MAX1578-MAX1579 Datasheet, PDF (6/13 Pages) Maxim Integrated Products – Complete Bias and White LED Power Supplies for Small TFT Displays

Complete Bias and White LED Power Supplies
for Small TFT Displays
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.)
MAIN OUTPUT LOAD REGULATION
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
0
5
10
15
20
25
LOAD CURRENT (mA)
POS AND NEG LOAD REGULATION
0
-0.5
-1.0
-1.5
POS
-2.0
-2.5
NEG
-3.0
-3.5
-4.0
-4.5
-5.0
0
20
40
60
80 100
LOAD CURRENT (µA)
Pin Description
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.
6
PMP
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.
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