Typical operating characteristics (continued), Pin description – Rainbow Electronics MAX15051 User Manual
Page 7
MAX15050/MAX15051
High-Efficiency, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package
_______________________________________________________________________________________
7
Typical Operating Characteristics (continued)
(V
IN
= 5V, output voltage = 1.8V, I
LOAD
= 4A, and T
A
= +25°C, circuit of Figure 1, unless otherwise noted.)
Pin Description
BUMP
NAME
FUNCTION
A1, A2
GND
Analog/Power Ground. Connect GND to the PCB ground plane at one point near the input bypass
capacitor return terminal as close as possible to the device.
A3, A4
IN
Power-Supply Input. Input supply range is from 2.9V to 5.5V. Bypass IN to GND with a 22µF ceramic
capacitor in parallel to a 0.1µF ceramic capacitor as close as possible to the device.
B1, B2,
B3
LX
Inductor Connection. All LX bumps are internally connected together. Connect all LX bumps to the
switched side of the inductor. LX is high impedance when the device is in shutdown mode.
B4
V
DD
3.3V LDO Output. V
DD
powers the internal analog core. Connect a low-ESR, ceramic capacitor with a
minimum value of 2.2µF from V
DD
to GND.
C1
BST
High-Side MOSFET Driver Supply. Connect BST to LX with a 0.1µF capacitor.
C2, C3
I.C.
Internally Connected. Leave unconnected or connect to ground.
C4
EN
Enable Input. Connect EN to GND to disable the device. Connect EN to IN to enable the device.
D1
PWRGD
Power-Good Output. PWRGD is an open-drain output that goes high impedance when V
FB
exceeds 92.5%
of V
REFIN/SS
and V
REFIN/SS
is above 0.54V. PWRGD is internally pulled low when V
FB
falls below 90% of
V
REFIN/SS
or V
REFIN/SS
is below 0.54V. PWRGD is internally pulled low when the device is in shutdown
mode, V
DD
is below the internal UVLO threshold, or the device is in thermal shutdown.
D2
FB
Feedback Input. Connect FB to the center tap of an external resistor-divider from the output to GND to set
the output voltage from 0.6V to 90% of V
IN
.
D3
COMP
Voltage-Error Amplifier Output. Connect the necessary compensation network from COMP to FB and the
converter output (see the Compensation Design section). COMP is internally pulled to GND when the
device is in shutdown mode.
D4
REFIN/SS
External Reference Input/Soft-Start Timing Capacitor Connection. Connect REFIN/SS to a system voltage to
force FB to regulate to REFIN/SS voltage. REFIN/SS is internally pulled to GND when the device is in
shutdown and thermal shutdown mode. If no external reference is applied, the internal 0.6V reference is
automatically selected. REFIN/SS is also used to perform soft-start. Connect a minimum of 1nF capacitor
from REFIN/SS to GND to set the startup time (see the Soft-Start and Reference Input (REFIN/SS) section).
CASE TEMPERATURE
vs. AMBIENT TEMPERATURE
MAX15050 toc18
AMBIENT TEMPERATURE (°C)
CASE TEMPERATURE (°C)
60
35
10
-15
-20
0
20
40
60
80
100
-40
-40
85
I
LOAD
= 4A
TRANSITION FROM SKIP MODE
TO FORCED PWM
MAX15050 toc19
I
OUT
2A/div
V
LX
5V/div
V
OUT
500mV/div
10ms/div
TRANSITION FROM FORCED PWM
TO SKIP MODE
MAX15050 toc20
I
OUT
2A/div
V
LX
5V/div
V
OUT
500mV/div
10ms/div