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零件编号 | PM8903 | ||
描述 | 3A step-down monolithic switching regulator | ||
制造商 | STMicroelectronics | ||
LOGO | |||
1 Page
PM8903
3 A step-down monolithic switching regulator
Features
■ Integrated 35 mΩ MOSFETs for high efficiency
■ 3 A continuous output current
■ 2.8 V to 6 V input voltage (VIN)
■ 2.9 V to 5.5 V supply voltage (VCC)
■ Adjustable output voltage down to 0.6 V
■ 1% output voltage accuracy
■ 1.1 MHz switching frequency operation
■ PSKIP mode to optimize light load efficiency
■ Embedded bootstrap diode
■ Thermally compensated loss-less current
sense across HS and LS MOSFETs
■ OV/UV/OC and overtemperature protection
■ Internal soft-start and soft-stop
■ Interleaving synchronization (Up to 2 ICs)
■ Power Good output
■ Shutdown function (<15 μA quiescent current)
■ VFQFPN16 3 x 3 mm compact package
Applications
■ Subsystem power supply
■ CPU, DSP and FPGA power supply
■ Distributed power supply
■ General DC-DC converters
VFQFPN16 3x3 mm
Description
The PM8903 is a high efficiency monolithic step-
down switching regulator designed to deliver up to
3 A continuous current. The IC operates from 2.8
V to 6 V input voltage (VIN).
The PM8903 features low-resistance integrated
nMOS and proprietary pulse-skipping mode for
optimum efficiency over all the loading range.
The voltage mode control loop allows the widest
range of output filter. Current sense is internally
thermally compensated for optimum precision.
The integrated 0.6 V reference allows the
regulation of output voltages with ±1% accuracy
over temperature variations. Switching frequency
is typically set to 1.1 MHz and can be
programmed to 0.8 MHz or 1.0 MHz. Out of phase
synchronization allows the reduction of input RMS
current.
The PM8903 provides precise dual-threshold
overcurrent protection as well as over /
undervoltage and overtemperature protection.
PGOOD output easily provides real-time
information on the output voltage.
Table 1. Device summary
The PM8903 is available in VFQFPN16 3 x 3 mm.
Order codes
Package
Packing
PM8903
PM8903TR
VFQFPN16 3x3 mm
VFQFPN16 3x3 mm
Tube
Tape and reel
February 2012
Doc ID 022748 Rev 1
1/34
www.st.com
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http://www.Datasheet4U.com
Electrical specifications
4 Electrical specifications
4.1
Absolute maximum ratings
Table 4. Absolute maximum ratings
Symbol
Parameter
VCC
VIN
VBOOT
VPHASE
VPGOOD
VSYNCH, VEN
to PGND, GND
to PGND, GND
to PGND, GND
to PHASE
to PGND, GND
to PGND, GND, VIN=6 V, t<100 nsec.
to PGND, GND
to PGND, GND
All other pins to GND
4.2 Recommended operating conditions
Table 5. Recommended operating conditions
Symbol
Parameter
VIN Power supply voltage
VCC Signal supply voltage
PM8903
Value
-0.3 to 6
-0.3 to 7
-0.3 to 13
-0.3 to 6
-0.3 to 7
-1.7 to 7.5
-0.3 to 7
-0.3 to 6
-0.3 to 3.6
Unit
V
V
V
V
V
V
V
Min.
2.8
2.9
Typ.
-
-
Max.
6
5.5
Unit
V
V
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Device description
PM8903
5.3.2
5.3.3
The protection is triggered when the voltage sensed on the FB pin rises over the OVP
threshold (0.72 V typ.) and the device acts as follows:
● HS MOSFET is suddenly forced OFF
● LS MOSFET is turned on (to discharge the output and protect the load) until VFB drops
to 0.3 V, then it is turned off (to avoid negative spikes on output voltage). If VFB
recrosses OVP rising threshold, LS is turned on again
This protection state is latched, cycle EN or VCC to recover.
Undervoltage protection
Undervoltage protection is active from the end of soft-start.
If VFB falls below the UVP threshold (0.48 V typ.), undervoltage protection is triggered and
the device starts a soft-off sequence (see Section 5.2.2).
This protection state is latched, cycle EN, VCC or VIN to recover.
Feedback disconnection protection
In order to protect the load even if the FB pin is not connected to the PCB, a 100 nA current
is constantly sourced from the FB pin: if the FB pin is left floating, it is internally pulled high
triggering OVP protection and preventing VOUT from rising out of control.
Figure 10. FB disconnection
VOUT
RFB
FB
720mV
ROS
OVP
COMPARATOR
5.3.4
Power Good (PGOOD)
PGOOD is an open drain output, left floating when VOUT is in regulation at the programmed
voltage, at the end of soft-start.
PGOOD is forced low, to communicate that the output voltage is no longer in regulation, if
one of the following conditions is verified:
● The voltage of the FB pin exits from the PGOOD window (±20% of VREF)
● The device is disabled, EN is forced low
● VCC voltage is below the UVLO threshold
● Any protection is triggered (OVP, UVP, OCP, OTP)
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页数 | 30 页 | ||
下载 | [ PM8903.PDF 数据手册 ] |
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