MAX829EUK+T Maxim Integrated Products, MAX829EUK+T Datasheet - Page 6

• Manufacturer Part Number: MAX829EUK+T
• Description: IC INVERTER VOLT SOT23-5
• Manufacturer: Maxim Integrated Products
• Type: Switched Capacitor (Charge Pump), Doubler, Invertingr

Specifications of MAX829EUK+T

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -1.15 ~ 6 V, ±2.3 ~ ±12 V
• Current - Output: 25mA
• Frequency - Switching: 35kHz
• Voltage - Input: 1.5 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Function: Inverting
• Output Voltage: - 1.5 V to - 5.5 V
• Output Current: 25 mA
• Supply Current: 150 uA
• Maximum Operating Temperature: + 85 C
• Input Voltage: 1.5 V to 5.5 V
• Maximum Power Dissipation: 571 mW
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Switching Frequency: 35 KHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Switched-Capacitor Voltage Inverters
Increasing the flying capacitor’s size reduces the output
resistance. Small C1 values increase the output resis-
tance. Above a certain point, increasing C1’s capaci-
tance has a negligible effect, because the output
resistance becomes dominated by the internal switch
resistance and capacitor ESR.
Increasing the output capacitor’s size reduces the output
ripple voltage. Decreasing its ESR reduces both output
resistance and ripple. Smaller capacitance values can
be used with light loads if higher output ripple can be
tolerated. Use the following equation to calculate the
peak-to-peak ripple:
Bypass the incoming supply to reduce its AC impedance
and the impact of the MAX828/MAX829’s switching noise.
The recommended bypassing depends on the circuit
configuration and on where the load is connected.
When the inverter is loaded from OUT to GND, current
from the supply switches between 2 x I
Therefore, use a large bypass capacitor (e.g., equal to
the value of C1) if the supply has a high AC impedance.
When the inverter is loaded from IN to OUT, the circuit
draws 2 x I
spikes. A 0.1µF bypass capacitor is sufficient.
The most common application for these devices is a
charge-pump voltage inverter (Figure 1). This application
requires only two external components—capacitors C1
and C2—plus a bypass capacitor, if necessary. Refer to
Table 1. Low-ESR Capacitor Manufacturers
6
AVX
Matsuo
Sanyo
Sprague
_______________________________________________________________________________________
V
RIPPLE
MANUFACTURER
OUT
=
constantly, except for short switching
f
OSC
I
USA
Japan
OUT
x C2
+ 2
Input Bypass Capacitor
Output Capacitor (C2)
Flying Capacitor (C1)
Voltage Inverter
x I
OUT
OUT
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81-7-2070-6306
[phone]
x ESR
and zero.
PHONE
C
2
the Capacitor Selection section for suggested capacitor
types and values.
Two devices can be cascaded to produce an even
larger negative voltage (Figure 4). The unloaded output
voltage is normally -2 x V
by the output resistance of the first device multiplied by
the quiescent current of the second. When cascading
more than two devices, the output resistance rises dra-
matically. For applications requiring larger negative
voltages, see the MAX864 and MAX865 data sheets.
Paralleling multiple MAX828s or MAX829s 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. The
equation for calculating output resistance is also shown
in Figure 5.
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 40mA.
[phone]
[phone]
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81-7-2070-1174
[phone]
FAX
Combined Doubler/Inverter
Surface-mount, TPS series
Surface-mount, 267 series
Through-hole, OS-CON series
Surface-mount, 595D series
IN
, but this is reduced slightly
Paralleling Devices
Cascading Devices
DEVICE TYPE