Enable/Disable

The circuit shown in Figure 10 highlights the SS terminal 1 along with block diagram of internal circuitry. Circuitry in dashed outline is internal to the IC composed of PMOSFET current mirror. The PMOS current mirror sources current from the positive supply and external circuitry composed of Qext is used to sink current from SS terminal 1. As highlighted in the Electrical Characteristics table, typical ISS = 2.5 μA and max ISS = 3.5 μA for TPS7H1101-SP. If ISS current is exceeded, such as sinking higher current in excess of max ISS, this disables the LDO. See the Electrical Characteristics table for the external sink current from SS terminal necessary to disable the IC. Exceeding maximum external sink current does not damage the device.