MCP1253-ADJI/MS Microchip Technology, MCP1253-ADJI/MS Datasheet - Page 10

• Manufacturer Part Number: MCP1253-ADJI/MS
• Description: IC CHRG PUMP DC/DCCONV ADJ 8MSOP
• Manufacturer: Microchip Technology
• Type: Step-Down (Buck), Step-Up (Boost), Switched Capacitor (Charge Pump)r

Specifications of MCP1253-ADJI/MS

• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.5 ~ 5.5 V
• Current - Output: 120mA
• Frequency - Switching: 1MHz
• Voltage - Input: 2 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Function: Step Up/Step Down
• Output Voltage: 1.5 V to 5.5 V
• Output Current: 120 mA
• Maximum Operating Temperature: + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

MCP1252/3
4.2
The power efficiency, , is determined by the mode of
operation. In boost mode, the efficiency is approxi-
mately half of a linear regulator. In buck mode, the effi-
ciency is approximately equal to that of a linear
regulator. The following formulas can be used to
approximate the power efficiency with any significant
amount of output current. At light loads, the quiescent
current of the device must be taken into consideration.
EQUATION
4.3
Driving SHDN low places the MCP1252 or MCP1253 in
a low power shutdown mode. This disables the charge
pump switches, oscillator and control logic, reducing
the quiescent current to 0.1 µA (typical). The PGOOD
output is in a high-impedance state during shutdown.
4.4
The PGOOD output is an open-drain output that sinks
current when the regulator output voltage falls below
0.93V
fixed when the selectable output device is chosen
(MCP1252-33X50, MCP1253-33X50) or adjustable
from an external resistive divider when the adjustable
device is chosen (MCP1252-ADJ, MCP1253-ADJ). If
the regulator output voltage falls below 0.93V
ical) for less than 200 µsec and then recovers, glitch-
immunity circuits prevent the PGOOD signal from tran-
sitioning low. A 10 k
PGOOD to V
Connect PGOOD to GND or leave unconnected if not
used.
4.5
The MCP1252 and MCP1253 features foldback short-
circuit protection. This circuitry provides an internal
soft-start function by limiting in-rush current during
startup and also limits the output current to 200 mA
(typical) if the output is shorted to GND. The internal
soft-start circuitry requires approximately 300 µsec,
typical with a 5V output, from either initial power-up or
release from shutdown for the output voltage to be in
regulation.
DS21752A-page 10
BOOST
OUT
BUCK
Power Efficiency
Shutdown Mode
PGOOD Output
Soft-Start and Short-Circuit
Protection
(typical). The output voltage can either be
=
OUT
P
-------------
=
P
OUT
IN
P
-------------
may be used to provide a logic output.
P
OUT
IN
=
------------------------------------
V
=
to 1 M
V
IN
O UT
V
------------------------------- -
V
OU T
IN
2
I
OU T
I
I
O UT
OU T
I
pull-up resistor from
OUT
=
=
----------------- -
V
V
V
-------------
IN
V
OUT
OU T
IN
OUT
2
(typ-
4.6
The MCP1252 and MCP1253 feature thermal shut-
down with temperature hysteresis. When the die tem-
perature exceeds 160°C, typically, the device shuts
down. When the die cools by 15°C, typically, the device
automatically turns back on. If high die temperature is
caused by output overload and the load is not removed,
the device will turn on and off, resulting in a pulse out-
put.
5.0
The MCP1252 and MCP1253 are inductorless, positive
regulated, charge pump DC/DC converters. A typical
circuit configuration for the fixed output version is
depicted in Figure 5-1. The adjustable version is
depicted in Figure 5-2.
FIGURE 5-1:
for Fixed Output Device.
FIGURE 5-2:
for Adjustable Output Device.
Shutdown
Shutdown
C
2.7V to 5.5V
2.7V to 5.5V
OFF
Control
C
OFF
Control
IN
IN
C
+
C
+
+
ON
ON
FLY
FLY
SELECTABLE OUTPUT VOLTAGE
ADJUSTABLE OUTPUT VOLTAGE
Thermal Shutdown
APPLICATIONS
V
7
6
5
3
3
7
6
5
OUT
MCP1252-33X50
C+
C-
V
SHDN
C+
C-
V
SHDN
MCP1252-ADJ
IN
IN
= 1.21V (1 + R
Typical Circuit Configuration
Typical Circuit Configuration
GND
GND
4
4
SELECT
2002 Microchip Technology Inc.
PGOOD
PGOOD
V
V
OUT
OUT
FB
1
/R
2
1
8
2
1
8
2
)
+5.0V ±2.5%
R
R
PGOOD Flag
To PICmicro
Microcontroller
R
R
PGOOD Flag
To PICmicro
Microcontroller
C
C
C
R
+4.0V
PU
1
2
PU
C
C
C
R
R
R
FLY
IN
OUT
PU
FLY
IN
OUT
PU
1
2
= 23.2 k
= 10 k
= 10 µF
= 100 k
= 10 µF
= 1 µF
= 100 k
+
= 10 µF
= 1 µF
= 10 µF
+
C
C
OUT
OUT
®
®