AAT3151B_08 Datasheet, PDF (9/13 Pages) Advanced Analogic Technologies – High Efficiency 1X/1.5X Charge Pump For White LED Applications

ChargePump^TM
PRODUCT DATASHEET
AAT3151B
High Efficiency 1X/1.5X Charge Pump For White LED Applications
Data
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
20mA Max¹
I_OUT (mA)
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
30mA Max
I_OUT (mA)
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
15mA Max
I_OUT (mA)
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
Table 1: Constant Current Programming
Levels (mA)².
AS²Cwire Serial Interface
The AS²Cwire single wire interface is used to set the pos-
sible combinations of current levels and LED channel
states.
AS²Cwire relies on the number of rising edges of the EN/
SET pin to address and load the registers. AS²Cwire
latches data or address after the EN/SET pin has been
held high for time T_LAT. Address or data is differentiated
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_LAT
timeout period, a burst of rising edges signifying data,
and a T_LAT timeout for the data registers. Once an
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_OFF, the AAT3151B enters shutdown mode and
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.
AS²Cwire Addressing
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. Address 5 programs the Low Current
register. The Low Current register controls the highly
efficient Low Current mode.
AS²Cwire Serial Interface Timing
EN/SET
Address
Address
T _HI
T _LO
T_LAT
1
2
17
18
1
Data
T_LAT
1
2 . . . n <= 16
2
Data Reg 1
1
n
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.
3151B.2008.02.1.1
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