MAX1658ESA Maxim Integrated Products, MAX1658ESA Datasheet - Page 7

• Manufacturer Part Number: MAX1658ESA
• Description: IC REG LINEAR 350MA LDO 8-SOIC
• Manufacturer: Maxim Integrated Products

Specifications of MAX1658ESA

• Regulator Topology: Positive Fixed or Adjustable
• Voltage - Output: 3.3V, 1.25 ~ 16 V
• Voltage - Input: 2.7 ~ 16.5 V
• Voltage - Dropout (typical): 0.65V @ 350mA
• Number Of Regulators: 1
• Current - Output: 350mA (Min)
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Number Of Outputs: 1
• Polarity: Positive
• Input Voltage Max: 16.5 V
• Output Voltage: 1.25 V to 16 V, 3.3 V
• Output Type: Adjustable, Fixed
• Dropout Voltage (max): 1.5 V at 350 mA
• Output Current: 350 mA
• Line Regulation: 0.05 % / V
• Load Regulation: 0.003 % / mA
• Voltage Regulation Accuracy: 3 %
• Maximum Power Dissipation: 1.2 W
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Reference Voltage: 1.246 V
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Limit (min): -

The MAX1658/MAX1659 feature an internal P-channel
MOSFET pass transistor. Using a MOSFET provides
several advantages over similar PNP designs, including
lower dropout voltage and extended battery life. Unlike
bipolar transistors, MOSFETs reduce quiescent current,
because they require no base current, particularly at
heavy loads and in dropout. As a result, the
MAX1658/MAX1659 operate at a low quiescent current
even in dropout.
Dual Mode operation allows the MAX1658/MAX1659 to
operate at either a preset or a user-adjustable output
voltage. The device compares the SET pin voltage with
an internal 65mV reference. If the voltage is lower than
65mV (typically achieved by grounding SET), the
device switches to an internal resistor-divider feedback
network that sets the output voltage. The MAX1658’s
preset output voltage is 3.3V and the MAX1659’s is 5V
(Figure 2).
If the SET pin is not below 65mV, the device switches to
external feedback and SET becomes a feedback input.
The feedback network can be configured to produce
an output between 16V and the voltage reference
(nominally 1.21V). Under regulation, the feedback
mechanism adjusts the error signal such that the volt-
age at the SET pin equals the reference voltage.
Therefore, to achieve the minimum output, connect SET
directly to OUT. For other voltages, a resistive voltage-
divider network is necessary. Figure 3 shows the topol-
Figure 2. Preset Output Configuration
VOLTAGE
INPUT
ON
0.1 F
OFF
3, 6, 7
2
_______________________________________________________________________________________
SHDN
IN
P-Channel Pass Transistor
GND
Output Voltage Selection
8
(MAX1659)
MAX1658
SET
1
OUT
4, 5
Low-Dropout Linear Regulators
OUTPUT VOLTAGE
3.3V/350mA
(5V/350mA)
10 F
ogy of a typical circuit operating in adjustable mode.
The output voltage is set by the following equation:
where V
The input leakage current of the SET input is less than
25nA. This allows the use of large resistors in the feed-
back network to minimize output current loss without
compromising accuracy. R2 can be as high as 500kΩ
in most applications.
A logic low on the SHDN pin places the MAX1658/
MAX1659 in shutdown. This mode deactivates all func-
tions, including the pass transistor. The device con-
sumes less than 1µA of supply current in shutdown,
and its output becomes high impedance. The
MAX1658/MAX1659 exit shutdown in 100µs.
The MAX1658/MAX1659 include current-limiting circuit-
ry that monitors and controls the pass transistor and
limits output current to around 900mA. The output can
be shorted to ground indefinitely without damaging the
device.
Figure 3. Adjustable Output Configuration Using External
Feedback Resistors
VOLTAGE
0.1 F
INPUT
350mA, 16.5V Input,
SET
3, 6, 7
= 1.21V. Solving for R1 yields:
2
V
OUT
R1 = R2
V
V
IN
SHDN
OUT
SET
= 1.21V
= V
MAX1658
MAX1659
SET
GND
(
V
1 + R1
SET
8
R2
V
V
Output Current Limit
OUT
SET
)
OUT
SET
1
4, 5
1
R
R
1
2
1
R2
R1
Shutdown
C
10 F
OUT
OUTPUT
VOLTAGE
7