AAT3171 View Datasheet(PDF) - Analog Technology Inc

Part Name

Description

Manufacturer

AAT3171

High Current, High Efficiency Charge Pump with Auto-Timer

Analog Technology Inc 

AAT3171

High Current, High Efficiency

Charge Pump with Auto-Timer

EN

ENFL

Mode

0

0

Off

0

1

Off

1

0

Flash

1

1

Torch

Table 2: Flash/Torch Control Modes.

According to I/O port type, the following equations

can be used to calculate appropriate resistor values.

For an open-drain NMOS I/O port output configu-

ration, the line is pulled low to GND or left floating,

according to state. To calculate the appropriate R1

and R2 resistor values, first calculate the R1 resis-

tor value needed for the desired torch level LED

current:

600mA · 187kΩ

R1 = ILED (torch)

Next, choose R2 based on the desired flash level

LED current:

R2

=

R1

·

R1 · 600mA · 187kΩ

ILED (flash) - 600mA · 187kΩ

The current and resistance values used in the equa-

tions come from the conditions placed on the IDX

parameter of the Electrical Characteristics table.

2.7V

to 5.5V

C1

C2

1µF

1µF

C1+

CIN

4.7µF

C1- C2+

C2+

VOUT

AAT3171

EN

ENCT

CT

EN/SET

CT

GND

F1

RSET

COUT

2.2µF

Flash

LED

R2

R1

ENFL

Figure 3: Flash/Torch Control Using the RSET Pin.

3171.2007.03.1.1

11

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