ISL97691 Datasheet, PDF (1/19 Pages) Intersil Corporation – Adjustable switching frequency from 400kHz to 1.5MHz

2.4V LED Driver with Independent Analog and PWM
Dimming Controls of 2 Backlights for 3D Application
ISL97691
The ISL97691 is Intersil’s highly integrated 4 channel LED driver
for single cell Li-Ion battery operated mobile displays requiring
analog dimming, and for 3D mobile display applications. It drives
four 40mA channels of LEDs up to 26V from an input supply 2.4V
to 5.5V. The ISL97691 will also drive 60mA channels up to 21V at
30% duty for high peak current 3D modes.
The ISL97691 provides 4 channels of current with 2 independent
analog dimming controls and 2 independent PWM dimming
controls. Channels 1 and 2 form one channel group and channels
3 and 4 form the other channel group. Each channel group’s
analog dimming is controlled through 1-Wire communication
with 6-bit resolution and each channel group’s PWM dimming is
controlled by a separate PWM input. This unique setup allows 2D
or 3D application where independent and dynamic channel
control of LED peak current and PWM dimming duty cycle are
possible. The ISL97691 employs adaptive boost architecture that
allows ultra low dimming duty cycle as low as 0.005% at 100Hz
dimming frequency.
The driver features dynamic headroom control that monitors the
highest LED forward voltage string and uses its feedback signal
for the minimum output regulation.
The ISL97691 incorporates extensive protection functions
including string open and short circuit detections, OVP, and OTP.
The switching frequency can be adjusted from 400kHz to 1.5MHz.
The device is offered in a 16 Ld TQFN 3x3mm package and can
operate in ambient temperature from -40°C to +85°C.
Features
• 2.4V Minimum input voltage, no need for higher voltage
supplies
• 4 x 60mA (Note 1) and 4 x 40mA (Note 2) LED current
• 2 Groups of independent analog and pwm current controls
- 1-Wire interfaces for 6-bit analog dimming
- PWM inputs for PWM dimming
- 0.005% Minimum PWM dimming duty cycle at 100Hz
• Low 0.8mA quiescent current
• ±2.5% current matching
• Adjustable switching frequency from 400kHz to 1.5MHz
• Fault protection
- OVP, OTP, channel open/short circuit protections
Applications
• Tablet, notebook PC and smart phone displays LED
backlighting
• Mobile displays for 2D or 3D LED backlighting
NOTES:
1. Not exceeding 30% of the frame rate (1/t_FRAME), with V_IN > 2.7V and
T_A < +55°C.
2. V_IN > 2.7V
I
VIN = 2.7V~5.5V
4.7µF
10Ω
L1
10µH
D1
VOUT = 24.5V, 4 x 60mA*
4.7µF 4.7µF
VIN
1µF
LX
100pF
10
470kΩ
15nF
COMP
OVP
23.7kΩ
12kΩ
ISL97691
2.2nF
1
ISET
17.8kΩ
PGND
0.1
AGND
143kΩ
1-WIRE_1
1-WIRE_2
PWM2
PWM_1
FSW
CH1
CH2
CH3
CH4
*NOT EXCEEDING 30% PWM DUTY
FIGURE 1. TYPICAL APPLICATION CIRCUIT
0.01
0.001
f_PWM: 200Hz
f_PWM: 100Hz
0.0001
0.001
0.01
0.1
1
10
INPUT DIMMING DUTY CYCLE (%)
FIGURE 2. ULTRA LOW PWM DIMMING LINEARITY
February 1, 2013
1
FN7840.1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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