3.3V-Input to Regulated 5V-Output
Charge Pumps
Typical Operating Characteristics (continued)
(Circuit of Figure 5, V
IN
= 3.3V, component values from Tables 2 and 3, T
A
= +25°C, unless otherwise noted.)
MAX682/MAX683/MAX684
SHUTDOWN TIMING
MAX682 TOC18
LINE-TRANSIENT RESPONSE
MAX682 TOC20
LOAD-TRANSIENT RESPONSE
MAX682 TOC19
A
A
A
B
B
B
100µs/div
A: OUTPUT VOLTAGE: SKIP = HIGH, R
L
= 5V / I
MAX
, 2V/div
B: SHDN VOLTAGE: 1V/div
2ms/div
A: INPUT VOLTAGE: V
IN
= 3.1V TO 3.6V, 500mV/div
B: OUTPUT VOLTAGE: SKIP = HIGH, I
SHDN
= 22µA,
I
LOAD
= 250mA, 50mV/div, MAX682
2ms/div
A: LOAD CURRENT: I
LOAD
= 5mA TO 250mA, 500mA/div
B: OUTPUT VOLTAGE: SKIP = HIGH, I
SHDN
= 22µA,
100mV/div, MAX682
Pin Description
PIN
1
NAME
SKIP
FUNCTION
When
SKIP
= low, the regulator operates in low-quiescent-current skip mode. When
SKIP
= high, the
regulator operates in constant-frequency mode, minimizing output ripple and noise.
SKIP
must be tied
high for input voltages above 3.6V.
Shutdown Input. Drive
SHDN
through an external resistor. When
SHDN
= low, the device turns off. When
current is sourced into
SHDN
through R
EXT
, the device activates, and the
SHDN
pin input current sets the
oscillator’s switching frequency. R
EXT
(kΩ) = 45000 (V
IN
- 0.69V) / f
OSC
(kHz).
Input Supply Pin. Can range from 2.7V to 5.5V for
SKIP
= high, and 2.7V to 3.6V for
SKIP
= low. Bypass to
PGND with a suitable value capacitor (see
Capacitor Selection
section).
Ground Pin. Connect to PGND through a short trace.
Power Ground Pin
Negative Terminal of the Charge-Pump Transfer Capacitor
Positive Terminal of the Charge-Pump Transfer Capacitor
Fixed 5V Power Output. Bypass to PGND with output filter capacitor.
2
SHDN
3
4
5
6
7
8
IN
GND
PGND
CXN
CXP
OUT
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5
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