MAX8661ETL+ Maxim Integrated Products, MAX8661ETL+ Datasheet - Page 27

• Manufacturer Part Number: MAX8661ETL+
• Description: IC POWER MANAGE XSCALE 40-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8661ETL+

• Applications: Processor
• Voltage - Supply: 2.6 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 40-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

EN2 is a dedicated enable input for REG2. Drive EN2
high to enable REG2 or drive EN2 low to disable REG2.
EN2 has hysteresis so that an RC may be used to
implement manual sequencing with respect to other
inputs. In systems based on Marvell PXA3xx, EN1,
EN2, and EN5 are typically connected to SYS_EN
(Table 2).
The REG2 step-down regulator operates in either nor-
mal or forced-PWM mode. See the REG1–REG4 Step-
Down DC-DC Converter Operating Modes section for
more information.
The REG2 regulator has an on-chip synchronous rectifier.
See the REG1–REG4 Synchronous Rectification section
for more information.
The REG2 regulator allows 100% duty-cycle operation.
See the REG1/REG2 100% Duty-Cycle Operation
(Dropout) section for more information.
REG3 is a high-efficiency (REG3 + REG8 I
2MHz current-mode step-down converter that has an
I
25mV increments with efficiency up to 92%. The default
REG3 output voltage is 1.4V for the MAX8660/
MAX8660A/MAX8661, and 1.15V for the MAX8660B
(contact factory for other default voltages). REG3 deliv-
ers up to 1.6A. See the I
on how to adjust the output voltage.
REG3 has an I
ware enable pin (EN34). See the REG3/REG4 Enable
(EN34, EN3, EN4) section for more information.
The REG3 step-down regulator operates in either nor-
mal or forced-PWM mode. See the REG1–REG4 Step-
Down DC-DC Converter Operating Modes section for
more information.
The REG3 regulator has an on-chip synchronous rectifier.
See the REG1–REG4 Synchronous Rectification section
for more information.
REG4 is a high-efficiency (REG4 + REG8 I
2MHz current-mode step-down converter that has an
I
25mV increments with efficiency up to 92%. The default
REG4 output voltage is 1.4V for the MAX8660/
MAX8660A/MAX8661, and 1.15V for the MAX8660B
(contact factory for other default voltages). REG4 deliv-
ers up to 400mA. See the I
details on how to adjust the output voltage.
REG4 has an I
ware enable pin (EN34). See the REG3/REG4 Enable
(EN34, EN3, EN4) section for more information.
2
2
C-adjustable output voltage from 0.725V to 1.800V in
C-adjustable output voltage from 0.725V to 1.800V in
REG4 (VCC_SRAM) Step-Down DC-DC Converters
REG3 (VCC_APPS) Step-Down DC-DC Converters
Voltage Management for Mobile Applications
High-Efficiency, Low-I
2
2
C enable bit (EN3) and a shared hard-
C enable bit (EN4) and a shared hard-
______________________________________________________________________________________
2
C Interface section for details
2
C Interface section for
Q
Q
= 45µA)
= 45µA)
The REG4 step-down regulator operates in either nor-
mal or forced-PWM mode. See the REG1–REG4 Step-
Down DC-DC Converter Operating Modes section for
more information.
The REG4 regulator has an on-chip synchronous rectifier.
See the REG1–REG4 Synchronous Rectification section
for more information.
REG1–REG4 independently operate in one of two
modes: normal or forced PWM. At power-up or after a
reset, REG1–REG4 default to normal operation. Activate
forced-PWM mode by setting bits in the FPWM register
(Table 9) with the I
changed at any time.
In forced-PWM mode, a converter operates with a con-
stant 2MHz switching frequency regardless of output
load. The MAX8660/MAX8661 regulate the output volt-
age by modulating the switching duty cycle. Forced-
PWM mode is ideal for low-noise systems because
output voltage ripple is small (< 10mV
ing harmonics occur at multiples of the constant-
switching frequency and are easily filtered. However,
light-load power consumption in forced-PWM mode is
higher than that of normal mode (Table 7).
Normal operation offers improved efficiency at light
loads by switching only as necessary to supply the
load. With moderate to heavy loading, the regulator
switches at a fixed 2MHz switching frequency as it
does in forced-PWM mode. This transition to fixed-fre-
quency switching occurs at the load current specified
in the following equation:
Internal n-channel synchronous rectifiers eliminate the
need for external Schottky diodes and improve efficiency.
The synchronous rectifier turns on during the second
half of each switching cycle (off-time). During this time,
the voltage across the inductor is reversed, and the
inductor current ramps down. In PWM mode, the syn-
chronous rectifier turns off at the end of the switching
cycle. In normal mode, the synchronous rectifier turns
off when the inductor current falls below 25mA or at the
end of the switching cycle, whichever occurs first.
The REG1 and REG2 step-down DC-DC converters
operate with 100% duty cycle when the supply voltage
approaches the output voltage. This allows these
REG1/REG2 100% Duty-Cycle Operation (Dropout)
Q
, PMICs with Dynamic
I
OUT
REG1–REG4 Synchronous Rectification
≅
DC-DC Converter Operating Modes
2
V
C interface. The FPWM bits can be
IN
2
−
x L
V
OUT
REG1–REG4 Step-Down
x
V
IN
V
OUT
x f
P-P
SW
) and switch-
27