MAX868EUB+T Maxim Integrated Products, MAX868EUB+T Datasheet - Page 7

• Manufacturer Part Number: MAX868EUB+T
• Description: IC CHARGE PUMP INV 10-UMAX
• Manufacturer: Maxim Integrated Products
• Type: Switched Capacitor (Charge Pump), Doubler, Invertingr

Specifications of MAX868EUB+T

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -3.6 ~ -11 V
• Current - Output: 30mA
• Frequency - Switching: 450kHz
• Voltage - Input: 1.8 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Power - Output: 444mW
• Function: Inverting
• Output Voltage: - 3.6 V to - 11 V
• Output Current: 30 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 4. Setting the Output Voltage Using Two External
Resistors
Proper choice of the flying capacitors is dependent pri-
marily upon the desired output current. For flying capaci-
tors in the 0.1µF to 0.33µF range, the maximum output
current can be approximated by the following equation:
where f
450kHz), R
impedance (typically 70 ), and C1 and C2 are the flying-
capacitor values. As a general rule, choose the lowest-
value flying capacitors that provide the desired output
current in order to minimize output voltage ripple (see the
section Choosing the Output Capacitor ).
Table 1. Manufacturers of Surface-Mount, Low-ESR Capacitors
Surface-Mount Tantalum
Surface-Mount Ceramic
I
OUT(MAX)
CONNECTION
MAX
OPTIONAL
TYPE
is the maximum oscillator frequency (typically
V
OUT
REF
V
IN
f
MAX
x C1
is the MAX868 open-loop output
_______________________________________________________________________________________
IN
4
Choosing the Flying Capacitors
R2
MAX868
2 x V
C2
MANUFACTURER
FB
IN
+ R
Capacitor Selection
Sprague
Matsuo
Matsuo
OUT
R1
OUT
AVX
AVX
C
|
C
V
*
OUT
x
*OPTIONAL
V
|
FEED-FORWARD
CAPACITOR
IN
10V
V
OUT
|
V
OUT
|
593D, 595D series
TPS series
267 series
Regulated, Adjustable -2x
X7R type
X7R type
PART
Inverting Charge Pump
Surface-mount ceramic capacitors are preferred, due
to their small size, low cost, and low equivalent series
resistance (ESR). To ensure proper operation over the
entire temperature range, choose ceramic capacitors
with X7R (or equivalent) low temperature-coefficient
(tempco) dielectrics. See Table 1 for a list of suggested
capacitor suppliers.
The output capacitor stores the charge transferred from
the flying capacitors and services the load between
oscillator cycles. A good general rule is to make the
output capacitance at least ten times greater than that
of the flying capacitors.
The output voltage ripple is dependent upon the
capacitance of the flying capacitor and upon the output
capacitor’s capacitance and ESR. When operating in
closed-loop mode (when the MAX868 is generating a
regulated output voltage), use the following equation to
approximate peak-to-peak output voltage ripple:
where C1 and C2 are the flying capacitors, R
output capacitor’s ESR, and R
open-loop output impedance, typically 70 .
Choose a low-ESR output capacitor for minimum output
ripple. Surface-mount ceramic capacitors are preferred
for their small size, low cost, and low ESR; low-ESR tan-
talum electrolytic capacitors are also acceptable. When
using a ceramic output capacitor, ensure proper opera-
tion over the entire temperature range by choosing a
capacitor with X7R (or equivalent) low tempco dielec-
tric. See Table 1 for a list of suggested capacitor sup-
pliers.
V
RIPPLE
2 x V
[phone]
[phone]
[phone]
[phone]
[phone]
IN
PHONE
|
V
OUT
Choosing the Output Capacitor
|
x
1
OUT
4 x C
C1
[phone]
[phone]
[phone]
[phone]
[phone]
1
is the MAX868’s
OUT
FAX
C2
ESR
R
R
OUT
ESR
is the
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