MAX1759EUB-T Maxim Integrated Products, MAX1759EUB-T Datasheet - Page 8

• Manufacturer Part Number: MAX1759EUB-T
• Description: Charge Pumps Buck/Boost Regulating
• Manufacturer: Maxim Integrated Products

Specifications of MAX1759EUB-T

• Function: Step Up, Step Down
• Output Voltage: 3.3 V, 2.5 V to 5.5 V
• Output Current: 100 mA
• Maximum Operating Temperature: + 85 C
• Package / Case: uMAX-10
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT

Buck/Boost Regulating
Charge Pump in µMAX
Optimize the charge-pump circuit for physical size, out-
put current, and output ripple by selecting capacitors
C
values.
Note that capacitors must have low ESR (≤20mΩ) to
maintain low output ripple. Ceramic capacitors are
recommended. In cost-sensitive applications where high
output current is needed, the output capacitor may be a
combination of a 1µF ceramic in parallel with a 10µF tan-
talum capacitor. The ceramic capacitor’s low ESR will
help keep output ripple within acceptable levels.
The MAX1759 proprietary control scheme automatically
chooses between voltage doubling and voltage step-
down to maintain output voltage regulation over various
load currents and V
When V
operates in voltage-doubler mode. It regulates the output
voltage by modulating the charge delivered by the
transfer capacitor.
When V
ates in voltage step-down mode, but may revert to volt-
age-doubler mode if necessary to maintain regulation
under load. While operating in step-down mode, the
output voltage ripple is typically much lower than it is in
voltage-doubler mode (see Typical Operating
Characteristics).
The MAX1759 is guaranteed to deliver a regulated 3.3V
at 100mA continuous, from a +2.5V input. Peaks up to
200mA are acceptable as long as the current is
≤100mA (RMS).
The MAX1759 is a high-frequency switched-capacitor
voltage regulator. For best circuit performance, use a
ground plane and keep C
resistors (if used) close to the device. If using external
feedback, keep the feedback node as small as possi-
ble by positioning the feedback resistors very close to
FB. Suggested PC component placement and board
layout are shown in Figures 4a and 4b.
TRANSISTOR COUNT: 1802
8
IN
, C
_______________________________________________________________________________________
X
, and C
IN
IN
is lower than V
is higher than V
OUT
Applications Information
. See Table 1 for suggested capacitor
IN
to V
OUT
OUT
OUT
IN
Output Voltage Ripple
, C
Chip Information
, the charge pump always
Capacitor Selection
, the charge pump oper-
voltage differentials.
X
, C
PC Board Layout
OUT
Output Current
, and feedback
Table 1. Capacitor Selection
Figure 3. Using External Feedback for Regulated 2.5V Output
CURRENT
OUTPUT
V
(mA)
IN
100
100
50
= 1.6V TO 5.5V
10µF
(µF)
C
4.7
2.2
10
CAPACITOR VALUE
IN
IN
SHDN
CXN
GND
MAX1759
0.33µF
0.33
0.22
(µF)
0.1
C
X
PGND
CXP
OUT
POK
FB
C
(µF)
4.7
2.2
OUT
10
10µF
OUTPUT RIPPLE
V
2.5V
100
R1
76.8k
R2
75k
IN
40
80
=
100k
(mV)
V
OUT
= 2.5V
V
4.2V
20
60
80
IN
=