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MAX5083ATE+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18
MAX5082/MAX5083
1.5A, 40V, MAXPower Step-Down
DC-DC Converters
_______________________________________________________________________________________ 7
Detailed Description
The MAX5082/MAX5083 are voltage-mode buck con-
verters with internal 0.3Ω power MOSFET switches. The
MAX5082 has a wide input voltage range of 4.5V to
40V. The MAX5083’s input voltage range is 7.5V to 40V.
The internal low R
DS_ON
switch allows for up to 1.5A of
output current. The 250kHz fixed switching frequency,
external compensation, and voltage feed-forward sim-
plify loop compensation design and allow for a variety
of L and C filter components. Both devices offer an
automatic switchover to pulse-skipping (PFM) mode,
providing low quiescent current and high efficiency at
light loads. Under no load, a PFM mode operation
reduces the current consumption to only 1.4mA. In
shutdown, the supply current falls to 200µA. Additional
features include an externally programmable undervolt-
age lockout through the ON/OFF pin, a programmable
soft-start, cycle-by-cycle current limit, hiccup mode
output short-circuit protection, and thermal shutdown.
PIN
MAX5082
MAX5083
NAME
FUNCTION
11
COMP
Error Amplifier Output. Connect COMP to the compensation feedback network.
22FB
Feedback Regulation Point. Connect to the center tap of a resistive divider from converter
output to SGND to set the output voltage. The FB voltage regulates to the voltage present at SS
(1.23V).
33
ON/OFF
ON/OFF and External UVLO Control. The ON/OFF rising threshold is set to approximately 1.23V.
Connect to the center tap of a resistive divider from IN to SGND to set the UVLO (rising)
threshold. Pull ON/OFF to SGND to shut down the device. ON/OFF can be used for power-
supply sequencing. Connect to IN for always-on operation.
44SS
Soft-Start and Reference Output. Connect a capacitor from SS to SGND to set the soft-start
time. See the Applications Information section to calculate the value of the SS capacitor.
55
SYNC
Oscillator Synchronization Input. SYNC can be driven by an external 150kHz to 350kHz clock to
synchronize the MAX5082/MAX5083’s switching frequency. Connect SYNC to SGND when not
used.
66
DVREG
Gate Drive Supply for High-Side MOSFET Driver. Connect externally to REG for MAX5082.
Connect to REG and the anode of the boost diode for MAX5083.
7 — C+ Charge-Pump Flying Capacitor Positive Connection
8 — C- Charge-Pump Flying Capacitor Negative Connection
— 7, 8 N.C. No Connection. Not internally connected. Can be left floating or connected to SGND.
99
PGND
Power Ground Connection. Connect the input filter capacitor’s negative terminal, the anode of
the freewheeling diode, and the output filter capacitor’s return to PGND. Connect externally to
SGND at a single point near the input capacitor’s return terminal.
10 10 BST
High-Side Gate Driver Supply. Connect BST to the cathode of the boost diode and to the
positive terminal of the boost capacitor.
11, 12 11, 12 LX
Source Connection of Internal High-Side Switch. Connect the inductor and rectifier diode’s
anode to LX.
13, 14 13, 14 IN
Supply Input Connection. Connect to an external voltage source from 4.5V to 40V (MAX5082) or
a 7.5V to 40V (MAX5083).
15 15 REG
Internal Regulator Output. 5V output for the MAX5082 and 8V output for the MAX5083. Bypass
to SGND with at least a 1µF ceramic capacitor.
16 16
SGND
Signal Ground Connection. Solder the exposed pad to a large SGND plane. Connect SGND
and PGND together at one point near the input bypass capacitor return terminal.
EP EP — Exposed Pad. Connect exposed pad to SGND.
Pin Description
MAX5082/MAX5083
1.5A, 40V, MAXPower Step-Down
DC-DC Converters
8 _______________________________________________________________________________________
Internal Linear Regulator (REG)
REG is the output terminal of a 5V (MAX5082), or 8V
(MAX5083) LDO which is powered from IN and pro-
vides power to the IC. Connect REG externally to
DVREG to provide power for the high-side MOSFET
gate driver. Bypass REG to SGND with a ceramic
capacitor of at least 1µF. Place the capacitor physically
close to the MAX5082/MAX5083 to provide good
bypassing. During normal operation, REG is intended
for powering up only the internal circuitry and should
not be used to supply power to external loads.
Internal UVLO/External UVLO
The MAX5082/MAX5083 provides two undervoltage
lockouts (UVLOs). An internal UVLO looks at the input
voltage (V
IN
) and is fixed at 4.1V (MAX5082) or 7.1V
(MAX5083). An external UVLO is sensed and pro-
grammed at the ON/OFF pin. The external UVLO over-
rides the internal UVLO when the external UVLO is
higher than the internal UVLO. During startup, before
any operation begins, the input voltage and the voltage
at ON/OFF must exceed their respective UVLOs. The
external UVLO has a rising threshold of 1.23V with
0.12V of hysteresis. Program the external UVLO by
connecting a resistive divider from IN to ON/OFF to
SGND. Connect ON/OFF to IN directly to disable the
external UVLO.
Driving ON/OFF to ground places the MAX5082/
MAX5083 in shutdown. When in shutdown, the internal
power MOSFET turns off, all internal circuitry shuts
down and the quiescent supply current reduces to
200µA. Connect an RC network from ON/OFF to SGND
to set a turn-on delay that can be used to sequence the
output voltages of multiple devices.
MAX5082
1.23V
1.23V
ON/OFF
DVREG
PCLK
LDO
EN
IN
REG
SS
FB
THERMAL
SHDN
REF
IN
0.3V
CLK
1.23V
REGOK
EN
V
REF
V
REF
I
SS
>1.23V ON
<1.11V OFF
COMP
SYNC
E/A
SSA
CPWM
RAMP
LOGIC
EN
OSC
CHARGE-PUMP
MANAGEMENT
PCLK
BST
IN
SGND
LX
PGND
SCLK
HIGH-SIDE
CURRENT
SENSE
REF_PFM
PFM
REF_ILIM
ILIM
OVERL
CLK
ILIM
OVERLOAD
MANAGEMENT
DVREGC+
DVREG
C-
LEVEL
SHIFT
Figure 1. MAX5082 Simplified Block Diagram
MAX5082/MAX5083
1.5A, 40V, MAXPower Step-Down
DC-DC Converters
_______________________________________________________________________________________ 9
Soft-Start and Reference (SS)
SS is the 1.23V reference bypass connection for the
MAX5082/MAX5083 and also controls the soft-start
period. At startup, after V
IN
is applied and the internal
and external UVLO thresholds are reached, the device
enters soft-start. During soft-start, 15µA is sourced into
the capacitor (C
SS
) connected from SS to SGND caus-
ing the reference voltage to ramp up slowly. When V
SS
reaches 1.23V the output becomes fully active. Set the
soft-start time (t
SS
) using the following equation:
where t
SS
is in seconds and C
SS
is in Farads.
Internal Charge Pump (MAX5082)
The MAX5082 features an internal charge pump to
enhance the turn-on of the internal MOSFET, allowing
for operation with input voltages down to 4.5V. Connect
a flying capacitor (C
F
) between C+ and C-, a boost
diode from C+ to BST, as well as a bootstrap capacitor
(C
BST
) between BST and LX to provide the gate-drive
voltage for the high-side n-channel DMOS switch.
During the on-time, the flying capacitor is charged to
V
DVREG
. During the off-time, the positive terminal of the
flying capacitor (C+) is pumped to two times V
DVREG
and charge is dumped onto C
BST
to provide twice the
regulator voltage across the high-side DMOS driver.
Use a ceramic capacitor of at least 0.1µF for C
BST
and
C
F
located as close to the device as possible.
For applications that do not require a 4.5V minimum
input, use the MAX5083. In this device, the charge
t
VC
A
SS
SS
=
×123
15
.
µ
MAX5083
1.23V
1.23V
ON/OFF
LDO
EN
IN
REG
SS
FB
THERMAL
SHDN
REF
IN
0.3V
CLK
ILIM
1.23V
REGOK
EN
V
REF
V
REF
I
SS
>1.23V ON
<1.11V OFF
COMP
SYNC
E/A
SSA
CPWM
RAMP
LOGIC
EN
OSC
BOOTSTRAP
CONTROL
PCLK
BST
IN
SGND
LX
DVREG
PGND
SCLK
HIGH-SIDE
CURRENT
SENSE
REF_PFM
PFM
REF_ILIM
ILIM
OVERL
CLK
ILIM
OVERLOAD
MANAGEMENT
Figure 2. MAX5083 Simplified Block Diagram
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18

MAX5083ATE+T

Mfr. #:
Buy MAX5083ATE+T
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators 1A 40V MAXPower Step-Down
Lifecycle:
New from this manufacturer.
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