MIC68200_11 Datasheet, PDF (11/16 Pages) Micrel Semiconductor – 2A Sequencing LDO with Tracking and Ramp Control

Micrel, Inc.
Applications Information
Enable Input
The MIC68200 features a TTL/CMOS compatible
positive logic enable input for on/off control of the
device. High (>1V) enables the regulator while low
(<0.2V) disables the regulator. In shutdown the
regulator consumes very little current (only a few
microamperes of leakage). For simple applications the
enable (EN) can be connected to V_IN (IN). While
MIC68200 only requires a few µA’s of enable current
to turn on, actual enable pin current will depend on the
overdrive (voltage exceeding 1V) in each particular
application.
Enable Connections for Logic Driven input
V_IN = 3.3V
Control Logic
High > 1V
MIC68200-1.8BML
IN _U1 OUT
RC Master POR
EN GND DLY
MIC68200-1.5BML
IN _U2 OUT
RC _Slave POR
EN GND DLY
4.7µF
10nF
4.7µF
1nF
Enable Connection for V_IN-Driven and/or Slow
Risetime Inputs
VIN = 3.3V
~ 1V/mSec
10KΩ
10nF
MIC68200-1.8YML
IN _U1 OUT
RC Master POR
EN GND DLY
MIC68200-1.5YML
IN _U2 OUT
RC Slave POR
EN GND DLY
4.7µF
10nF
4.7µF
1nF
MIC68200
Input Capacitor
An input capacitor of 0.1µF or greater is
recommended when the device is more than 4 inches
away from the bulk supply capacitance, or when the
supply is a battery. Small, surface mount chip
capacitors can be used for the bypassing. The
capacitor should be place within 1 inch of the device
for optimal performance. Larger values will help to
improve ripple rejection by bypassing the regulator
input, further improving the integrity of the output
voltage.
Output Capacitor
The MIC68200 requires an output capacitor for stable
operation. As a µCap LDO, the MIC68200 can
operate with ceramic output capacitors of 4.7µF or
greater with ESR’s ranging from a 3mΩ to over
300mΩ. Values of greater than 4.7µF improve
transient response and noise reduction at high
frequency. X7R/X5R dielectric-type ceramic
capacitors are recommended because of their
superior temperature performance. X7R-type
capacitors change capacitance by 15% over their
operating temperature range and are the most stable
type of ceramic capacitors. Larger output
capacitances can be achieved by placing tantalum or
aluminum electrolytics in parallel with the ceramic
capacitor. For example, a 100µF electrolytic in parallel
with a 4.7µF ceramic can provide the transient and
high frequency noise performance of a 100µF ceramic
at a significantly lower cost. Specific
undershoot/overshoot performance will depend on
both the values and ESR/ESL of the capacitors.
February 2011
11
M9999-022311-E