cat3636 Catalyst Semiconductor, cat3636 Datasheet - Page 10

• Manufacturer Part Number: cat3636
• Description: 6-channel Quad-modetm Fractional Led Driver In Tqfn3x3
• Manufacturer: Catalyst Semiconductor

CAT3636
REGISTER CONFIGURATION AND PROGRAMMING
Table 1. Register Address and Data
Register REG1 allows to set the mode and select the
pairs of LEDs to be turned on. A low LED current
mode exists to allow for very low current operation
under 4mA per channel. If IMODE equals 1, the high
current range is selected up to 32mA. If IMODE is set
to 0, all currents are divided by 8. Each bank of LEDs
(A, B or C) can be turned on independently by setting
the respective bit ENA, ENB, ENC to 1, as shown in
Table 2. For example, to enable all 6 LEDs in low
current mode, REG1 is programmned to 0111 binary
(9 data pulses).
Table 2. REG1 Register Setting
Register REG2 allows to set the same current for all 6
channels. REG3, REG4, REG5 allow to set the
current respectively in banks A, B and C. The three
Doc. No. MD-5020 Rev. D
Pulses
Data
10
11
12
13
14
15
16
Register
0
1
2
3
4
5
6
7
8
9
REG1
REG2
REG3
REG4
REG5
REG6
(binary)
REG1
Value
0000
1111
1110
1101
1100
1011
1010
1001
1000
0111
0110
0101
0100
0011
0010
0001
0000
Address
Pulses
IMODE
1
2
3
4
5
6
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
ENA ENB ENC
On
On
On
On
On
On
On
On
Bank Enable
-
-
-
-
-
-
-
-
-
Bank Enable and IMODE
Bank C Current Setting
Bank A Current Setting
Bank B Current Setting
Global Current Setting
On
On
On
On
On
On
On
On
-
-
-
-
-
-
-
-
-
Return Lockout
Description
On
On
On
On
On
On
On
On
-
-
-
-
-
-
-
-
-
10
banks can be programmed with independent current
values.
Table 3. REG2-5 Current Setting Registers
REG6 contains the return lockout (RTLKO) bit. This
stops the charge pump returning to 1x mode. One
pulse sets it to 1. Two pulses or no pulses set RTLKO
to 0. When RTLKO is set to 1, the charge pump
cannot automatically return to 1x mode when in one of
the charge pump modes. The device can however
move from 1x to 1.33x to 1.5x to 2x if the input voltage
is not sufficient to drive the programmed LED
currents.
REG6 also triggers a charge pump reset as soon as it
is addressed. This forces the charge pump to start
Pulses
Bits
Data
4
4
4
4
4
1
10
11
12
13
14
15
16
0
1
2
3
4
5
6
7
8
9
IMODE
(binary)
Bit 3
REGx
Value
0000
1111
1110
1101
1100
1011
1010
1001
1000
0111
0110
0101
0100
0011
0010
0001
0000
See Table 3 for values
LED Current
Bit 2
ENA
IMODE = 0
DATA Pattern
3.75mA
3.25mA
2.75mA
2.25mA
1.75mA
1.25mA
0.75mA
0.25mA
Characteristics subject to change without notice
1.5mA
0.5mA
0.0mA
0.0mA
3.5mA
2.5mA
3mA
2mA
1mA
Bit 1
ENB
© Catalyst Semiconductor, Inc.
LED Current
IMODE = 1
32mA
30mA
28mA
26mA
24mA
22mA
20mA
18mA
16mA
14mA
12mA
10mA
2mA
8mA
6mA
4mA
2mA
RTLKO
Bit 0
ENC