MAX1960 データシートの表示（PDF） - Maxim Integrated

部品番号

コンポーネント説明

メーカー

MAX1960

2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining

Maxim Integrated 

2.35V to 5.5V, 0.5% Accurate, 1MHz PWM

Step-Down Controllers with Voltage Margining

ILIM

(MAX1960/MAX1961)

OUT

CLKOUT

OSC

FSET/SYNC

OSC

COMP

CURRENT

SENSE

UVLO

LX

PGND

S

COMP

R

Q

VDD

Q

OUT

(MAX1961/MAX1962)

FB

(MAX1960/MAX1962)

VSEL

(MAX1961/MAX1962)

CTL1

(MAX1960/MAX1961)

CTL2

(MAX1960/MAX1961)

EN

(MAX1962)

FEEDBACK

SELECT

SHUTDOWN

AND VOLTAGE

MARGINING

ERROR

AMP

SOFT-START

DAC

MAX1960/

OSC

MAX1961/

MAX1962

REF

CHARGE

PUMP

CS

(MAX1962)

BST

DH

LX

DL

PGND

AVDD

REF

VDD

C+

C-

VCC

GND

Figure 1. Functional Diagram

MOSFET Gate Drivers

The DH and DL drivers are designed to drive logic-level

N-channel MOSFETs to optimize system cost and effi-

ciency. MOSFETs with RDSON rated at VGS 4.5V are

recommended. An adaptive dead-time circuit monitors

the DL output and prevents the high-side MOSFET from

turning on until DL is fully off. There must be a low-resis-

tance, low-inductance path from the DL driver to the

MOSFET gate for the adaptive dead-time circuit to work

properly. Otherwise, the internal sense circuitry could

interpret the MOSFET gate as “off” while there is actually

still charge left on the gate. Use very short, wide traces

measuring no more than 20 squares (50mils to 100mils

wide if the MOSFET is 1in from the IC).

Undervoltage Lockout and Soft-Start

There are two undervoltage lockout (UVLO) circuits on

the MAX1960/MAX1961/MAX1962. The first UVLO cir-

cuit monitors VCC, which must be above 2.15V (typ) in

order for the charge pump to operate. The second

UVLO circuit monitors the output of the charge pump.

The charge-pump output, VDD, must be above 4.2V

(typ) in order for the PWM converter to operate. Both

UVLO circuits inhibit switching and force DL high and DH

low when either VCC or VDD are below their threshold.

When the monitored voltages are above their thresh-

olds, an internal soft-start timer ramps up the error-

amplifier reference voltage. The ramp occurs in eighty

10mV steps. Full output voltage is reached 1.28ms after

activation with a 1MHz operating frequency.

______________________________________________________________________________________ 11

Share Link: