ADP1653ACPZ-R7 datasheet(14/24 Pages) AD

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ADP1653

Data Sheet

Rev. C | Page 14 of 24

2-BIT LOGIC INTERFACE MODE (INTF = 1)

In 2-bit logic interface mode, the two control pins, CTRL1 and

CTRL0, select whether the part is disabled or operating in indicator

LED mode, torch mode, or flash mode, as outlined in Table 7.

Table 7. 2-Bit Logic Interface Mode Selection

INTF = 1

CTRL1

CTRL0

LED Current

Setting Pin

Default Current

(SETx = H)

Disabled

—

ILED

SETI

ILED = 10 mA

Torch

SETT

HPLED = 125 mA

Flash

SETF

HPLED = 500 mA

The LED current levels for indicator LED mode, torch mode,

and flash mode operation are set with separate external resistors

tied between ground and the SETI, SETT, and SETF pins,

respectively. The resulting reference current into each SETx pin

is equal to 1.22 V/RSETx. The reference current multiplied by a

fixed ratio sets the relevant LED current.

Table 8. Reference Current to LED Current Scaling

INTF = 1

CTRL1

CTRL0

LED Current

Disabled

—

ILED

IREF(SETI) × 400

Torch

IREF(SETT) × 5200

Flash

IREF(SETF) × 20,800

Alternatively, a default internal current setting is used by tying

the SETx pin high. The default current for each mode of operation

approximately equals the current obtained with a 50 kΩ resistor

tied from the SETx pin to ground.

Consequently, the LED current resulting from an external

resistor RSETx is given by the following equation:

SETx

DEFAULT

LED

kΩ

(1)

where IDEFAULT is the LED current resulting from tying the SETx

pin high.

The values of IDEFAULT are given in Table 7 for indicator LED mode

(SETI), torch mode (SETT), and flash mode (SETF) operation.

For accurate LED current settings, the minimum SETx resistor

values should be 25 kΩ (SETI, SETT) or 50 kΩ (SETF).

The flash current can be quickly reduced with an external

logic signal (typically 1.8 V logic) by adding a second external

resistor from the SETF pin to the logic signal. Bringing this

digital input from low to high toggles the flash from normal

to reduced current mode by reducing the reference current

supplied to the ADP1653 via the SETF pin (see the Applications

Information section).

I2C INTERFACE MODE (INTF = 0)

The ADP1653 includes an I2C-compatible serial interface for

control of LED current, as well as for readback of system status

registers. The I2C chip address is 0x60 (0110 0000 (binary) in

write mode). The default value of all four registers is 0x00.

Registers values are reset to the default values when enable is

brought low, or the VDD supply falls below the undervoltage

(UVLO) level.

Figure 26 illustrates the I2C write sequence. The subaddress

content selects which of the four ADP1653 registers is written

to. Figure 27 shows the I2C read sequence. The ADP1653 sends

the data from the register denoted by the subaddress. In this

case, the fault register is read (REG3).

The register definitions are shown in Figure 28. The lowest bit

number (0) represents the least significant bit, and the highest

bit number (7) represents the most significant bit.

SUBADDRESS

CHIP ADDRESS

0 = WRITE

ADP1653 RECEIVES DATA

Figure 26. I2C Write Sequence

SUBADDRESS

CHIP ADDRESS

1 = READ

ADP1653 SENDS DATA

0 = WRITE

Figure 27. I2C Read Sequence

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