5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller
MAX608
______________________________________________________________Pin Description
PIN
1
2
3
NAME
EXT
OUT
FB
FUNCTION
Gate Drive for External N-Channel Power Transistor
Power-Supply and Voltage-Sense Input. Always connect OUT to circuit output.
Feedback Input for Adjustable-Output Operation. Connect to ground for fixed-output operation.
Use a resistor divider network to adjust the output voltage. See
Setting the Output Voltage
section.
Active-High TTL/CMOS Logic-Level Shutdown Input. In shutdown mode, V
OUT
is a diode drop
below the input voltage (due to the DC path from the input voltage to the output). Connect to
ground for normal operation.
1.5V Reference Output that can source 100µA for external loads. Bypass to GND with 0.1µF.
The reference is disabled in shutdown.
Analog Ground
High-Current Ground Return for the Output Driver
Positive Input to the Current-Sense Amplifier. Connect the current-sense resistor between CS
and AGND.
4
SHDN
5
6
7
8
REF
AGND
GND
CS
REF
FB
DUAL-MODE
COMPARATOR
SHDN
BIAS
CIRCUITRY
MAX608
50mV
1.5V
REFERENCE
MIN OFF-TIME
ONE-SHOT
Q
TRIG
2.3µs
F/F
S
R
MAX ON-TIME
ONE-SHOT
TRIG
Q
16µs
LOW-VOLTAGE
OSCILLATOR
2.5V
Q
N
ERROR
COMPARATOR
LOW-VOLTAGE
START-UP
COMPARATOR
OUT
EXT
CURRENT-SENSE
AMPLIFIER
0.1V
CS
Figure 1. Functional Diagram
6
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
