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

The LTC3890-2 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. 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 mode control limits the inductor current during short-circuit conditions. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous conduction mode at light loads. For versions with different and/or additional features, see the LTC3890 family summary, Table 1, in the Pin Functions section of this data sheet.

LTC3890

LTC3890-1

LTC3890-2

LTC3890-3

Adjustable Current 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

5X5 QFN-32

SSOP-28

5X5 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 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