60V Low I, Dual, 2-Phase Synchronous Step-Down DC/DC Controller

The LTC3890 is a high performance dual step-down switching regulator DC/DC controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz. Power loss and noise due to the ESR of the input capacitor are minimized by operating the two controller output stages out-of-phase.

The 50μA no-load quiescent current extends operating run time in battery-powered systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3890 features a precision 0.8V reference and power good output indicators. A wide 4V to 60V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries.

Independent TRACK/SS pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous conduction mode at light loads. For a leaded package version (28-lead Narrow SSOP), see the LTC3890-1 data sheet.

LTC3890

LTC3890-1

LTC3890-2

LTC3890-3

Adjustable Current Limit

Limit Yes

No

Yes

No

CLKOUT/PHASMD for

Multiphase Operation

Yes

No

Yes

No

Number of PGood

Outputs

2

1

2

1

OVP – Bottom Gate

Crowbar

Yes

Yes

No

No

Current Limit Foldback

Yes

Yes

No

No

Light Load Operation

when Synced to External

Clock

Forced Continuous

Forced Continuous

Pulse Skipping

Pulse Skipping

SENSE Pins Common

Mode Range

Common Mode < 0.5V

Requires VFB < 0.65V

Common Mode < 0.5V

Requires VFB < 0.65V

Not Dependant on

VFB. Easy to make a

non-synchronous

Boost or SEPIC

Not Dependant on

VFB. Easy to make a

non-synchronous

Boost or SEPIC

Package

5 × 5 QFN-32

SSOP-28

5 × 5 QFN-32

SSOP-28

Applications

* Automotive Always-On Systems

* Battery Operated Digital Devices

* Distributed DC Power Systems

* Wide VIN Range: 4V to 60V (65V Abs Max)

* Low Operating IQ: 50µA (One Channel On)

* Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V

* RSENSE or DCR Current Sensing

* Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise

* Phase-Lockable Frequency (75kHz to 850kHz)

* Programmable Fixed Frequency (50kHz to 900kHz)

* Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode® Operation at Light Loads

* Selectable Current Limit