Datasheet
Table Of Contents
- FEATURES
- APPLICATIONS
- DESCRIPTION
- ABSOLUTE MAXIMUM RATINGS
- DISSIPATION RATINGS
- RECOMMENDED OPERATING CONDITIONS
- ELECTRICAL CHARACTERISTICS
- DEVICE INFORMATION
- TYPICAL CHARACTERISTICS
- APPLICATION INFORMATION
- PWM Operations
- Adaptive On-Time Control and PWM Frequency
- Loop Compensation
- Ramp Signal
- Light Load Condition in Auto-Skip Operation
- Out-of-Audio™ Light-Load Operation
- Enable and Soft Start
- VREG5/VREG3 Linear Regulators
- VREG5 Switch Over
- VREG3 Switch Over
- Powergood
- Output Discharge Control
- Low-Side Driver
- High-Side Driver
- Current Protection
- Overvoltage and Undervoltage Protection
- UVLO Protection
- Thermal Shutdown
- External Parts Selection
- Layout Considerations
- Application Circuit
- Revision History
TPS51123
www.ti.com
SLUS890E –DECEMBER 2008–REVISED JANUARY 2013
DEVICE INFORMATION
Table 1. TERMINAL FUNCTIONS TABLE
TERMINAL
I/O DESCRIPTION
NAME NO.
DRVH1 21
O High-side N-channel MOSFET driver outputs. LL referenced drivers.
DRVH2 10
DRVL1 19
O Low-side N-channel MOSFET driver outputs. GND referenced drivers.
DRVL2 12
Master enable input.
EN0 13 I/O Open : LDOs on, and ready to turn both switcher channels.
GND : disable all circuit
Channel 1 and Channel 2 enable input. Pull up to the voltage ranging 3.3-V to 5-V to turn on both
ENC 18 I
switcher channels. Short to ground to shutdown them.
GND 15 – Ground.
LL1 20
I Switch node connections for high-side drivers, current limit and control circuitry.
LL2 11
PGOOD 23 O Powergood window comparator output for channel 1 and 2. (Logical AND)
Selection pin for operation mode:
OOA auto skip : Connect to VREG3 or VREG5
SKIPSEL 14 I
PWM only: Connect to VREF
Auto skip: Connect to GND
TRIP1 1 I/O
OCL trip setting pins. Connect resistor from this pin to GND to set threshold for synchronous R
DS(on)
sense.
TRIP2 6
On-time adjustment pin.
365 kHz/460 kHz setting: connect to VREG5
TONSEL 4 I 300 kHz/375 kHz setting: connect to VREG3
245 kHz/305 kHz setting: connect to VREF
200 kHz/250 kHz setting: connect to GND
VBST1 22
I Supply input for high-side N-channel MOSFET driver (boost terminal).
VBST2 9
VFB1 2
I SMPS feedback inputs. Connect with feedback resistor divider.
VFB2 5
VIN 16 I High voltage power supply input for 5-V/3.3-V LDO.
VO1 24
Output connection to SMPS. These terminals work as fixed voltage inputs and output discharge
I/O
inputs. VO1 and VO2 also work as 5-V and 3.3-V switch over return power input respectively.
VO2 7
2-V reference voltage output. Connect 220-nF to 1-μF ceramic capacitor to Signal GND near the
VREF 3 O
device.
3.3-V power supply output. Connect a 10-μF ceramic capacitor to Power GND near the device. A 1-
VREG3 8 O
μF ceramic capacitor is acceptable when not loaded.
VREG5 17 O 5-V power supply output. Connect a 33-μF ceramic capacitor to Power GND near the device.
Copyright © 2008–2013, Texas Instruments Incorporated Submit Documentation Feedback 7
Product Folder Links: TPS51123