MAX16805_07 Datasheet, PDF (14/19 Pages) Maxim Integrated Products – EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback

EEPROM-Programmable, High-Voltage, 350mA
LED Drivers with LED Current Foldback
Binning Adjustment Register (0x00)
The Binning Adjustment register is a 4-bit register that
sets the differential regulation voltage reference
between CS+ and CS-. Only the first 4 bits of the data
byte update the Binning Adjustment register. The
remaining 4 bits are ignored. See Table 3. The factory-
default register value is 198mV.
Ramp Peak Register (0x01), MAX16806
The Ramp Peak register is a 3-bit register that sets the
maximum peak value of an internally 200Hz generated
ramp. The ramp signal can be programmed for a peak
value of 1.55V to 2.88V. Only the first 3 bits of the data
byte update the Ramp Peak register. The remaining 5
bits are ignored (see Table 4). The factory-default reg-
ister value is 2.88V.
LED Current Foldback Threshold
(LED_CFT) Register (0x02)
LED_CFT is a 4-bit register that sets the threshold for
the onset of the LED current foldback operation. Only
the first 3 bits of the data byte program the LED_CFT
register. Bit 3, not shown in Table 5, sets the LED cur-
rent foldback range.
The MAX16805/MAX16806 start dimming the LED cur-
rent when the input voltage exceeds the LED current
foldback threshold. For bit 3 = 0, the dimming range is
1.2 times the programmed ramp peak voltage. For bit 3
= 1, the dimming range is 2.4 times the programmed
ramp peak. To disable the LED current foldback feature
of the MAX16805/MAX16806 connect CFT to GND. The
factory-default register value is 16V.
Table 3. Binning Adjustment
REGULATION
VOLTAGE (mV)
BIT 3
103.0
0
109.0
0
115.4
0
121.8
0
128.2
0
134.6
0
141.0
0
147.4
0
153.7
1
160.1
1
166.5
1
173.0
1
179.3
1
185.7
1
192.1
1
198.0
1
BIT 2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
BIT 1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
BIT 0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
HEX
(0x00)
(0x01)
(0x02)
(0x03)
(0x04)
(0x05)
(0x06)
(0x07)
(0x08)
(0x09)
(0x0A)
(0x0B)
(0x0C)
(0x0D)
(0x0E)
(0x0F)
Table 4. Ramp Peak Value
RAMP END
POINT (V)
1.55
1.74
1.93
2.12
2.32
2.51
2.70
2.88
BIT 2
0
0
0
0
1
1
1
1
BIT 1
0
0
1
1
0
0
1
1
BIT 0
0
1
0
1
0
1
0
1
HEX
(0x00)
(0x01)
(0x02)
(0x03)
(0x04)
(0x05)
(0x06)
(0x07)
Table 5. LED Current Foldback Threshold
CURRENT
FOLDBACK
THRESHOLD (V)
16.4
15.7
15.0
14.3
13.5
12.8
12.1
11.4
BIT 2 BIT 1 BIT 0 HEX
0
0
0
(0x00)
0
0
1
(0x01)
0
1
0
(0x02)
0
1
1
(0x03)
1
0
0
(0x04)
1
0
1
(0x05)
1
1
0
(0x06)
1
1
1
(0x07)
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