AAT3151B_08 ANALOGICTECH [Advanced Analogic Technologies], AAT3151B_08 Datasheet - Page 9

• Manufacturer Part Number: AAT3151B_08
• Description: High Efficiency 1X/1.5X Charge Pump For White LED Applications
• Manufacturer: ANALOGICTECH [Advanced Analogic Technologies]

AS
1. The device defaults to the 20mA Max scale. Use the Max Current Register to change the Max Scale.
2. There is an additional Low Current mode with currents down to 50μA. See the Low Current Register Settings section.
AS
The AS
sible combinations of current levels and LED channel
states.
AS
SET pin to address and load the registers.
latches data or address after the EN/SET pin has been
3151B.2008.02.1.1
ChargePump
2
Data
Cwire relies on the number of rising edges of the EN/
2
2
10
11
12
13
14
15
16
Cwire Serial Interface Timing
Cwire Serial Interface
1
2
3
4
5
6
7
8
9
Table 1: Constant Current Programming
2
Cwire single wire interface is used to set the pos-
20mA Max
I
OUT
20.0
17.8
15.9
14.3
12.7
11.1
10.2
8.9
7.9
7.0
6.3
5.7
5.1
4.4
4.1
0.0
(mA)
TM
Levels (mA)
1
Data Reg 1
Address
EN/SET
High Efficiency 1X/1.5X Charge Pump For White LED Applications
30mA Max
I
OUT
30.0
26.7
23.8
21.4
19.0
16.7
15.2
13.3
11.9
10.5
9.5
8.6
7.6
6.7
6.2
0.0
2
(mA)
.
1
2
15mA Max
I
OUT
w w w . a n a l o g i c t e c h . c o m
AS
15.0
13.3
11.9
10.7
9.5
8.3
7.6
6.7
6.0
5.2
4.8
4.3
3.8
3.3
3.1
0.0
Address
T
(mA)
LO
2
17
Cwire
1
T
HI
18
T
LAT
held high for time T
by the number of EN/SET rising edges. Since the data
registers are 4 bits each, the differentiating number of
pulses is 24 or 16, so that Address 1 is signified by 17
rising edges, Address 2 by 18 rising edges, and so forth.
Data is set to any number of rising edges between 1 and
including 16. A typical write protocol is a burst of EN/
SET rising edges, signifying a particular address, fol-
lowed by a pause with EN/SET held high for the T
timeout period, a burst of rising edges signifying data,
and a T
address is set, then multiple writes to the corresponding
data register are allowed.
When EN/SET is held low for an amount of time greater
than T
draws less than 1μA from the supply. Address 1 is the
default address on the first rising edge after the
AAT3151B has been disabled. Whenever shutdown mode
is entered, all registers are reset to 1.
AS
A number of addresses are available to control all of the
part’s functionality. Use Address 1 to program all four
LED channels to any one of 16 possible settings that
depend on the Max Current scale setting. Use Address 4
to program the Max Current register, which sets the Max
Current scale.
register. The Low Current register controls the highly
efficient Low Current mode.
1
2
Cwire Addressing
1
OFF
LAT
, the AAT3151B enters shutdown mode and
2 . . .
timeout for the data registers.
Data
Address 5 programs the Low Current
n <= 16
2
LAT
PRODUCT DATASHEET
. Address or data is differentiated
T
LAT
AAT3151B
n
Once an
LAT
9