MAX1910EUB Maxim Integrated Products, MAX1910EUB Datasheet - Page 4

• Manufacturer Part Number: MAX1910EUB
• Description: LED Drivers 1.5x/2x White LED
• Manufacturer: Maxim Integrated Products

Specifications of MAX1910EUB

• Number Of Segments: 4
• Operating Supply Voltage: 2.7 V to 5.3 V
• Maximum Supply Current: 2.5 mA
• Maximum Power Dissipation: 444 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: uMAX-10
• Minimum Operating Temperature: - 40 C

The MAX1910/MAX1912 are complete charge-pump
boost converters requiring only four small ceramic
capacitors. They employ a 750kHz fixed-frequency
50% duty-cycle clock.
The MAX1910 has two modes of operation: 1.5x and
2x. Each mode has two phases: charge and transfer
(see Figure 1). In 1.5x mode charge phase, transfer
capacitors C1 and C2 charge in series from the input
voltage. In transfer phase, C1 and C2 are configured in
parallel and connected from OUT to IN, transferring
charge to C
unregulated and unloaded, it would generate an output
voltage 1.5 times the input voltage (hence the terms
1.5x/2x High-Efficiency White LED
Charge Pumps
(Circuit of Figure 2, V
4
_______________________________________________________________________________________
PIN
10
1
2
3
4
5
6
7
8
9
OUT
NAME
SHDN
GND
OUT
C1+
C2+
SET
IN1
C2-
IN2
C1-
. If this system were allowed to operate
100
IN
90
80
70
60
50
40
30
20
10
0
= 3.3V, T
2.7
Detailed Description
CIRCUIT OF FIGURE 2
MAX1910 4 WHITE LEDs
I
OUT
Ground
Supply Voltage Input. Connect to IN2. Bypass to GND with a 2.2µF ceramic capacitor.
Transfer Capacitor 2 Connection, Negative Side
Transfer Capacitor 1 Connection, Positive Side
Output. Bypass to GND with a 2.2µF ceramic capacitor.
Shutdown Input. Drive low to turn off the device and disconnect the load from the input. OUT is high
impedance in shutdown. Drive high or connect to IN for normal operation.
Transfer Capacitor 2 Connection, Positive Side
Supply Voltage Input. Connect to IN1.
Transfer Capacitor 1 Connection, Negative Side
SET programs the output current with a resistor from SET to GND. SET can also program the output
voltage with a resistor-divider between OUT and GND.
EFFICIENCY vs. INPUT VOLTAGE
= 60mA
3.0
A
= +25°C, unless otherwise noted.)
INPUT VOLTAGE (V)
3.3
3.6
3.9
Typical Operating Characteristics (continued)
4.2
4.5
“fractional charge pump” and “1.5x mode”). When the
input voltage drops sufficiently, the operating mode
shifts from a 1.5x fractional charge pump to a 2x dou-
bler. C2 is not used in doubler mode. The device transi-
tions out of doubler mode when V
~75% of V
load). The MAX1912 operates only in 1.5x charge-
pump mode.
The output is regulated by controlling the rate at which
the transfer capacitors are charged. The switching fre-
quency and duty cycle are constant, so the output
noise spectrum is predictable. Input and output ripple
are much smaller in value than with other regulating
140
120
100
80
60
40
20
0
FUNCTION
2.7
INPUT CURRENT vs. INPUT VOLTAGE
CIRCUIT OF FIGURE 2
MAX1910
I
LOAD
3.0
= 60mA
OUT
DRIVING 4 LEDS
INPUT VOLTAGE (V)
3.3
for more than 32 clock cycles (at full
3.6
3.9
4.2
Pin Description
Output Regulation
4.5
IN
is greater than