CS

+

-

CSG

CS

AMPLIFIER

+

+

-

FB

COMP

SS

0.8 V

GM ERROR

AMPLIFIER

VISNS

VOSNS

SLOPE

SLOPE

COMP

BUCK-BOOST CONTROLLER

LOGIC

VILIM

RT/SYNC

DITH

OSC/SYNC

CLK

ILIMIT

COMPARATOR

PWM

COMPARATOR

VCC

VCC

BOOT1

HDRV1

SW1

LDRV1

BOOT2

HDRV2

SW2

LDRV2

CCM/DCM

&

HICCUP CURRENT

LIMIT

MODE

A=5

AGND

PGND

EN/UVLO

1.23 V

+

-

ISNS(+)

ISNS(-)

45 mV

+

-

SS

CONSTANT

CURRENT LOOP

VIN

VCC

EN & BIAS

LOGIC

THERMAL

SHUTDOWN

CLK

BIAS

+

-

+

-

+

-

+

-

+

-

+

-

FB

0.88 V

0.72 V

0.86 V

PGOOD

OV

1.2 V

1 mA/V

5 µA

0.7 V

+

-

OPERATING

STANDBY

3.5 µA

1.5 µA

1.6 V

3.3 V

Copyright © 2016, Texas Instruments Incorporated

13

LM5175

www.ti.com

SNVSA37A – OCTOBER 2015 – REVISED MAY 2016

Product Folder Links: LM5175

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Copyright © 2015–2016, Texas Instruments Incorporated

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 Fixed Frequency Valley/Peak Current Mode Control with Slope Compensation

The LM5175 implements a fixed frequency current mode control of both the buck and boost switches. The output

voltage, scaled down by the feedback resistor divider, appears at the FB pin and is compared to the internal

reference (VREF) by an internal error amplifier. The error amplifier produces an error voltage by driving the COMP

pin. An adaptive slope compensation signal based on VIN, VOUT, and the capacitor at the SLOPE pin is added to

the current sense signal measured across the CS and CSG pins. The result is compared to the COMP error

voltage by the PWM comparator.