RT9032 Ver la hoja de datos (PDF) - Richtek Technology
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RT9032 Datasheet PDF : 13 Pages
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RT9032
Application Information
Like any low-dropout regulator, the external capacitors used
with the RT9032 must be carefully selected for regulator
stability and performance. Using a capacitor whose value
is > 1μF on the RT9032 input and the amount of
capacitance can be increased without limit. The input
capacitor must be located at a distance of not more than
0.5 inch from the input pin of the IC and returned to a
clean analog ground. Any good quality ceramic or tantalum
can be used for this capacitor. The capacitor with larger
value and lower ESR (equivalent series resistance) provides
better PSRR and line-transient response.
The output capacitor must meet both requirements for
minimum amount of capacitance and ESR in all LDOs
application. The RT9032 is designed specifically to work
with low ESR ceramic output capacitor for space-saving
and performance consideration. Using a ceramic capacitor
whose value is at least 1μF with ESR is > 20mΩ on the
RT9032 output ensures stability. The RT9032 still works
well with output capacitor of other types due to the wide
stable ESR range. Figure 1 shows the curves of allowable
ESR range as a function of load current for various output
capacitor values. Output capacitor of larger capacitance
can reduce noise and improve load transient response,
stability, and PSRR. The output capacitor should be located
at not more than 0.5 inch from the output pin of the RT9032
and returned to a clean analog ground.
100
10
Unstable Range
1
Stable Range
0.1
0.01
0.001
0
Unstable Range
VIN = 5V, CIN = COUT1 = COUT1 = 1μF/X7R
50
100 150 200 250 300
Load Current(mA)
Figure 1
EN
The RT9032 goes into shutdown mode when the EN pin
is in a logic low condition. During this condition, the pass
transistor, error amplifier, and band gap are turned off,
reducing the supply current to be lower than 1uA. The EN
pin can be directly tied to VIN to keep the part on.
Programmable Output Voltage Setting
There are nine sets of the VOUT1 and VOUT2 output
voltages that can be achieved by setting three states (high/
low/open) at the P1 and P2 pins.
The output voltage setting can be achieved by the preset
of P1 and P2 states before VIN power on. However, if the
P1 and P2 states are changed at the condition that only
one of the EN pin is turned off-on, the VOUT1 and VOUT2
voltages will not be changed. The output voltage can be
reset by turning off-on the input power (VIN) or both of EN
pins (EN1 = EN2).
For the output voltage setting please refer to the “Table
for Programmable Output Voltage Setting” in page 2.
Current Limit
The RT9032 contains an independent current limiter, which
monitors and controls the pass transistor’ s gate voltage,
limiting the output current to 430mA (typ.). The output
can be shorted to ground indefinitely without damaging
the part.
Thermal Shutdown Protection
As the die temperature is >170°C, the chip will enter
protection mode. The power MOSFET will be turned-off
during the protection mode to prevent abnormal operation.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature. The power
dissipation definition in device is :
PD = (VIN − VOUT) x IOUT + VIN x IQ
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
10
is a registered trademark of Richtek Technology Corporation.
DS9032-03 August 2012
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