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MAX1579ETG+

P1-P3P4-P6P7-P9P10-P12P13-P13
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
4 _______________________________________________________________________________________
Note 1: All devices are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: V
D1
is the forward-voltage drop of diode D1 in Figure 3.
Note 3: Time from CTRL going below the Dual-Mode threshold to IC shutdown.
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 3, V
IN
= 3V, CTRL = ONBIAS = IN, T
A
= -40°C to +85°C, typical values are at T
A
= +25°C, unless otherwise noted. Note 1)
PARAMETER CONDITIONS
MIN
TYP
UNITS
N-CHANNEL SWITCH
LX On-Resistance I
LX
= 190mA
0.82
1.5 Ω
T
A
= +25°C
0.01
5
LX Leakage Current V
LX
= 28V, CTRL = GND
T
A
= +85°C 1
µA
LX Current Limit Duty cycle = 90%
500 700 900
mA
Typical Operating Characteristics
(Circuit of Figure 3, V
IN
= 3.6V, I
LED
= 20mA, 4 LEDs, CTRL = IN, T
A
= +25°C, unless otherwise noted.)
50
55
60
65
70
75
80
85
90
0 5 10 15 20 25
LED EFFICIENCY vs. I
LED
MAX1578toc01
LED CURRENT (mA)
EFFICIENCY (%)
2 LEDs
4 LEDs
6 LEDs
8 LEDs
50
55
60
65
70
75
80
85
90
2.5 3.0 3.5 4.0 4.5 5.0 5.5
LED EFFICIENCY vs. V
IN
MAX1578toc02
INPUT VOLTAGE (V)
EFFICIENCY (%)
I
LED
= 2mA
I
LED
= 10mA
I
LED
= 20mA
0
10
5
20
15
25
30
-40 85
LED CURRENT vs. TEMPERATURE
MAX1578toc03
TEMPERATURE (°C)
I
LED
(mA)
10-15 35 60
MAX1579
R
CS
= 13
Ω
MAX1578
R
CS
= 22
Ω
0
5
15
10
20
25
01.00.5 1.5 2.0 2.5
LED CURRENT vs. V
CTRL
MAX1578toc04
CTRL VOLTAGE (V)
I
LED
(mA)
Typical Operating Characteristics (continued)
(Circuit of Figure 3, V
IN
= 3.6V, I
LED
= 20mA, 4 LEDs, CTRL = IN, T
A
= +25°C, unless otherwise noted.)
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
_______________________________________________________________________________________ 5
PWM-DIMMING WAVEFORMS
MAX1578toc08
V
CTRL
I
IN
V
OUT
AC-COUPLED
V
IN
AC-COUPLED
2V/div
50mV/div
20mA/div
20mV/div
40
μ
s/div
0
400
200
800
600
1200
1000
1400
023145
LCD BIAS SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX1578toc09
INPUT VOLTAGE (V)
I
IN
(μA)
V
CTRL
= 0V
LCD BIAS STARTUP SEQUENCE
MAX1578toc10
V
ONBIAS
V
POS
V
NEG
V
MAIN
5V/div
5V/div
10V/div
5V/div
10ms/div
BOOST STARTUP AND
SHUTDOWN WAVEFORMS
MAX1578toc07
V
CTRL
I
IN
V
OUT
V
IN
AC-COUPLED
2V/div
5V/div
0V
100mA/div
20mV/div
4ms/div
0
5
10
15
20
25
0405020 3010 60 70 80 90 100
LED CURRENT vs.
DIRECT-PWM DUTY CYCLE
MAX1578toc05
PWM DUTY CYCLE (%)
I
LED
(mA)
f
PWM
= 200Hz TO 200kHz
BOOST-SWITCHING WAVEFORMS
MAX1578toc06
V
IN
AC-COUPLED
V
LX
V
OUT
AC-COUPLED
20mV/div
10V/div
200mV/div
400ns/div
MAX1578/MAX1579
Complete Bias and White LED Power Supplies
for Small TFT Displays
6 _______________________________________________________________________________________
-5.0
-3.5
-4.0
-4.5
-3.0
-2.5
-2.0
-1.5
-1.0
POS
NEG
-0.5
0
04020 60 80 100
POS AND NEG LOAD REGULATION
MAX1578toc12
LOAD CURRENT (
μ
A)
VOLTAGE DROOP (%)
-0.6
-0.4
-0.5
-0.2
-0.3
-0.1
0
025
MAIN OUTPUT LOAD REGULATION
MAX1578toc11
LOAD CURRENT (mA)
VOLTAGE DROOP (%)
1051520
PIN NAME FUNCTION
1 MAIN
LDO Output and the POS and NEG Charge-Pump Inputs. V
MAIN
is regulated to 5V. Bypass to GND
with a 1µF capacitor. Output is internally discharged with a 1kΩ resistor when V
ONBIAS
= 0V.
2 CU1 POS Charge-Pump Capacitor Connection 1. Connect a 1µF capacitor between CU1 and PMP.
3 CU2 POS Charge-Pump Capacitor Connection 2. Connect a 1µF capacitor between CU2 and PMPB.
4 CU3 POS Charge-Pump Capacitor Connection 3. Connect a 1µF capacitor between CU3 and GND.
5 POS
Output of Positive (3x) Charge Pump. Bypass POS to GND with a 1µF capacitor. POS is internally
discharged with a 3kΩ resistor when V
ONBIAS
= 0V.
6PMP
Charge-Pump Capacitor Connection. Connect a 1µF capacitor between PMP and CU1 and another
1µF capacitor between PMP and CD1.
7 PMPB
Charge-Pump Capacitor Connection. Connect a 1µF capacitor between PMPB and CU2 and another
1µF capacitor between PMPB and CD2. PMPB is 180° out of phase with PMP.
8 CD1
NEG Charge-Pump Capacitor Connection 1. Connect a 1µF capacitor and a 200Ω ±5% resistor in
series between CD1 and PMP.
9 CD2
NEG Charge-Pump Capacitor Connection 2. Connect a 1µF capacitor and a 200Ω ±5% resistor in
series between CD2 and PMPB.
10 NEG
Output of Inverting (-2x) Charge Pump. Bypass NEG to GND with a 1µF capacitor. Output is internally
discharged with a 1.5kΩ resistor when V
ONBIAS
= 0V.
Pin Description
Typical Operating Characteristics (continued)
(Circuit of Figure 3, V
IN
= 3.6V, I
LED
= 20mA, 4 LEDs, CTRL = IN, T
A
= +25°C, unless otherwise noted.)
P1-P3P4-P6P7-P9P10-P12P13-P13

MAX1579ETG+

Mfr. #:
Buy MAX1579ETG+
Manufacturer:
Maxim Integrated
Description:
LED Lighting Drivers Cmplete Bias & White LED Power Supply
Lifecycle:
New from this manufacturer.
Delivery:
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