SC604A Datasheet, PDF (6/18 Pages) Semtech Corporation – Low Noise, High Efficiency Regulated White LED Driver

SC604A
POWER MANAGEMENT
Block Diagram
C1+ C1- C2- C2+
8 9 10 11
ILED4
13
ILED3
14
ILED2
15
ILED1
16
VOUT 6
VIN 7
mAhXLife^TM Fractional Charge Pump
[1x, 1.5x, 2x]
Current Brightness Control
Current Sense FETs
and Amplifier(s)
12 GND
250kHz
Oscillator
& Delay Clk
Mode Select
[1x, 1.5x, 2x
Startup, Shutdown]
Ouput Selection
Logic
Current Set Detect
5 ^ISET
1.22V Bandgap
Voltage
EN 1 Schmitt Buffer
Schmitt Buffer
Schmitt Buffer
Schmitt Buffer
2 CTRL0
3 ^CTRL1
4 CTRL2
Table 1 - LED Enable Logic
Control Inputs ⁽¹⁾
Output Status
CTRL2
CTRL1
CTRL0
LED4
LED3
LED2
LED1
0
0
0
OFF
OFF
OFF
ON
0
0
1
OFF
OFF
ON
OFF
0
1
0
OFF
ON
OFF
OFF
0
1
1
ON
OFF
OFF
OFF
1
0
0
OFF
OFF
ON
ON
1
0
1
OFF
ON
ON
ON
1
1
0
ON
ON
ON
ON
1
1
1
OFF
OFF
OFF
OFF
Notes:
(1) The sequencing of Enable and logic state CTRL{2,1,0} = [1, 1, 1] will affect quiescent state current. I_Q = 100µA if Enable transitions high before
CTRL{2,1,0} transitions to [1, 1, 1]. I_Q = 400µA if Enable transitions high after CTRL{2,1,0} transitions to [1, 1, 1]. If Enable = high and CTRL{2,1,0}= [1, 1,
1] is to be used for an extended period of time, it is recommended that Enable = High when change to the [1, 1, 1] state to achieve the lower I_Q level.
 2005 Semtech Corp.
www.semtech.com
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