ISL97671IRZ-T Intersil, ISL97671IRZ-T Datasheet - Page 13

• Manufacturer Part Number: ISL97671IRZ-T
• Description: IC LED DVR PWM CTRL 6CH 20QFN
• Manufacturer: Intersil

Specifications of ISL97671IRZ-T

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Automotive, Backlight
• Type - Secondary: RGB, White LED
• Frequency: 600kHz ~ 1.2MHz
• Voltage - Supply: 4.5 V ~ 26.5 V
• Mounting Type: Surface Mount
• Package / Case: 20-VFQFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 40mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -

When EqualPhase = 1, the phase shift evenly spreads the
channels switching across the PWM cycle, depending on
how many channels are enabled, as shown in Figures 22
and 23. Equal phase means there are fixed delays
between channels and such delay can be calculated as
t
t
where (255/N) is rounded down to the nearest integer.
For example, if N = 6, (255/N) = 42, that leads to
t
t
where t
of LED channels. The ISL97671 will detect the numbers
of operating channels automatically.
FIGURE 21. NO DELAY (DEFAULT PHASE SHIFT
FIGURE 22. 6 EQUAL PHASE CHANNELS PHASE SHIFT
D1
D2
D1
D2
PWMI
ILED0
ILED1
ILED2
ILED3
ILED4
ILED5
ILED0
ILED0
ILED1
ILED2
ILED3
ILED4
ILED5
=
=
= t
= t
t
------------------ - x
t
------------------ - x 255
FPWM
FPWM
FPWM
FPWM
255
255
FPWM
60%
t
D1
t
D1
x 42/255
x 45/255
40%
60%
DISABLED)
ILLUSTRATION
⎛
⎝
⎛
⎝
is the sum of t
255
--------- -
t
N
D1
t
ON
⎞
⎠
–
t
D1
t
FPWM
(
N 1
t
D1
40%
–
t
)
D2
⎛
⎝
t
OFF
255
--------- -
13
N
ON
⎞
⎠
⎞
⎠
t
ON
and t
t
FPWM
OFF
. N is the number
t
OFF
(EQ. 13)
(EQ. 14)
ISL97671
FIGURE 23. 4 EQUAL PHASE CHANNELS PHASE SHIFT
The ISL97671 allows the user to program the amount of
phase shift degree in 7-bit resolution, as shown in
Figure 24. To enable programmable phase shifting, the
user must write to the Phase Shift Control register with
EqualPhase = 0 and the desirable phase shift value of
PhaseShift[6:0]. The delay between CH5 and the
repeated CH0 is the rest of the PWM cycle.
Switching Frequency
The default switching frequency is 600kHz but it can be
selected to 600kHz or 1.2MHz if the SMBus/I
communications is used. The switching frequency select
bit is accessible in the SMBus/I
0x08 bit 2.
5V Low Dropout Regulator
A 5V LDO regulator is present at the VDC pin to develop
the necessary low voltage supply, which is used by the
chips internal control circuitry. Because VDC is an LDO
pin, it requires a bypass capacitor of 1µF or more for the
regulation. Low input voltage also allows only lower
output voltage applications only with the maximum
boost ratio defined in “Components Selections” on
page 25. The VDC pin can be used as a coarse reference
with a few mA sourcing capability.
FIGURE 24. PHASE SHIFT WITH 7-BIT PROGRAMMABLE
PWMI
ILED1
ILED2
ILED3
ILED4
ILED1
ILED0
ILED1
ILED2
ILED3
ILED4
ILED5
t
D1
60%
= Fixed Delay with Integer only while the decimal value will be discarded (eg. 63.75=63)
t
PWMin
40%
t
ILLUSTRATION
PD
DELAY
t
PD
t
D1
t
PD
t
ON
t
ON
t
PD
t
D1
60%
(t
t
PWMout
FPWM
t
t
PD
FPWM
t
)
D1
t
OFF
40%
t
D2
t
OFF
2
C Configuration Register
2
C
June 24, 2010
FN7631.0