ISL97671IRZ Intersil, ISL97671IRZ Datasheet - Page 10

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

Specifications of ISL97671IRZ

• 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: -

Typical Performance Curves
FIGURE 16. LINE REGULATION WITH V
FIGURE 18. LOAD REGULATION WITH I
Theory of Operation
PWM Boost Converter
The current mode PWM boost converter produces the
minimal voltage needed to enable the LED stack with the
highest forward voltage drop to run at the programmed
current. The ISL97671 employs current mode control
boost architecture that has a fast current sense loop and
a slow voltage feedback loop. Such architecture achieves
a fast transient response that is essential for the
notebook backlight application where the power can be a
series of drained batteries or instantly change to an
AC/DC adapter without rendering a noticeably visual
nuisance. The number of LEDs that can be driven by
ISL97671 depends on the type of LED chosen in the
application. The ISL97671 is capable of boosting up to
45V and drive 6 channels of LEDs.
FROM 26V TO 6V FOR 6P12S AT
20mA/CHANNEL
FROM 100% TO 0% PWM DIMMING,
V
IN
= 12V, 6P12S AT 20mA/CHANNEL
10
IN
LED
CHANGE
CHANGE
ISL97671
(Continued)
FIGURE 17. LOAD REGULATION WITH I
Enable
The EN pin is used to enable or disable the ISL97671
operation. It is a high voltage pin that can be tied directly
to V
signal.
OVP and V
The Overvoltage Protection (OVP) pin has a function of
setting the overvoltage trip level as well as limiting the
V
The ISL97671 OVP threshold is set by R
R
V
V
Allowable V
V
OUT
LOWER
OUT
OUT
OUT_OVP
FIGURE 19. ISL97671 SHUTS DOWN AND STOPS
IN
_
regulation range.
can only regulate between 64% and 100% of the
OVP
up to 26.5V if the system lacks of I/O for enable
SWITCHING ~ 30ms AFTER EN GOES LOW
as shown in Equation 1:
such that:
=
OUT
FROM 0% TO 100% PWM DIMMING,
V
1.21V
OUT
IN
= 64% to 100% of V
= 12V, 6P12S AT 20mA/CHANNEL
×
Requirement
(
R
UPPER
+
R
LOWER
OUT
) R
⁄
UPPER
LED
_
LOWER
OVP
CHANGE
and
June 24, 2010
FN7631.0
(EQ. 1)