P6/21

Rev. C, Sep 2005

ML1565

Step-Up DC-DC Converter

Parameter

Condition

Min

Typ.

Max

Unit

Step-Up Startup-to-Normal

Operating Threshold

Rising or falling edge (Note 4)

2.30

2.60

V

Step-Up Voltage Adjust Range

2.7

5.5

V

FBSU Regulation Voltage

1.225

1.275

V

OUTSU Regulation Voltage

FBSELSU = GND

3.283

3.417

V

FBSU to COMPSU Transconductance

FBSU = COMPSU

80

185

µS

FBSU Input Leakage Current

FBSU = 1.25V

-100

+100

nA

Burst Mode Trip Level

(Note 6)

150

275

mA

Step-Up Maximum Duty Cycle

FBSU = 1V

80

90

%

OUTSU Leakage Current

20

µA

LXSU Leakage Current

20

µA

N-channel

150

Switch On-Resistance

P-channel

250

mΩ

N-Channel Current limit

1.6

2.4

A

Auxiliary DC-DC Controllers

(Aux 1, 2, and 3)

Parameter

Condition

Min

Typ.

Max

Unit

Maximum Duty Cycle

FB_ = 1V

80

90

%

FB_ Regulation Voltage

FB_ = COMP_

1.225

1.275

V

FB_ to COMP_

Transconductance

FB_ = COMP_

80

185

µS

FB_ Input Leakage Current

FB_ = 1.25V

-100

+100

nA

AUX1 Output Regulation Voltage

FBSEL1 = GND. FB1 connected directly to AUX1 output

4.90

5.10

V

Output high

10

DL_ Driver Resistance

Output low

5

Ω

Logic Inputs (ON_, FBSEL)

Parameter

Condition

Min

Typ.

Max

Unit

1.1V < OUTSU < 1.8V (ONSU only)

0.2

Input Low Level

1.8V < OUTSU < 5.5V

0.4

V

1.1V < OUTSU < 1.8V (ONSU only)

-0.2

Input High Level

1.8V < OUTSU < 5.5V

1.6

V

FBSEL = 3.6V, OUTSU = 3.6V

-100

+100

FBSEL_ Input Leakage Current

FBSEL = GND, OUTSU = 3.6V

-100

+100

nA

Note 2:

The IC is powered from the OUTSU output.

Note 3:

Since the part is powered from OUTSU, a Schottky rectifier, connected from the input battery to OUTSU, is required

for low-voltage startup.

Note 4:

The step-up regulator operates in startup mode until this voltage is reached. Do not apply full load current during

startup.

Note 5:

The step-up current limit in startup refers to the LXSU switch current limit, not an output current limit.

Note 6:

The burst mode current threshold is the transition point between fixed-frequency PWM operation and burst mode

operation (where switching rate varies with load). The spec is given in terms of inductor current. In terms of output

current, the burst mode transition varies with input/output voltage ratio and inductor value. For step-up, the transition

output current is approximately 1/3 the inductor current when stepping from 2V to 3.3V. For step-down, the transition

current in terms of output current is approximately 3/4 the inductor current when stepping down from 3.3V to 1.8V.