2

DEMO MANUAL DC3126A

Rev. 0

QUICK START PROCEDURE

Demonstration circuit 3126A is easy to set up to evalu-

ate the performance of the LT8686S. Refer to Figure 1

for proper measurement equipment setup and use the

following the procedure.

1. With power off, place the jumpers in the following

positions:

JP1

JP2

JP3

JP4

JP5

JP6

EN/UVLO

EN2

EN3

EN4

BIAS

SYNC/MODE

ON

ON

ON

ON

VOUT1

BURST

2. With the power off, connect the input power supply

to VEMI+ and VEMI–.

3. With the power off, connect the loads from VOUT1,

VOUT2, VOUT3, and VOUT4 to GND.

4. Voltmeters can be placed across the output terminals

to get accurate output voltage measurements.

5. Turn on the power at the input.

NOTE: Make sure that the input voltage does not

exceed 42V.

6. Check for proper output voltages. The output should

be regulated at 5V (±4%), 3.3V (±4%), 1.8V (±4%),

and 1.2V (±4%).

NOTE: If there is no output, temporarily disconnect

the load to ensure that the load is not set too high.

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

VIN_HV

HV Regulators Input Voltage (VIN1/VIN2) Range

6*

12

42

V

VIN_LV

LV Regulators Input Voltage (VIN3/VIN4) Range

3

8**

V

VOUT1

Output1 Voltage

VIN_HV = 12V

4.8

5

5.2

V

VOUT2

Output2 Voltage

VIN_HV = 12V

3.17

3.3

3.43

V

VOUT3

Output3 Voltage

VIN_LV = 5V

1.73

1.8

1.87

V

VOUT4

Output4 Voltage

VIN_LV = 5V

1.15

1.2

1.25

V

IOUT1

Maximum Output1 Current

No Load on Downstream Channel

2

A

IOUT2

Maximum Output2 Current

2

A

IOUT3

Maximum Output3 Current

2

A

IOUT4

Maximum Output4 Current

2

A

fSW

Switching Frequency

1.8

2

2.25

MHz

EFF

Efficiency

VIN_HV = 12V, fSW = 2MHz, VOUT1 = 5V, IOUT1 = 1A

93.3

%

VIN_HV = 12V, fSW = 2MHz, VOUT2 = 3.3V, IOUT2 = 1A

90.8

%

VIN_LV = 5V, fSW = 2MHz, VOUT3 = 1.8V, IOUT3 = 1A

92.1

%

VIN_LV = 5V, fSW = 2MHz, VOUT4 = 1.2V, IOUT4 = 1A

88.6

%

*The operating input voltage range for VIN1 and VIN2 is 3V to 42V. The 6V minimum input voltage spec is limited by the 5V output voltage.

**The operating input voltage range for VIN3 and VIN4 is 3V to 8V. The absolute maximum input voltage for VIN3 and VIN4 is 10V.

PERFORMANCE SUMMARY Specifications are at T

A = 25°C