
CAT3636
Doc. No. 5020 Rev. C
10
2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
REGISTER CONFIGURATION AND PROGRAMMING
Table 1. Register Address and Data
DATA Pattern
Bit 2
ENA
Register
Address
Pulses
1
2
3
4
5
6
Description
Bits
Bit 3
IMODE
Bit 1
ENB
Bit 0
ENC
REG1
REG2
REG3
REG4
REG5
REG6
Bank Enable and IMODE
Global Current Setting
Bank A Current Setting
Bank B Current Setting
Bank C Current Setting
Return Lockout
4
4
4
4
4
1
See Table 3 for values
RTLKO
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
REG1
Value
(binary)
0
0000
1
1111
2
1110
3
1101
4
1100
5
1011
6
1010
7
1001
8
1000
9
0111
10
0110
11
0101
12
0100
13
0011
14
0010
15
0001
16
0000
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
Bank Enable
Data
Pulses
IMODE
ENA ENB ENC
-
-
On
On
On
On
On
-
On
-
-
On
-
On
-
-
-
-
On
On
On
On
On
-
On
-
-
On
-
On
-
-
-
-
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
-
On
-
On
-
On
-
On
-
On
-
On
-
On
-
On
-
banks can be programmed with independent current
values.
Table 3. REG2-5 Current Setting Registers
REGx
Value
(binary)
0
0000
1
1111
2
1110
3
1101
4
1100
5
1011
6
1010
7
1001
8
1000
9
0111
10
0110
11
0101
12
0100
13
0011
14
0010
15
0001
16
0000
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.
Data
Pulses
LED Current
IMODE = 0
LED Current
IMODE = 1
0.0mA
3.75mA
3.5mA
3.25mA
3mA
2.75mA
2.5mA
2.25mA
2mA
1.75mA
1.5mA
1.25mA
1mA
0.75mA
0.5mA
0.25mA
0.0mA
2mA
32mA
30mA
28mA
26mA
24mA
22mA
20mA
18mA
16mA
14mA
12mA
10mA
8mA
6mA
4mA
2mA
REG6 also triggers a charge pump reset as soon as it
is addressed. This forces the charge pump to start