MAX1962EEP+ Maxim Integrated Products, MAX1962EEP+ Datasheet - Page 10

• Manufacturer Part Number: MAX1962EEP+
• Description: IC DC-DC CTRL STP DWN 20-QSOP
• Manufacturer: Maxim Integrated Products
• Type: Step-Down (Buck)r

Specifications of MAX1962EEP+

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.8 ~ 4.95 V
• Current - Output: 20A
• Frequency - Switching: 500kHz, 1MHz
• Voltage - Input: 2.35 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-QSOP
• Power - Output: 727mW, 9.1mW
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX1960/MAX1961/MAX1962 are high-current,
high-efficiency voltage-mode step-down DC-DC con-
trollers that operate from 2.35V to 5.5V input and gener-
ate adjustable voltages down to 0.8V at up to 20A. An
on-chip charge pump generates a regulated 5V for dri-
ving a variety of external N-channel MOSFETs.
Constant frequency PWM operation and external syn-
chronization make these controllers suitable for telecom
and datacom applications. The operating frequency is
programmed externally to either 500kHz or 1MHz, or
from 450kHz to 1.2MHz with an external clock. A clock
output is provided to synchronize another converter for
180° out-of-phase operation.
A high closed-loop bandwidth provides excellent tran-
sient response for applications with dynamic loads.
An on-chip regulated charge pump develops 5V at
50mA (max) with input voltages as low as 2.35V. The
output of this charge pump provides power for the
internal circuitry, bias for the low-side driver (DL), and
the bias for the boost diode, which supplies the high-
side MOSFET gate driver (DH). The charge pump is
synchronized with the DL driver signal and operates at
1/2 the PWM frequency.
The external MOSFET gate charge is the dominant load
for the charge pump and is proportional to the PWM
switching frequency. The charge pump must supply
chip-operating current plus adequate gate current for
both MOSFETs at the selected operating frequency.
The required charge-pump output current is given by
the formula:
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM
Step-Down Controllers with Voltage Margining
10
MAX1960 MAX1961 MAX1962
15
16
17
18
19
20
______________________________________________________________________________________
I
TOTAL
PIN
15
16
17
18
19
20
= I
AVDD
Detailed Description
15
16
17
18
19
20
+ f
Internal Charge Pump
OSC
NAME
(Q
V
BST
C+
DH
LX
C-
CC
G1
+ Q
G2
Charge-Pump Flying Capacitor Negative Connection. Use a 0.47µF ceramic
capacitor at 1MHz, and 1µF between 450kHz and 950kHz.
Charge-Pump Flying Capacitor Positive Connection. Use a 0.47µF ceramic
capacitor at 1MHz and 1µF between 450kHz and 950kHz.
Input Supply to Charge Pump
Boost Capacitor Connection. Connect a 0.1µF ceramic capacitor from BST to LX.
High-Side MOSFET Gate-Driver Output. DH is low in shutdown.
Inductor Connection
)
where I
AV
frequency, Q
MOSFET, and Q
MOSFET. The MOSFETs must be chosen such that
I
operation, Q
The voltage-margining feature on the MAX1960/
MAX1961 shifts the output voltage up or down by 4%.
This is useful for the automatic testing of systems at high
and low supply conditions to find potential hardware fail-
ures. CTL1 and CTL2 control voltage margining as out-
lined in Table 1.
A shutdown feature is included on all three parts, which
stops switching the output drivers and the charge
pump, reducing the supply current to less than 15µA.
For the MAX1962, drive EN high for normal operation,
or low for shutdown. For the MAX1960/MAX1961, drive
both CTL1 and CTL2 high for normal operation, or drive
CTL1 and CTL2 low for shutdown. For a simple
enable/shutdown function with no voltage margining,
connect CTL1 and CTL2 together and drive as one
input.
Table 1. Voltage Margining Truth Table
TOTAL
CTL1
DD
High
High
Low
Low
(typically 2mA), f
does not exceed 50mA. For example, with 1MHz
AVDD
G1
Pin Description (continued)
CTL2
Voltage Margining and Shutdown
High
High
Low
Low
FUNCTION
is the current supplied to the IC through
G1
+ Q
G2
is the gate charge of the high-side
G2
is the gate charge of the low-side
Normal operation
+4% output-voltage shift
-4% output-voltage shift
Shutdown
should be less than 48nC.
OSC
is the PWM switching
FUNCTION