LP3936 Datasheet, PDF (19/20 Pages) National Semiconductor (TI) – Lighting Management System for Six White LEDs and One RGB or FLASH LED

Recommended External Components (Continued)
List of Recommended External Components
Symbol
Symbol Explanation
C_VDD1
C_VDD2
C_OUT
C_IN
C_VDDIO
C_VDDA
RT
V_DD1 bypass capacitor
V_DD2 bypass capacitor
Output capacitor from FB to GND
Input capacitor from Battery Voltage to GND
V_DDIO bypass capacitor
Internal LDO output capacitor, between V_DDA and GND
Oscillator Frequency Bias Resistor
RDO
DO output pull-up resistor
C_VREF
L_BOOST
D_OUT
RGB
Reference Voltage Capacitor, between V_REF and GND
Boost converter inductor
Rectifying Diode, V_F @ Maxload
RGB LED
R_R, R_G, R_B Current Limit Resistors
LEDs
White LEDs
Value
1
1
10
10
1
1
82
100
100
10
0.3
Unit
Type
µF Ceramic, X7R
µF Ceramic, X7R
µF Ceramic, X7R/Y5V
µF Ceramic, X7R/Y5V
µF Ceramic, X7R
µF Ceramic, X7R
kΩ 1% (Note 16)
kΩ
nF Ceramic, X7R
µH
Shielded, Low ESR, I_SAT A1A
V
Schottky Diode
User Defined
(See Application Note AN-1293 for resistor size calculation)
Note 16: Resistor RT tolerance change will change the timing accuracy of the RGB block. Also the boost converter switching frequency will be affected.
Control Registers
All user accessible control registers and register bits are shown in the following table.
ADDR
SETUP
D7
D6
D5
D4
D3
D2
D1
D0
00H Control register rgb_pwm rgb_start cycle[1] cycle[0]
rsw
gsw
bsw
pfm_mode
01H
ron
ron[6] ron[5]
ron[4]
ron[3]
ron[2]
ron[1]
ron[0]
02H
roff
roff[6] roff[5]
roff[4]
roff[3]
roff[2]
roff[1]
roff[0]
03H
gon
gon[6] gon[5]
gon[4]
gon[3]
gon[2]
gon[1]
gon[0]
04H
goff
goff[6] goff[5]
goff[4]
goff[3]
goff[2]
goff[1]
goff[0]
05H
bon
bon[6] bon[5]
bon[4]
bon[3]
bon[2]
bon[1]
bon[0]
06H
boff
boff[6] boff[5]
boff[4]
boff[3]
boff[2]
boff[1]
boff[0]
07H rslope, rduty rslope[3] rslope[2] rslope[1] rslope[0]
rduty[3]
rduty[2]
rduty[1]
rduty[0]
08H gslope, gduty gslope[3] gslope[2] gslope[1] gslope[0]
gduty[3]
gduty[2]
gduty[1]
gduty[0]
09H bslope, bduty bslope[3] bslope[2] bslope[1] bslope[0]
bduty[3]
bduty[2]
bduty[1]
bduty[0]]
0AH wled current 1 wled1[7] wled1[6] wled1[5] wled1[4]
wled1[3]
wled1[2]
wled1[1]
wled1[0]
0BH
enables
overflow nstby en_boost en_flash en_ambave en_ambadc en_4led
en_2led
0CH Amb. Light data ain[7] ain[6] ain[5]
ain[4]
ain[3]
ain[2]
ain[1]
ain[0]
0DH boost output boost[7] boost[6] boost[5] boost[4]
boost[3]
boost[2]
boost[1]
boost[0]
2AH wled current 2 wled2[7] wled2[6] wled2[5] wled2[4]
wled2[3]
wled2[2]
wled2[1]
wled2[0]
2BH ext pwm enable
en_redpwm en_greenpwm en_bluepwm en_4ledpwm en_2ledpwm
Default value of each register is 0000 0000 except the following
— boost output default is 0000 0111 = 07h (4.55V).
— enables default is x010 0000 = 20h (boost enabled)
— ext_pwm_enable default is 0001 1100 = 1Ch (RGB_EN control enabled for color outputs)
Register 0Ch all bits (ain[7:0]) and bit D7 in register 0Bh (overflow) are read only. All other bits are read-write.
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