MAX1720EUT+T Maxim Integrated Products, MAX1720EUT+T Datasheet - Page 8

• Manufacturer Part Number: MAX1720EUT+T
• Description: IC VOLT INV SW CAP SOT23-6
• Manufacturer: Maxim Integrated Products
• Type: Switched Capacitor (Charge Pump), Invertingr

Specifications of MAX1720EUT+T

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -1.5 ~ -5.5 V
• Current - Output: 25mA
• Frequency - Switching: 12kHz
• Voltage - Input: 1.5 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Power - Output: 696mW
• Function: Inverting
• Output Voltage: - 1.25 V to - 5.5 V
• Output Current: 25 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Paralleling multiple MAX1719s, MAX1720s, or
MAX1721s reduces the output resistance. Each device
requires its own pump capacitor (C1), but the reservoir
capacitor (C2) serves all devices (Figure 5). Increase
C2’s value by a factor of n, where n is the number of
parallel devices. Figure 5 shows the equation for calcu-
lating output resistance.
In the circuit of Figure 6, capacitors C1 and C2 form the
inverter, while C3 and C4 form the doubler. C1 and C3
are the pump capacitors; C2 and C4 are the reservoir
capacitors. Because both the inverter and doubler use
part of the charge-pump circuit, loading either output
causes both outputs to decline toward GND. Make sure
the sum of the currents drawn from the two outputs
does not exceed 25mA.
Under heavy loads, where a higher supply is sourcing
current into OUT, the OUT supply must not be pulled
above ground. Applications that sink heavy current into
SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8
© 2004 Maxim Integrated Products
Figure 5. Paralleling MAX1719s or MAX1720s or MAX1721s to
Reduce Output Resistance
_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
C1
SHDN (MAX1719)
SHDN (MAX1720/
R
O
=
R
NUMBER OF DEVICES
O
MAX1721)
OF SINGLE DEVICE
3
4
6
MAX1719
MAX1720
MAX1721
5
“1”
Heavy Load Connected to a
Combined Doubler/Inverter
2
1
C1
+V
IN
Paralleling Devices
…
…
6
3
4
Positive Supply
V
MAX1719
MAX1720
MAX1721
OUT
“n”
Printed USA
= -V
5
IN
2
1
V
C2
OUT
OUT require a Schottky diode (1N5817) between GND
and OUT, with the anode connected to OUT (Figure 7).
Good layout is important, primarily for good noise per-
formance. To ensure good layout, mount all compo-
nents as close together as possible, keep traces short
to minimize parasitic inductance and capacitance, and
use a ground plane.
Figure 6. Combined Doubler and Inverter
TRANSISTOR COUNT: 85
Figure 7. Heavy Load Connected to a Positive Supply
SHDN (MAX1719)
SHDN (MAX1720)
C1
is a registered trademark of Maxim Integrated Products.
(MAX1721)
3
4
6
MAX1719
MAX1720
MAX1721
MAX1719
MAX1720
MAX1721
C3
GND
OUT
5
4
1
2
1
Layout and Grounding
+V
Chip Information
IN
D1
D2
D1, D2 = 1N4148
V+
C2
C4
R
L
V
V
(V
OUT
OUT
FD1
) - (V
= -V
= (2V
IN
FD2
IN
) -
)