L1

4.7

H

m

LQH32CN4R7M11

L

SW

DO

FB

GND

CTRL

PGND

TPS61045

V

=1.8Vto6V

CC

C2

4.7 F

m

D1

ZetexZHZS400

VIN

R1

2.2M

Cff

22pF

15Vto18V

Adjustable/10mA

R2

180kW

C1

100nF

C3

1 F

m

Enable

R3

390k

DACor AnalogVoltage

0V=25V

1.233V=18V

TPS61045

www.ti.com

SLVS440C – JANUARY 2003 – REVISED DECEMBER 2014

8

Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The TPS61045 device is a high-frequency boost converter with digitally-programmable output voltage and true

shutdown. The TPS61045 device operates with an input voltage range of 1.8 to 6 V and generates output

voltages up to 28 V. The device operates in a constant peak current control, which maintains high efficiency over

the entire load current range, and with a typical switching frequency of up to 1 MHz.

8.2 Typical Application

The following section provides a step-by-step design approach for configuring the TPS61045 as a voltage

regulating boost converter, as shown in Figure 12.

8.2.1 Analog Adjusted Output Voltage

Figure 12. Typical Application With Analog Adjusted Output Voltage

8.2.1.1 Design Requirements

Table 3. Design Parameters

PARAMETERS

VALUES

Output voltage

18 V

Input voltage

1.8 to 6 V

Output current

10 mA

8.2.1.2 Detailed Design Procedure

8.2.1.2.1

Inductor Selection, Maximum Load Current

Because the PFM peak current control scheme is inherently stable, the inductor and capacitor value does not

affect the stability of the regulator. The selection of the inductor together with the nominal load current, input, and

output voltage of the application determines the switching frequency of the converter. Depending on the

application, TI recommends inductor values between 2.2 to 47

μH. The maximum inductor value is determined

by the maximum switch on-time of 6

μs (typical). The peak current limit of 375 mA (typical) must be reached

within 6

μs for proper operation.

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