MIC23150-SYMT EV Micrel, MIC23150-SYMT EV Datasheet - Page 2

• Manufacturer Part Number: MIC23150-SYMT EV
• Description: Power Management IC Development Tools 2.0A 4MHz HyperLight Load Buck Regulator - Evaluation Board
• Manufacturer: Micrel
• Type: DC/DC Converters, Regulators & Controllersr

Specifications of MIC23150-SYMT EV

• Product: Evaluation Boards
• Tool Is For Evaluation Of: MIC23150
• Input Voltage: 2.7 V to 5.5 V
• Output Voltage: 3.3 V
• Description/function: Evaluation Board
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Output Current: 120 mA
• For Use With: MIC23150

HyperLight Load™ Mode
MIC23150 uses a minimum on and off time proprietary
control loop (patented by Micrel). When the output voltage
falls below the regulation threshold, the error comparator
begins a switching cycle that turns the PMOS on and
keeps it on for the duration of the minimum-on-time. This
increases the output voltage. If the output voltage is over
the regulation threshold, then the error comparator turns
the PMOS off for a minimum-off-time until the output drops
below the threshold. The NMOS acts as an ideal rectifier
that conducts when the PMOS is off. Using a NMOS
switch instead of a diode allows for lower voltage drop
across the switching device when it is on. The
asynchronous switching combination between the PMOS
and the NMOS allows the control loop to work in
discontinuous mode for light load operations. In
discontinuous mode, the MIC23150 works in pulse
frequency modulation (PFM) to regulate the output. As the
output current increases, the off-time decreases, thus
provides more energy to the output. This switching
scheme improves the efficiency of MIC23150 during light
load currents by only switching when it is needed. As the
load current increases, the MIC23150 goes into
continuous conduction mode (CCM) and switches at a
frequency centered at 4MHz. The equation to calculate the
load when the MIC23150 goes into continuous conduction
mode may be approximated by the following formula:
Micrel, Inc.
August 2009
I
LOAD
>
Ê
Á Á
Ë
(
V
IN
-
2
V
L
OUT
¥
f
)
¥
D
ˆ
˜ ˜
¯
2
As shown in the previous equation, the load at which
MIC23150 transitions from HyperLight Load™ mode to
PWM mode is a function of the input voltage (V
voltage (V
frequency (f). As shown in Figure 1, as the Output Current
increases, the switching frequency also increases until the
MIC23150 goes from HyperLight Load
mode at approximately 120mA. The MIC23150 will switch
at a relatively constant frequency around 4MHz once the
output current is over 120mA.
Figure 1. SW Frequency vs. Output Current
OUT
), duty cycle (D), inductance (L) and
0.001
0.01
0.1
10
1
1
V
IN
OUTPUT CURRENT (mA)
= 3.0V
vs Output Current
10
SW Frequency
V
100
MIC23150 Evaluation Board
IN
= 4.2V
L = 4.7µH
V
C
V
OUT
OUT
IN
= 3.6V
1000
= 1.8V
= 4.7µF
TM
10000
M9999-081709-A
mode to PWM
IN
), output