MAX1606 Maxim, MAX1606 Datasheet - Page 7

• Manufacturer Part Number: MAX1606
• Description: 28V Internal Switch LCD Bias Supply with True Shutdown
• Manufacturer: Maxim

The MAX1606 step-up DC-DC converter operates from a
2.4V to 5.5V supply and converts voltages as low as
0.8V up to 28V. The device includes an internal switch-
ing MOSFET with a 0.8Ω on-resistance and selectable
current limit (Figure 1) and consumes 160µA of supply
current. During startup, the MAX1606 extends the mini-
mum off-time, limiting initial battery surge current. The
MAX1606 uses a P-channel MOSFET to isolate the out-
put from the input during true shutdown mode. This isola-
tion switch also includes short-circuit current limiting,
Figure 1. Functional Diagram
Figure 2. Setting the Peak Inductor Current Limit
V
V
IN
CC
= 0.8V TO 5.5V
= 2.4V TO 5.5V
(2.4V TO 5.5V)
ON
V
C1
C2
CC
_______________________________________________________________________________________
OFF
V
GND
LIM
CC
I PEAK = 500mA
Detailed Description
MAX1606
28V Internal Switch LCD Bias Supply
BATT
V
LIM
SHDN
CC
SHUTDOWN
LOGIC
NO CONNECTION
(2.4V TO 5.5V)
V
CC
CONTROL
LOGIC
ERROR
AMPLIFIER
V
LIM
GND
CC
I PEAK = 250mA
MAX1606
MAX1606
which protects the inductor and diode during a short-cir-
cuit fault.
The MAX1606 features a minimum off-time, current-limit-
ed control scheme. The duty cycle is governed by a pair
of one-shots that set a minimum off-time and a maximum
on-time. The switching frequency can be up to 500kHz
and depends upon the load and input voltage. The peak
current limit of the internal N-channel MOSFET is pin
selectable and may be set at 125mA, 250mA, or 500mA
(Figure 2).
CURRENT
LIMIT
1.25V
I
LIM
with True Shutdown
(2.4V TO 5.5V)
N
SW
LX
FB
V
CC
C
FF
L1
10µH
LIM
GND
V
CC
I PEAK = 125mA
D1
MAX1606
Control Scheme
R1
R2
V
OUT
= V
IN
TO 28V
C
OUT
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