MAX1606 Datasheet, PDF (6/10 Pages) Maxim Integrated Products – 28V Internal Switch LCD Bias Supply with True Shutdown

28V Internal Switch LCD Bias Supply
with True Shutdown
Typical Operating Characteristics (continued)
(V_CC = 3.3V, V_BATT = 3.6V, L1 = 10µH, SHDN = LIM = V_CC, V_OUT(NOM) = 18V (Figure 3), T_A = +25°C, unless otherwise noted.)
6V
4V
2V
18.1V
18V
17.9V
LINE TRANSIENT
MAX1606 toc13
A
B
10mA
0
18.1V
18V
17.9V
500mA
0
LOAD TRANSIENT
MAX1606 toc14
A
B
C
4V
2V
0
20V
10V
0
500mA
0
SHUTDOWN WAVEFORM
MAX1606 toc15
A
B
C
100µs/div
A: V_BATT = V_CC = 2.4V TO 5.5V, 2V/div
B: V_OUT = 18V, R_OUT = 3.6kΩ, 100mV/div
40µs/div
A: I_OUT = 1mA TO 10mA, 10mA/div
B: V_OUT = 18V, 100mV/div
C: I_L1, 500mA/div
400µs/div
A: V_SHDN, 2V/div
B: V_OUT, 10V/div, R_OUT = 1.8kΩ
C: I_L1, 500mA/div
Pin Description
PIN
NAME
FUNCTION
Inductor Supply Voltage, 0.8V to 5.5V. Internally connected to the source of a P-channel
1
BATT
MOSFET used to isolate the output from the input during shutdown. Bypass with a 10µF or
greater capacitor.
2
FB
Feedback Input. Connect to a resistive divider network between the output and GND to set the
output voltage between V_BATT and 28V. The feedback threshold is 1.25V.
3
V_CC
IC Supply Voltage, 2.4V to 5.5V. Bypass V_CC to GND with a 1µF or greater capacitor.
4
GND
Ground
5
LX
Inductor Switching Connection. Internally connected to the drain of a 28V N-channel MOSFET.
LX is high impedance in shutdown.
6
LIM
Inductor Current-Limit Selection. Connect LIM to V_CC for 500mA, leave LIM floating for 250mA,
or connect LIM to GND for 125mA.
Active-Low Shutdown Input. A logic low shuts down the device and reduces the supply current
7
SHDN
to 0.1µA. When shutdown, the MAX1606 isolates the output from the input by turning off the P-
channel MOSFET between BATT and SW. Connect SHDN to V_CC for normal operation.
8
SW
Isolation Switch Output, Inductor Connection. Internally connected to the drain of a P-channel
MOSFET used to isolate the output from the input during shutdown.
6 _______________________________________________________________________________________