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MAX1638EAG

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
V
MAX1638
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
4 _______________________________________________________________________________________
FREQ = REF
FREQ = V
CC
Falling FB, 1% hysteresis with respect to V
REF
Rising FB, 1% hysteresis with respect to V
REF
FREQ = AGND
Over line and load (Note 1)
V
CC
= V
DD
CONDITIONS
510 600 690
800 1000 1200
Switching Frequency
6810
kHz
240 300 360
%
-8 -6 -4
PWROK Trip Level
%±2.5Output Voltage (FB) Accuracy
V4.5 5.5Input Voltage Range
UNITSMIN TYP MAXPARAMETER
BST - LX = 4.5V
FREQ = V
CC
V
DD
= 4.5V
Ω0.7 2
%84 90
Ω0.7 2
Maximum Duty Cycle
DL On-Resistance
DH On-Resistance
FB = 3.5VCurrent-Limit Trip Voltage mV70 100 130
ELECTRICAL CHARACTERISTICS
(V
DD
= V
CC
= D4 = +5V, PGND = AGND = D0–D3= 0V, FREQ = REF, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 3)
Note 1: FB accuracy is 100% tested at FB = 3.5V (code 10000) with V
CC
= V
DD
= 4.5V to 5.5V and CSH - CSL = 0mV to 80mV. The
other DAC codes are tested with V
CC
= V
DD
= 5V and CSH - CSL = 0.
Note 2: AC load regulation sets the AC loop gain, to make tradeoffs between output filter capacitor size and transient response,
and has only a slight effect on DC accuracy or DC load-regulation error.
Note 3: Specifications from 0°C to -40°C are guaranteed by design, not production tested.
No load V3.448 3.5 3.553Reference Voltage
V
CC
rising edge, 1% hysteresis V3.9 4.3Input Undervoltage Lockout
0.4
Operating mode 3
V
CC
Supply Current
V
CC
= V
DD
= 5.5V, FB forced 200mV above
regulation point, operating or shutdown mode
mA0.2
V
CC
= V
DD
= 5.5V,
FB overdrive =
200mV
V
DD
Supply Current
mA
12
Shutdown
mode
V
REF
= 0V
DAC code = 11111
MAX1638
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
_______________________________________________________________________________________ 5
FOLDBACK CURRENT LIMIT
MAX1638-04
V
O
= 2.0V NOMINAL
A: V
OUT
= 0.5V/div
B: INDUCTOR CURRENT, 5A/div
A
B
10μs/div
STARTUP WAVEFORMS
MAX1638-05
A: V
OUT
= 0.5V/div
B: INDUCTOR CURRENT, 5A/div
A
B
400μs/div
LOAD-TRANSIENT RESPONSE
WITHOUT GLITCHCATCHER (C
OUT
= 880μF)
MAX1638-01
V
IN
= 5V, V
OUT
= 2.0V, LOAD = 14A, 3A/μs
A: V
OUT
, 50mV/div, AC COUPLED
B: INDUCTOR CURRENT, 10A/div
A
B
10μs/div
LOAD-TRANSIENT RESPONSE
WITHOUT GLITCHCATCHER (C
OUT
= 440μF)
MAX1638-02
V
IN
= 5V, V
OUT
= 2.0V, LOAD = 14A, 3A/μs
A: V
OUT
, 100mV/div, AC COUPLED
B: INDUCTOR CURRENT, 10A/div
A
B
10μs/div
LOAD-TRANSIENT RESPONSE
WITH GLITCHCATCHER
MAX1638-03
C
OUT
= 440μF, V
IN
= 5V, V
OUT
= 2.0V, LOAD = 14A, 30A/μs
A: V
OUT
, 100mV/div, C: NDRV, 5V/div
AC COUPLED D: INDUCTOR CURRENT,
B: PDRV, 5V/div 10A/div
A
D
B
C
10μs/div
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, using the MAX1638 evaluation kit, unless otherwise noted.)
100
90
30
0.1 10 100
EFFICIENCY vs. OUTPUT CURRENT
50
40
80
70
60
MAX1638-07
OUTPUT CURRENT (A)
EFFICIENCY (%)
1
V
OUT
= 2.0V
V
OUT
= 1.3V
V
OUT
= 3.5V
5.094
1.094
0.001 0.1 10.01 10
REFERENCE VOLTAGE
vs. OUTPUT CURRENT
1.594
2.094
MAX1638-08
OUTPUT CURRENT (mA)
REFERENCE VOLTAGE (V)
2.594
3.594
3.094
4.094
4.594
SOURCING
CURRENT
SINKING
CURRENT
50
55
0
MAXIMUM DUTY CYCLE
vs. SWITCHING FREQUENCY
65
60
70
MAX1638-09
SWITCHING FREQUENCY (kHz)
MAXIMUM DUTY CYCLE (%)
85
95
90
75
80
200 800 1000 1200
100
600400
MAX1638
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
6 _______________________________________________________________________________________
PIN
High-Side Main MOSFET Switch Gate-Drive Output. DH is a floating driver output that swings from LX
to BST, riding on the LX switching-node voltage. See the section BST High-Side Gate-Driver Supply
and MOSFET Drivers.
DH24
Switching Node. Connect LX to the high-side MOSFET source and inductor.LX23
Power GroundPGND22
DL
Low-Side Synchronous Rectifier Gate-Drive Output. DL swings between PGND and V
DD
. See the
section BST High-Side Gate-Driver Supply and MOSFET Drivers.
21
V
DD
5V Power Input for MOSFET Drivers. Bypass V
DD
to PGND within 0.2 in. (5mm) of the V
DD
pin using a
0.1µF capacitor and 4.7µF capacitor connected in parallel.
20
PDRV GlitchCatcher P-Channel MOSFET Driver Output. PDRV swings between V
DD
and PGND. 19
NDRV GlitchCatcher N-Channel MOSFET Driver Output. NDRV swings between V
DD
and PGND. 18
D4, D3 Digital Inputs for Programming the Output Voltage 16, 17
FREQ
Frequency-Select Input. FREQ = V
CC
: 1MHz
FREQ = REF: 600kHz
FREQ = AGND: 300kHz
15
CC2
Slow-Loop Compensation Capacitor Input. Connect a ceramic capacitor from CC2 to AGND. See the
section Compensating the Feedback Loop.
14
BST
Boost-Capacitor Bypass for High-Side MOSFET Gate Drive. Connect a 0.1µF capacitor and low-leak-
age Schottky diode as a bootstrapped charge-pump circuit to derive a 5V gate drive from V
DD
for DH.
1
NAME FUNCTION
______________________________________________________________Pin Description
CC1
Fast-Loop Compensation Capacitor Input. Connect a ceramic capacitor and resistor in series from
CC1 to AGND. See the section Compensating the Feedback Loop.
13
FB
Voltage-Feedback Input. Connect FB to the CPU’s remote voltage-sense point. The voltage at this input
is regulated to a value determined by D0–D4.
12
PWROK
Open-Drain Logic Output. PWROK is high when the voltage on FB is within +8% and -6% of its set-
point.
2
CSL
Current-Sense Amplifier’s Inverting Input. Place the current-sense resistor very close to the controller IC,
and use a Kelvin connection.
3
CSH Current-Sense Amplifier’s Noninverting Input4
D2, D1,
D0
Digital Inputs for Programming the Output Voltage. D0–D4 are logic inputs that set the output to a volt-
age between 1.3V and 3.5V (Table 2). D0–D4 are internally pulled up to V
CC
with 5µA current sources.
5, 6, 7
LG
Loop Gain-Control Input. LG is a three-level input that is used to trade off loop gain vs. AC load-regula-
tion and load-transient response. Connect LG to V
CC
, REF, or AGND for 2%, 1%, or 0.5% AC load-reg-
ulation errors, respectively.
8
V
CC
Analog Supply Input, 5V. Use an RC filter network, as shown in Figure 1. 9
REF
Reference Output, 3.5V. Bypass REF to AGND with 0.1µF (min). Sources up to 100µA for external
loads. Force REF below 2V to turn off the controller.
10
AGND Analog Ground11
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

MAX1638EAG

Mfr. #:
Buy MAX1638EAG
Manufacturer:
Maxim Integrated
Description:
Switching Controllers High-Speed Step-Down Controller with Synchronous Rectification for CPU Power
Lifecycle:
New from this manufacturer.
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