LT8705 datasheet(36/42 Pages) LINER

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LTC7813

7813f

For more information www.linear.com/LTC7813

Table 3. Summary of Trade-Offs in Choosing the VMID Regulation Voltage in a Cascaded Boost+Buck Regulator

Option

VMID_REG > VOUT_REG and

VMID_REG > VIN_MAX_OP

VIN_MIN_OP < VOUT_REG <

VMID_REG < VIN_MAX_OP

VMID_REG = VIN_MIN_OP and

VOUT_REG = VIN_MAX_OP

(Pass-Through/Wire Mode)

VIN_MIN_OP > VMID_REG >

VOUT_REG

Example for Normal Input Operating

Range of 10V to 16V (VIN_MIN_OP =

10V, VIN_MAX_OP = 16V) with a Full

Range of 2.5V to 38V

VMID_REG =18V

VOUT = VOUT_REG = 12V

VMID_REG = 14V

VOUT = VOUT_REG = 12V

VMID_REG =10V

VOUT_REG = 16V

VOUT = 10V to 16V

VMID_REG =10V

VOUT = VOUT_REG = 5V

Boost Boosting in Normal Operating

Range?

Yes, Over Full Range

Yes, When VIN < VMID_REG

Buck Bucking in Normal Operating

Range?

Yes, Over Full Range

No, in Dropout

Yes, Over Full Range

LTC7813 No Load Quiescent Current in

Burst Mode

34µA

~3mA

34µA

Heavy Load Efficiency

Slightly Lower

High When Not Boosting;

Slightly Lower When

Boosting

Highest

High

Input Ripple

Low

Low When Boosting; Very

Low When Not Boosting;

Some Cycle-Skipping

During Transition

Extremely Low

Very Low

Output Ripple

Low

Extremely Low

Low

EMI in Normal Operating Range

Low

Very Low When Not

Boosting; Low When

Boosting

Extremely Low

Very Low

Example for Normal Operating Range:

VIN_MIN_OP = 10V – VIN_MAX_OP = 16V

VMID_REG =18V

VOUT = VOUT_REG = 12V

VMID_REG =14V

VOUT = VOUT_REG = 12V

VMID_REG =10V

VOUT_REG = 16V

VOUT = 10V to 16V

VMID_REG =10V

VOUT = VOUT_REG = 5V

applicaTions inForMaTion

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